No value present java ошибка

In this tutorial, Learn how to fix java.util.NoSuchElementException: No value present error in java application.

This error java.util.NoSuchElementException: No value present thrown when there is no element found in Optional object with Stream API in java8.

Let’s create an array and initialize it with string values. You can check how to create and initialize an array in a single line

Let’s see a simple example to check if a string exists in an array.

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Test {
    public static void main(String[] args) {
        List<String> srs = new ArrayList<>(Arrays.asList("One", "two", "three"));
        String str=srs.stream().filter(e->e.equals("ten")).findFirst().get();


    }
}

It throws an error Exception in thread “main” java.util.NoSuchElementException: No value present

Exception in thread "main" java.util.NoSuchElementException: No value present
    at java.util.Optional.get(Optional.java:135)
    at Test.main(Test.java:8)

Let’s understand the above code.

• Iterated an array using stream API in java8, Stream is another way to iterate the enumerated object to improve performance
• It returns the Stream object using the stream() method
• Calling filter method on stream which matched with a given predicate for each element and returns matched values with stream
• Calling the first element using findFirst from the matched stream and returns Optional class
• if optional Object is empty, get method return no value present error
  i.e Optional.get() method gives java.util.NoSuchElementException when Optional object is empty

Here is a get method implemented in java8

 public T get() {
        if (value == null) {
            throw new NoSuchElementException("No value present");
        }
        return value;
    }

There are multiple ways we can fix to check for the optional object is empty or not.

Let’s see some other simple examples to reproduce and solution for this error

Optional<Integer> number1  =  Optional.of(123);
Optional<Integer> number2  =  Optional.empty();
System.out.println(number1.get()); // 123
System.out.println(number2.get()); // Exception in thread "main" java.util.NoSuchElementException: No value present

One way,

We can check Optional empty or not using isPresent() method in Optional class

        if (number2.isPresent()){
            System.out.println(number2.get());
    }else{
            System.out.println("number2 is an empty");
        }

isPresent()method returns true if value exists, else return false.

Thus, we can avoid an error.

Another way using the orElse method

The orElse method returns the default value assigned with an argument if optional is empty.
otherwise, the returns value is present in the Optional class.

Optional<Integer> number1 = Optional.of(123);
System.out.println(number1.orElse(0)); // 123
Optional<Integer> number2 = Optional.empty();
System.out.println(number2.orElse(0));

Finally, you can use the orElseThrow method.

Sometimes we want to throw an error if Optional is empty, It is handy and helpful.

        Optional<Integer> number1 = Optional.of(123);
        System.out.println(number1.orElse(0)); // 123
        Optional<Integer> number2 = Optional.empty();
        System.out.println(number2.orElseThrow(Exception::new));

We can use either orElse with the default value orElseThrow method.

How to fix NoSuchElement error in java8 streams

Here is a complete example to avoid errors in the java8 stream.

It usually occurs during the streaming process with map, filter etc. methods.

We have to use orElse returns assigned default value else the return value exists in the Optional class.

import java.util.List;
import java.util.Optional;

public class Test {
    public static void main(String[] args)  throws Exception{
        List<String> srs = new ArrayList<>(Arrays.asList("one", "two", "three"));
        String result=srs.stream().filter(e->e.equals("ten")).findFirst().orElse("");
        System.out.println(result);
        String result1=srs.stream().filter(e->e.equals("one")).findFirst().orElse("");
        System.out.println(result1);

    }
}

Conclusion

You learned multiple ways to fix java.util.NoSuchElementException: No value present error in java8 streams.

The java.util.NoSuchElementException: No value present error occurred in spring boot application when an entity object is being attempted to get it from an optional object. If the hibernate returns an empty optional object, this exception Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.util.NoSuchElementException: No value present] will be thrown.The optional object should be validated before accessing the entity object in it. Otherwise, the No value present error will be thrown.

Exception

ERROR 2448 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.util.NoSuchElementException: No value present] with root cause
 java.util.NoSuchElementException: No value present
     at java.base/java.util.Optional.get(Unknown Source) ~[na:na]
     at com.yawintutor.BookController.findOne(BookController.java:42) ~[classes/:na]
     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:na]
     at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:na]
     at java.base/java.lang.reflect.Method.invoke(Unknown Source) ~[na:na]
     at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:893) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:798) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:94) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1589) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [na:na]
     at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [na:na]
     at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at java.base/java.lang.Thread.run(Unknown Source) [na:na]

How to reproduce this issue

From the rest controller, find an entity object that is not available in the database. Spring database repositories returns with optional class without any value. If you tries to access the object, it throws NoSuchElementException.

Root Cause

Access a element in an optional that has no value in it. Optional class throws no such element exception as no element available.

Solution 1

Add proper exception handling code around optional element in rest controller class

@GetMapping("/books/{id}")
Book findOne(@PathVariable Long id) {
    return repository.findById(id).get()
            .orElseThrow(() -> new Exception());
}

Solution 2

Add try catch block to catch and leave this exception

@GetMapping("/books/{id}")
Book findOne(@PathVariable Long id) {
 try {
    return repository.findById(id).get();
 } catch (Exception e) {
    // do nothing or add action code
 }
}

Solution 3

Check the url, path variables and parameters. validate with the database tables and identify why the data is not available in the database.

A quick strip down found out that.
This is the code that cause the error with LexicalPrinter

class InstallPluginCommand extends EnvironmentAwareCommand {

    /** Downloads a zip from the url, into a temp file under the given temp dir. */
    // pkg private for tests
    @SuppressForbidden(reason = "We use getInputStream to download plugins")
    Path downloadZip(Terminal terminal, String urlString, Path tmpDir, boolean isBatch) throws IOException {
        terminal.println(VERBOSE, "Retrieving zip from " + urlString);
        URL url = new URL(urlString);
        Path zip = Files.createTempFile(tmpDir, null, ".zip");
        URLConnection urlConnection = url.openConnection();
        urlConnection.addRequestProperty("User-Agent", "elasticsearch-plugin-installer");
        try (
                InputStream in = isBatch
                        ? urlConnection.getInputStream()
                        : new TerminalProgressInputStream(urlConnection.getInputStream(), urlConnection.getContentLength(), terminal)
        ) {
            // must overwrite since creating the temp file above actually created the file
            Files.copy(in, zip, StandardCopyOption.REPLACE_EXISTING);
        }
        return zip;
    }



}

Remove either one or all of 2 comment lines before @Supress make setup LexicalPrinter successfully

class InstallPluginCommand extends EnvironmentAwareCommand {


    @SuppressForbidden(reason = "We use getInputStream to download plugins")
    Path downloadZip(Terminal terminal, String urlString, Path tmpDir, boolean isBatch) throws IOException {
        terminal.println(VERBOSE, "Retrieving zip from " + urlString);
        URL url = new URL(urlString);
        Path zip = Files.createTempFile(tmpDir, null, ".zip");
        URLConnection urlConnection = url.openConnection();
        urlConnection.addRequestProperty("User-Agent", "elasticsearch-plugin-installer");
        try (
                InputStream in = isBatch
                        ? urlConnection.getInputStream()
                        : new TerminalProgressInputStream(urlConnection.getInputStream(), urlConnection.getContentLength(), terminal)
        ) {
            // must overwrite since creating the temp file above actually created the file
            Files.copy(in, zip, StandardCopyOption.REPLACE_EXISTING);
        }
        return zip;
    }



}

In this tutorial, Learn how to fix java.util.NoSuchElementException: No value present error in java application.

This error java.util.NoSuchElementException: No value present thrown when there is no element found in Optional object with Stream API in java8.

Let’s create an array and initialize it with string values. You can check how to create and initialize an array in a single line

Let’s see a simple example to check if a string exists in an array.

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class Test {
    public static void main(String[] args) {
        List<String> srs = new ArrayList<>(Arrays.asList("One", "two", "three"));
        String str=srs.stream().filter(e->e.equals("ten")).findFirst().get();


    }
}

It throws an error Exception in thread “main” java.util.NoSuchElementException: No value present

Exception in thread "main" java.util.NoSuchElementException: No value present
    at java.util.Optional.get(Optional.java:135)
    at Test.main(Test.java:8)

Let’s understand the above code.

• Iterated an array using stream API in java8, Stream is another way to iterate the enumerated object to improve performance
• It returns the Stream object using the stream() method
• Calling filter method on stream which matched with a given predicate for each element and returns matched values with stream
• Calling the first element using findFirst from the matched stream and returns Optional class
• if optional Object is empty, get method return no value present error
  i.e Optional.get() method gives java.util.NoSuchElementException when Optional object is empty

Here is a get method implemented in java8

 public T get() {
        if (value == null) {
            throw new NoSuchElementException("No value present");
        }
        return value;
    }

There are multiple ways we can fix to check for the optional object is empty or not.

Let’s see some other simple examples to reproduce and solution for this error

Optional<Integer> number1  =  Optional.of(123);
Optional<Integer> number2  =  Optional.empty();
System.out.println(number1.get()); // 123
System.out.println(number2.get()); // Exception in thread "main" java.util.NoSuchElementException: No value present

One way,

We can check Optional empty or not using isPresent() method in Optional class

        if (number2.isPresent()){
            System.out.println(number2.get());
    }else{
            System.out.println("number2 is an empty");
        }

isPresent()method returns true if value exists, else return false.

Thus, we can avoid an error.

Another way using the orElse method

The orElse method returns the default value assigned with an argument if optional is empty.
otherwise, the returns value is present in the Optional class.

Optional<Integer> number1 = Optional.of(123);
System.out.println(number1.orElse(0)); // 123
Optional<Integer> number2 = Optional.empty();
System.out.println(number2.orElse(0));

Finally, you can use the orElseThrow method.

Sometimes we want to throw an error if Optional is empty, It is handy and helpful.

        Optional<Integer> number1 = Optional.of(123);
        System.out.println(number1.orElse(0)); // 123
        Optional<Integer> number2 = Optional.empty();
        System.out.println(number2.orElseThrow(Exception::new));

We can use either orElse with the default value orElseThrow method.

How to fix NoSuchElement error in java8 streams

Here is a complete example to avoid errors in the java8 stream.

It usually occurs during the streaming process with map, filter etc. methods.

We have to use orElse returns assigned default value else the return value exists in the Optional class.

import java.util.List;
import java.util.Optional;

public class Test {
    public static void main(String[] args)  throws Exception{
        List<String> srs = new ArrayList<>(Arrays.asList("one", "two", "three"));
        String result=srs.stream().filter(e->e.equals("ten")).findFirst().orElse("");
        System.out.println(result);
        String result1=srs.stream().filter(e->e.equals("one")).findFirst().orElse("");
        System.out.println(result1);

    }
}

Conclusion

You learned multiple ways to fix java.util.NoSuchElementException: No value present error in java8 streams.

The java.util.NoSuchElementException: No value present error occurred in spring boot application when an entity object is being attempted to get it from an optional object. If the hibernate returns an empty optional object, this exception Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.util.NoSuchElementException: No value present] will be thrown.The optional object should be validated before accessing the entity object in it. Otherwise, the No value present error will be thrown.

Exception

ERROR 2448 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is java.util.NoSuchElementException: No value present] with root cause
 java.util.NoSuchElementException: No value present
     at java.base/java.util.Optional.get(Unknown Source) ~[na:na]
     at com.yawintutor.BookController.findOne(BookController.java:42) ~[classes/:na]
     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
     at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:na]
     at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:na]
     at java.base/java.lang.reflect.Method.invoke(Unknown Source) ~[na:na]
     at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:893) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:798) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:898) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:634) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883) ~[spring-webmvc-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at javax.servlet.http.HttpServlet.service(HttpServlet.java:741) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53) ~[tomcat-embed-websocket-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:94) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119) ~[spring-web-5.1.10.RELEASE.jar:5.1.10.RELEASE]
     at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202) ~[tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:526) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:860) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1589) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source) [na:na]
     at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source) [na:na]
     at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) [tomcat-embed-core-9.0.26.jar:9.0.26]
     at java.base/java.lang.Thread.run(Unknown Source) [na:na]

How to reproduce this issue

From the rest controller, find an entity object that is not available in the database. Spring database repositories returns with optional class without any value. If you tries to access the object, it throws NoSuchElementException.

Root Cause

Access a element in an optional that has no value in it. Optional class throws no such element exception as no element available.

Solution 1

Add proper exception handling code around optional element in rest controller class

@GetMapping("/books/{id}")
Book findOne(@PathVariable Long id) {
    return repository.findById(id).get()
            .orElseThrow(() -> new Exception());
}

Solution 2

Add try catch block to catch and leave this exception

@GetMapping("/books/{id}")
Book findOne(@PathVariable Long id) {
 try {
    return repository.findById(id).get();
 } catch (Exception e) {
    // do nothing or add action code
 }
}

Solution 3

Check the url, path variables and parameters. validate with the database tables and identify why the data is not available in the database.

How to Fix java.util.NoSuchElementException in Java?

An unexpected, unwanted event that disturbed the normal flow of a program is called Exception. Most of the time exceptions are caused by our program and these are recoverable. Suppose if our program requirement is to read data from the remote file locating in the U.S.A. At runtime, if a remote file is not available then we will get RuntimeException saying fileNotFoundException. If fileNotFoundException occurs we can provide the local file to the program to read and continue the rest of the program normally.

There are mainly two types of exception in java as follows:

1. Checked Exception: The exception which is checked by the compiler for the smooth execution of the program at runtime is called a checked exception. In our program, if there is a chance of rising checked exceptions then compulsory we should handle that checked exception (either by try-catch or throws keyword) otherwise we will get the compile-time error. Examples of checked exceptions are ClassNotFoundException, IOException, SQLException, etc.

2. Unchecked Exception: The exceptions which are not checked by the compiler, whether programmer handling or not such type of exception are called an unchecked exception. Examples of unchecked Exceptions are ArithmeticException, ArrayStoreException, etc.

Whether the exception is checked or unchecked every exception occurs at run time only if there is no chance of occurring any exception at compile time.

NoSuchElementException:

It is the child class of RuntimeException and hence it is an unchecked exception. This exception is rise automatically by JVM and given by the accessors methods of Enumeration, Iterator or Tokenizer such as next() or nextElement() or nextToken() when we are trying to access the content of an array, collection, or any other object and if these objects are empty or if we are trying to get next element after reaching the end of an object then we will get java.util.NoSuchElementException.

In the below example we are trying to access a HashMap by using the accessor method next() of the Iterator class but as the HashMap is empty we will be going to get NoSuchElementException.

Источник

Fix the NoSuchElementException Error in Java

An exception is an event that happens during a program’s execution. The normal program flow is affected when an exception occurs, and the program terminates abnormally. This tutorial will discuss java.util.NoSuchElementException and how to handle it in Java.

The NoSuchElementException inherits from the RuntimeException class, which means it’s an unchecked Exception. Unchecked Exceptions are not handled by the compiler, as they happen during runtime.

The NoSuchElementException is thrown by Scanner class, Iterator interface, Enumerator interface, and StringTokenizer class. These classes have accessors’ methods to fetch the next element from an iterable. They throw NoSuchElementException if the iterable is empty or has reached the maximum limit.

Let’s look at how different classes throw NoSuchElementException .

NoSuchElementException While Using Iterator in Java

The Iterator interface has a method called next() used to access the next element in the iteration. If no element is in the collection, then NoSuchElementException is thrown. We will look at some examples.

Trying to iterate a HashMap with no elements:

The next() method throws an exception because the HashMap is empty. We can use the hasNext() method to avoid this exception; it returns true if the iterable has more elements.

We should use the next() method only if hasNext() returns True, to avoid such exceptions. See the example below.

This code throws no exception. Let’s take an example with some elements in the HashMap and iterate the elements.

Without the hasNext() method, this code would have thrown an exception, but it’s working fine.

NoSuchElementException While Using Enumeration in Java

In Java, Enumeration has a method called nextElement() that returns the next element of the enumeration. If there’s no element to return, it throws a NoSuchElementException .

Look at the example below where we are creating an enum from a list.

The hasElement() throws an exception after returning the first element because no elements are left in the ArrayList to be accessed. We can use the hasMoreElements() method to avoid this situation.

This method returns true if there are more elements in the enumeration to provide; else, it returns false. We can call the nextElement() method only if there are more elements in the enumeration.

Look at the example below:

NoSuchElementException While Using StringTokenizer in Java

In Java, StringTokenizer class provides two methods, the nextToken() and nextElement() . The nextToken() method returns the next token(string type) from the string tokenizer, whereas the nextElement method is like the nexttoken() except that it returns an object type rather than a string. Both methods throw the NoSuchElementException .

See the example below.

We can avoid the exception using the hasMoreTokens() and hasMoreElements() method. Both methods return true if more tokens are available in the tokenizer’s string. We should call the nextToken() method only if hasMoreTokens() method returns True.

See the example below:

NoSuchElementException While Using Scanner Class in Java

The Scanner class in Java provides several utility methods such as next(), nextInt(), etc. While working with these methods, they can throw the NoSuchElementException . We will discuss them here.

1. Suppose you have two scanner objects accessing the Standard Input. If you close one of them and call a method using the other one, it throws the NoSuchElementException . See the example below.

When we close the first Scanner, it closes the underlying InputStream ; therefore, the second Scanner can’t read from the same InputStream and throws a NoSuchElementException . The solution is to use one scanner object to read System.in input.

1. Suppose you’re reading a string or a file using the scanner object. If there’s no line left to read, an exception shows. See the example below.

To solve this problem, we use the hasNextLine() method that returns a Boolean value. Look at the example.

Источник

How to Fix the No Such Element Exception in Java

Table of Contents

The NoSuchElementException is an unchecked exception in Java that can be thrown by various accessor methods to indicate that the element being requested does not exist.

Since the NoSuchElementException is thrown at runtime, it does not need to be declared in the throws clause of a method or constructor.

What Causes NoSuchElementException

The NoSuchElementException can be thrown by various classes or interfaces in Java such as Iterator , Enumerator , Scanner or StringTokenizer .

If an element is requested using the accessor methods of these classes or interfaces, and the underlying data structure does not contain the element, the NoSuchElementException is thrown.

This can occur if the data structure is empty or if its next element is requested after reaching the end of the structure.

NoSuchElementException Example

Here is an example of a NoSuchElementException thrown when trying to access an element of an empty ArrayList using an accessor method of the Iterator interface:

In the above example, an element of the ArrayList list is requested using the Iterator.next() accessor method. However, since list is empty, the element requested does not exist and the operation throws a NoSuchElementException:

How to Fix NoSuchElementException

To fix the NoSuchElementException , it should be ensured that the underlying object contains more elements before using accessor methods that can throw the exception. The classes or interfaces that contain these accessor methods usually have a corresponding method to check whether the object contains more elements or not.

For example, the Iterator interface contains the hasNext() method, which should be called before calling Iterator.next() to ensure that the underlying object contains more elements. The Iterator.next() method should only be called if Iterator.hasNext() returns true .

In the earlier example, the exception can be resolved by implementing the above:

Running the above code produces the correct output as expected:

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Источник

Multiple ways to fix java.util.NoSuchElementException: No value present error in java

In this tutorial, Learn how to fix java.util.NoSuchElementException: No value present error in java application.

This error java.util.NoSuchElementException: No value present thrown when there is no element found in Optional object with Stream API in java8.

Let’s create an array and initialize it with string values. You can check how to create and initialize an array in a single line

Let’s see a simple example to check if a string exists in an array.

It throws an error Exception in thread “main” java.util.NoSuchElementException: No value present

Let’s understand the above code.

• Iterated an array using stream API in java8, Stream is another way to iterate the enumerated object to improve performance
• It returns the Stream object using the stream() method
• Calling filter method on stream which matched with a given predicate for each element and returns matched values with stream
• Calling the first element using findFirst from the matched stream and returns Optional class
• if optional Object is empty, get method return no value present error i.e Optional.get() method gives java.util.NoSuchElementException when Optional object is empty

Here is a get method implemented in java8

There are multiple ways we can fix to check for the optional object is empty or not.

Let’s see some other simple examples to reproduce and solution for this error

We can check Optional empty or not using isPresent() method in Optional class

isPresent() method returns true if value exists, else return false .

Thus, we can avoid an error.

Another way using the orElse method

The orElse method returns the default value assigned with an argument if optional is empty. otherwise, the returns value is present in the Optional class.

Finally, you can use the orElseThrow method.

Sometimes we want to throw an error if Optional is empty, It is handy and helpful.

We can use either orElse with the default value orElseThrow method.

How to fix NoSuchElement error in java8 streams

Here is a complete example to avoid errors in the java8 stream.

It usually occurs during the streaming process with map , filter etc. methods.

We have to use orElse returns assigned default value else the return value exists in the Optional class.

Источник

What is the cause of NoSuchElementException

The NoSuchElementException in Java is thrown when one tries to access an iterable beyond its maximum limit. This means that, this exception is thrown by various accessor methods to indicate that the element being requested does not exist . The next() method in Java returns the next element in the iteration or NoSuchElementException if the iteration has no more elements.

example

output

How to solve NoSuchElementException?

As with most programming languages, the Iterator class includes a hasNext() method that returns a boolean indicating if the iteration has anymore elements. If hasNext() returns true, then the next() method will return the next element in the iteration otherwise raise exceptions if the iteration has no more elements. The solution to this? exception is to check whether the next position of an iterable is filled or empty . The following methods are used to check the next position:

example

This way ensures that any element is being accessed if it exists.

java.util.NoSuchElementException

An exception is a problem that arises during the execution of a program. An exception can occur for many different reasons. The NoSuchElementException is an unchecked exception and thus, it does not need to be declared in a method’s or a constructor’s throws clause. The full exception hierarchy of this error is:

The java.util.NoSuchElementException is a RuntimeException which can be thrown by different classes in Java like Iterator, Enumerator, Scanner or StringTokenizer . It is thrown by the following methods:

1. nextElement() of Enumeration interface
2. next() of NamingEnumeration interface
3. nextElement() of StringTokenizer class
4. next() of Iterator interface

Similarly, the previous() method of the ListIterator returns the previous element of the collection, if this method is invoked on an empty object or at the stating position of it a NoSuchElementException is generated at the runtime.

Источник

A quick strip down found out that.
This is the code that cause the error with LexicalPrinter

class InstallPluginCommand extends EnvironmentAwareCommand {

    /** Downloads a zip from the url, into a temp file under the given temp dir. */
    // pkg private for tests
    @SuppressForbidden(reason = "We use getInputStream to download plugins")
    Path downloadZip(Terminal terminal, String urlString, Path tmpDir, boolean isBatch) throws IOException {
        terminal.println(VERBOSE, "Retrieving zip from " + urlString);
        URL url = new URL(urlString);
        Path zip = Files.createTempFile(tmpDir, null, ".zip");
        URLConnection urlConnection = url.openConnection();
        urlConnection.addRequestProperty("User-Agent", "elasticsearch-plugin-installer");
        try (
                InputStream in = isBatch
                        ? urlConnection.getInputStream()
                        : new TerminalProgressInputStream(urlConnection.getInputStream(), urlConnection.getContentLength(), terminal)
        ) {
            // must overwrite since creating the temp file above actually created the file
            Files.copy(in, zip, StandardCopyOption.REPLACE_EXISTING);
        }
        return zip;
    }



}

Remove either one or all of 2 comment lines before @Supress make setup LexicalPrinter successfully

class InstallPluginCommand extends EnvironmentAwareCommand {


    @SuppressForbidden(reason = "We use getInputStream to download plugins")
    Path downloadZip(Terminal terminal, String urlString, Path tmpDir, boolean isBatch) throws IOException {
        terminal.println(VERBOSE, "Retrieving zip from " + urlString);
        URL url = new URL(urlString);
        Path zip = Files.createTempFile(tmpDir, null, ".zip");
        URLConnection urlConnection = url.openConnection();
        urlConnection.addRequestProperty("User-Agent", "elasticsearch-plugin-installer");
        try (
                InputStream in = isBatch
                        ? urlConnection.getInputStream()
                        : new TerminalProgressInputStream(urlConnection.getInputStream(), urlConnection.getContentLength(), terminal)
        ) {
            // must overwrite since creating the temp file above actually created the file
            Files.copy(in, zip, StandardCopyOption.REPLACE_EXISTING);
        }
        return zip;
    }



}

In this post, we’ll provide 4+ fixes for the ‘Exception in thread “main” java.util.NoSuchElementException’ error.

Java programming is a widely known programming language that serves a general purpose in application development. Java is easily the most popular coding language and is running on more or less 3 billion devices worldwide.

However, Java users also encounter errors whilst in the process of programming. One of which is the Exception in thread “main” java.util.NoSuchElementException. This will occur if the exception is thrown to indicate that there are no more elements in an enumeration.

In simpler terms, exceptions are considered abnormal conditions in Java programming. These are events that disrupt the normal flow of a program. You can see a bunch of people experiencing this error over on Twitter:

Exception in thread «main» java.util.NoSuchElementException: No line found
at java.util.Scanner.nextLine(Unknown Source)
at aya.SecondFilePreproc.main(https://t.co/24bmqe3V4W)

— ␀ (@typenullbot) January 26, 2019

#Geeting Exception in thread «main» java.util.NoSuchElementException while retrieving the element from HashMap#Te… https://t.co/bFba7LW8gO

— Micheal Hartwig (@eblogit) March 29, 2016

What is it?

This exception message will appear as a result of various coding errors. The most common cause of this error is when it is in the context of a Scanner when programmers call nextLine(), and there’s no next line that follows.

Also, this exception error can also stem from the following ways:

• Enumeration::nextElement()
• NamingEnumeration::next()
• StringTokenizer::nextElement() – a string tokenizer class allows an application to break and divide a string into multiple tokens
• Iterator::next() – An iterator allows the programmer to remove elements from an underlying collection. The exception error is shown when the iterator is empty. For example, when the following method of an Iterator instance is called when hasNext of that instance returns false.

Quick Video Fix

In the video below, the tech vlogger says that you will find this kind of exception while automating a web application. He covers the reasons for this exception and how you can resolve it.

Programmers initially expect the machine to initially output “Text Input:”. After which it allows the user to input more text which will result in becoming output afterward. If you encounter the “Exception in thread “main” java.util.NoSuchElementException” message while in the middle of typing your codes or after scanning, you can follow these easy steps listed below.

1st Fix

As was mentioned before, this exception error message usually results from a multitude of causes. Therefore, the first fix to be discussed will be the most common and general fix.

Based on oracle.com, it is imperative that you should use a Scanner when trying to fix these kinds of errors. Listed below are important steps in ensuring you have not avoided these.

1. While using Scanner, the user must check if there is a next line with hasNextLine().
2. Also, keep in mind that it is dependent on whether the input is properly formatted.

A Scanner class also issues this same exception if it encounters special characters it cannot read. Also, ensure that the correct encoding is passed to the Scanner constructor.

2nd Fix

Here is another fix to a common error source. According to Javacodegeeks, this is a very common and average error case. This case usually occurs when a Java application tends to iterate over an empty Set. In order to prevent this error from happening, a Java application should call the hasNext first.

An example from their website is shown below:

3rd Fix:

The NoSuchElementException lengthens the period of the RuntimeException class and hence belongs to the exceptions which can be thrown during the Java Virtual Machine (JVM) operation. A RuntimeException class is considered the superclass of these exceptions that can be commonly thrown when under the normal operation process of the JVM. It’s an unchecked exception, and it doesn’t need to be proclaimed in a constructor’s or a method’s throws clause.

In order to indicate that no more elements are present, all the aforementioned methods try to revert to the next element of an enumeration and throw that exception.

Whenever a Java application tries to iterate over an empty Set is considered a very common error. In order for the programmer to avoid this error, the following steps are listed below:

1. A Java application should have the hasNext
2. If hasNext is not available, try to have a hasMoreElements or StringTokenizer methods

4th fix (Preventive)

This fourth fix is a preventive measure rather than an actual solution. This helps in avoiding the exception to be thrown into the code. Follow the two steps listed below:

1. If a programmer is not sure about the number of ints in his or her file, do not try to store them into a fixed-size array. Try to utilize ArrayList instead.
2. Do not use endless loop while(true) but consider using Input.hasNext() to examine if there still is something to read from a file.

Forum Feedback

To understand more about this common Java error, we search through several Java support forums.

In general, users were asking about Exception in thread “main” java.util.NoSuchElementException no value present, Exception in thread “main” java.util.NoSuchElementException scanner, and Exception in thread “main” java.util.NoSuchElementException next on empty iterator.

They also wanted to know about Exception in thread “main” java.util.NoSuchElementException none.get.

A forum user shared that he was a novice to Java programming and that he was trying to write a code to execute a program converting inches to centimeters.

• However, he kept getting an error saying, “Exception in thread “main” java.util.NoSuchElementException.”
• He looked over his code, but he couldn’t find his mistake, so he asked other Java programmers to help him.
• The community was very helpful, and they explained that Exception in thread “main” java.util.NoSuchElementException appears when you attempt to read something from the “Scanner,” but there is nothing to be read. So, you get an error because the element you’re looking for doesn’t exist.

#Encountering «Exception in thread «main» java.util.NoSuchElementException» error for assignment#Tech #HowTohttps://t.co/SiHwXgTqt9

— Micheal Hartwig (@eblogit) January 25, 2016

A couple of Java programmer recommend that if you want to learn how to fix NoSuchElementException errors, you must learn to read your stack and find the line of code where the exception is thrown. Then it’s easy to work from there and fix the problem.

Another forum member explained that if you get the Exception in thread “main” java.util.NoSuchElementException error, you should read more about exception-handling mechanisms in Java. He adds that you have to check that you’ve implemented your “Scanner” method correctly or if you have programmed “new Scanner” twice. The user also advises that you spell check to make sure that you’ve not mistyped anything in the code.

An individual advised that you check if you have any elements in the “Scanner” when you get NoSuchElementException. He adds that “Scanner” is a class and as such, it has a method. Namely: hasNext() which you should use to test if there is anything more to be read. For example, you can use the following code to check:

if(scan.hasNextInt()){
person = scan.nextInt();
} else {
//show error
return;
}

Another user also complained that he kept getting NoSuchElementException even though he has checked his elements. Other Java users took a look at this code and recommended that he close some of his System.in statements because they were throwing the exception. They also said that he should add a catch to prevent crashes.

A person suggests that Exception in thread “main” java.util.NoSuchElementException might appear if you’re reading and writing one file without saving it first. He also adds that you might want to use RandomAccessFile which is accessed directly and as such, doesn’t need other files to be read first.

What does this error mean? – Java Forums: Exception in thread «main» java.util.NoSuchElementException at java.ut… http://bit.ly/e6DHEJ

— Jon (@compgurru) January 25, 2011

Another forum poster explains that you’ll get the NoSuchElementException error if the file your program is supposed to read is empty or what’s inside it doesn’t match the parameters you’ve inputted in the code. For example, if you’ve programmed the code to read 40 values from a file of 10, you’ll get an error after the 10th because there is nothing else to read. That’s why the Java expert points out that you have to employ “hasNext()” method to check if you have a Next item.

A Java programmer comments that it’s not a good practice to have too many “Scanners” in your code and that it’s better to instantiate “Scanner” once and then use it again if there is a need for it. He also remarks that you shouldn’t close those Scanner objects which point to System in. You might forget to open it again and that will create an error such as Exception in thread “main” java.util.NoSuchElementException.

#Exception in thread «main» java.util.NoSuchElementException – not sure what’s going wrong#HowTo #Question #Techhttps://t.co/PFr7QDPGrP

— Micheal Hartwig (@HartwigMicheal) January 6, 2016

Another person also said that he had problems with the NoSuchElementException. When he posted his code on a Java forum, he understood that one line of his code was calling nextInt() but since there was no next input available, he got the error. A fellow member that he had to read more about Scanner’s class methods and employ one of them to check for available input before calling nextInt(). The user also recommended that he read the API doc for more information.

A novice programmer was baffled when he got the error Exception in thread “main” java.util.NoSuchElementException: No line found. However, the problem was a very simple one – he had forgotten one square bracket in the main method and that what throwing the exception. Other users also pointed out that you’ll get NoSuchElementException: No line found if you’re calling “sc.nextLine()” when you don’t have more lines that could be called.

Summing Up

Various programmer errors that are usually overlooked can contribute to the exception being thrown in the code. As such, a multitude of solutions is also needed in order to fix these errors.

The most common cause of the exception is when it looks like you are trying to call next even if the scanner no longer has a next element to provide. When you trying to fix this exception error message, try to check if a scanner has next item to read. You can use hasNext(), hasNextInt().

Also, a more detailed discussion on Scanner exception errors and whatnot can be found through this Reddit link.

An unexpected, unwanted event that disturbed the normal flow of a program is called Exception. Most of the time exceptions are caused by our program and these are recoverable. Suppose if our program requirement is to read data from the remote file locating in the U.S.A. At runtime, if a remote file is not available then we will get RuntimeException saying fileNotFoundException. If fileNotFoundException occurs we can provide the local file to the program to read and continue the rest of the program normally.

There are mainly two types of exception in java as follows:

1. Checked Exception: The exception which is checked by the compiler for the smooth execution of the program at runtime is called a checked exception. In our program, if there is a chance of rising checked exceptions then compulsory we should handle that checked exception (either by try-catch or throws keyword) otherwise we will get the compile-time error. Examples of checked exceptions are ClassNotFoundException, IOException, SQLException, etc.

2. Unchecked Exception: The exceptions which are not checked by the compiler, whether programmer handling or not such type of exception are called an unchecked exception. Examples of unchecked Exceptions are ArithmeticException, ArrayStoreException, etc.

Whether the exception is checked or unchecked every exception occurs at run time only if there is no chance of occurring any exception at compile time.

NoSuchElementException:

It is the child class of RuntimeException and hence it is an unchecked exception. This exception is rise automatically by JVM and given by the accessors methods of Enumeration, Iterator or Tokenizer such as next() or nextElement() or nextToken() when we are trying to access the content of an array, collection, or any other object and if these objects are empty or if we are trying to get next element after reaching the end of an object then we will get java.util.NoSuchElementException.

In the below example we are trying to access a HashMap by using the accessor method next() of the Iterator class but as the HashMap is empty we will be going to get NoSuchElementException.

Example 1:

Example 2: Here we are trying to access the element of an empty vector object through an enumerator.

How to solve this error?

Almost all the classes whose accessor methods give NoSuchElementException contains their respective method to check whether the object contains more elements or not. So in order to avoid this NoSuchElementException we need to always call,

• Iterator.hasNext() or
• Enumeration.hasMoreElements() or
• hasMoreToken() method before calling next( ) or nextElement or nextToken() method.

Below is the implementation of the above statement :

Example 1:

Output:

 Example 2:

Output: