Как выловить java util nosuchelementexception
Перейти к содержимому

Как выловить java util nosuchelementexception

  • автор:

Как выловить java util nosuchelementexception

Constructs a NoSuchElementException , saving a reference to the error message string s for later retrieval by the getMessage method.

Method Summary

Methods inherited from class java.lang.Throwable

Methods inherited from class java.lang.Object

Constructor Detail

NoSuchElementException
public NoSuchElementException()

Constructs a NoSuchElementException with null as its error message string.

NoSuchElementException

Constructs a NoSuchElementException , saving a reference to the error message string s for later retrieval by the getMessage method.

Java™ Platform
Standard Ed. 8

Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2024, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.

java.util.NoSuchElementException при обработке ввода с консоли

из вашей ошибки понятно что ругается на то что вы не ввели необходимое количество строк в консоли.

думаю стоит немного обновить ваш код:

String s = input.readLine(); s = s.replaceAll ("[-_;]", "" ) ); if (s.equalsIgnoreCase ( a1 + b1 + c1 )) < arrStud[i] = "ACC"; >else
 arrStud[i] = (s.equalsIgnoreCase ( a1 + b1 + c1 ) ? "ACC" : "WA"); 

Отслеживать
ответ дан 19 мая 2011 в 19:11
6,252 16 16 серебряных знаков 21 21 бронзовый знак

Совершенно непонятно, что за странную вещь делает этот код.

java.util.NoSuchElementException: No line found 

Совершенно очевидно, что это потому, что количество введённых строк не соответствует числу, которое было в четвёртой строке. Если всё аккуратно вписать, то программа работает.

Ну, если уж на то пошло, то стоит использовать StringBuilder в функции del, а ваша версия ужасающе неэффективна.

Кроме того, ваша программа упадёт в случае, если стандартный ввод будет закрыт раньше времени (раньше, чем будут переданы n строк).

И, тем не менее, было бы лучше, если бы вы лучше конкретизировали свой вопрос.

Saved searches

Use saved searches to filter your results more quickly

Cancel Create saved search

You signed in with another tab or window. Reload to refresh your session. You signed out in another tab or window. Reload to refresh your session. You switched accounts on another tab or window. Reload to refresh your session.

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

java.util.NoSuchElementException #2523

LiWeiQiangAndroid opened this issue May 26, 2023 · 2 comments

java.util.NoSuchElementException #2523

LiWeiQiangAndroid opened this issue May 26, 2023 · 2 comments

Comments

LiWeiQiangAndroid commented May 26, 2023 •
edited by pyricau

Description

java.util.NoSuchElementException: Sequence contains no element matching the predicate. at leakcanary.internal.activity.screen.LeakScreen.onLeakTraceSelected(LeakScreen.kt:273) at leakcanary.internal.activity.screen.LeakScreen.onLeaksRetrieved(LeakScreen.kt:104) at leakcanary.internal.activity.screen.LeakScreen.access$onLeaksRetrieved(LeakScreen.kt:36) at leakcanary.internal.activity.screen.LeakScreen$createView$$inlined$apply$lambda$1$1.invoke(LeakScreen.kt:61) at leakcanary.internal.activity.screen.LeakScreen$createView$$inlined$apply$lambda$1$1.invoke(LeakScreen.kt:36) at leakcanary.internal.activity.db.Io$execute$2$1.invoke(Io.kt:50) at leakcanary.internal.activity.db.Io$execute$2$1.run(Io.kt:10) at android.os.Handler.handleCallback(Handler.java:938) at android.os.Handler.dispatchMessage(Handler.java:99) at android.os.Looper.loopOnce(Looper.java:226) at android.os.Looper.loop(Looper.java:313) at android.app.ActivityThread.main(ActivityThread.java:8751) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:571) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1135) 

The text was updated successfully, but these errors were encountered:

How to Fix the No Such Element Exception in Java

How to Fix the No Such Element Exception in Java

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:

public class NoSuchElementExceptionExample < public static void main(String args[]) < Listlist = new ArrayList(); Iterator it = list.iterator(); System.out.println(it.next()); > >

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:

Exception in thread "main" java.util.NoSuchElementException at java.base/java.util.ArrayList$Itr.next(ArrayList.java:970) at NoSuchElementExceptionExample.main(NoSuchElementExceptionExample.java:9)

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:

public class NoSuchElementExceptionExample < public static void main(String args[]) < Listlist = new ArrayList(); Iterator it = list.iterator(); while (it.hasNext()) < System.out.println(it.next()); > System.out.println("Continuing execution. "); > >

Running the above code produces the correct output as expected:

Continuing execution. 

Track, Analyze and Manage Errors With Rollbar

Managing errors and exceptions in your code is challenging. It can make deploying production code an unnerving experience. Being able to track, analyze, and manage errors in real-time can help you to proceed with more confidence. Rollbar automates error monitoring and triaging, making fixing Java errors easier than ever. Sign Up Today!

Related Resources

Can Constructors Throw Exceptions in Java
Handling the ClassCastException Runtime Exception in Java

«Rollbar allows us to go from alerting to impact analysis and resolution in a matter of minutes. Without it we would be flying blind.»

Добавить комментарий

Ваш адрес email не будет опубликован. Обязательные поля помечены *