---
title: "Java \"NoClassDefFoundError.\" Identify missing class?"  
description: "Java \"NoClassDefFoundError.\" Identify missing class?"  
author: "Steilla Mitchel"  
published: 2023-08-02  
updated: 2023-08-03  
canonical: https://www.mindstick.com/forum/159433/java-noclassdeffounderror-identify-missing-class  
category: "java"  
tags: ["java", "classnotfoundexception"]  
reading_time: 2 minutes  

---

# Java "NoClassDefFoundError." Identify missing class?

[Java](https://www.mindstick.com/articles/12214/web-development-company-in-india-laid-on-the-foundation-of-concrete-java-programming) "NoClassDefFoundError." [Identify missing](https://www.mindstick.com/interview/34512/how-do-you-identify-missing-indexes) [class](https://www.mindstick.com/blog/165/generic-class-in-c-sharp)?

## Replies

### Reply by Aryan Kumar

Sure, I can help you with that.

The `NoClassDefFoundError` error in Java occurs when the Java Virtual Machine (JVM) cannot find a class that is needed at runtime. This can happen for a number of reasons, such as the class not being on the classpath or the class being in a JAR file that is not being included in the classpath.

To [identify](https://www.mindstick.com/forum/159425/java-app-crash-arrayindexoutofboundsexception-identify-invalid-index) the [missing](https://answers.mindstick.com/qa/52138/international-missing-children-s-day-2019-was-observed-on) class, you can use the following steps:

1. **Look at the stack trace.** The stack trace will show you the call stack that led to the `NoClassDefFoundError` error. This will help you to identify the class that is missing.
2. **Check the classpath.** Make sure that the class that is missing is on the classpath. You can use the `java -cp` command to list the classes that are on the classpath.
3. **Check the JAR files.** If the class that is missing is in a JAR file, make sure that the JAR file is included in the classpath. You can use the `jar -tf` command to list the contents of a JAR file.

Once you have identified the missing class, you can either add the class to the classpath or fix the code that is causing the `NoClassDefFoundError` error.

Here are some additional things to keep in mind when identifying missing classes in Java:

- The `NoClassDefFoundError` error can be caused by a number of things, such as a typo in the class name or a missing JAR file.
- The `NoClassDefFoundError` error can be difficult to debug, because the stack trace may not be very helpful.
- If you are still having trouble identifying the missing class, you can ask for help on a forum or from a developer community.


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Original Source: https://www.mindstick.com/forum/159433/java-noclassdeffounderror-identify-missing-class

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