FAQ: Could Not Find Or Load Main Class?

When you get the message “Could not find or load main class “, that means that the first step has failed. The java command was not able to find the class. And indeed, the “” in the message will be the fully qualified class name that java is looking for.

How do you fix could not find or load main class?

Could Not Find or Load Main Class in Java

  1. Reasons to Occur Error. The error generates because the JVM fails to load the main class or package name.
  2. Solution to the Error. To avoid or resolve the error, we need to specify the absolute package name or class name.
  3. Without Package.
  4. With Package.

How do I fix resolve could not find or load main class error in eclipse?

Solution of Error: Could not find or load main class in Eclipse

  1. Delete existing run configurations. When you run the main class as “Run as Java Program”, it adds the default classpath of the project as User entries into Run Configurations’s classpath as shown below.
  2. Check for missing library.
  3. Debug the Java program.
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Could not find or load main class java application?

There are many ways Error: Could not find or load main class HelloWorld manifests itself, but if you know the basics of Java Classpath, you can easily sort out the problem. Most of the time you just need to either correct your CLASSPATH environment variable or run your program with java -cp or -classpath option.

Could not find main class program will exit?

There are two ways to do it: Reinstall the new JRE. It should then fix the file association in the OS. Fix the file association manually.

Why do we need classpath in Java?

The CLASSPATH defines the path, to find third-party and user-defined classes that are not extensions or part of Java platform. class files and JAR files when setting the CLASSPATH. You need to set the CLASSPATH if: You need to load a class that is not present in the current directory or any sub-directories.

How do you set classpath?


  1. Select Start.
  2. Go to the Control Panel.
  3. Select System and Security.
  4. Select Advanced System settings.
  5. Click on Environment Variables.
  6. Click on New under System Variables.
  7. Add CLASSPATH as variable name and path of files as a variable value.
  8. Select OK.

How do I clean my Eclipse project?

Configure Eclipse to clean and build only selected projects:

  1. Click Project > Clean.
  2. Uncheck Clean projects selected below.
  3. Ensure Start a build immediately is checked and click Build only the selected projects.
  4. Select the projects that you want to rebuild.

How do I find the main class in Eclipse?

From the Eclipse IDE menu, select Search>Java…. In the dialog, enter: “main” as the search string.

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How do I fix class not found exception in eclipse?

How to Resolve ClassNotFoundException in Java

  1. Find out which JAR file contains the problematic Java class.
  2. Check whether this JAR is present in the application classpath.
  3. If that JAR is already present in the classpath, make sure the classpath is not overridden (e.g. by a start-up script).

How do I run a.jar file?

Double-click the JAR file. If it’s executable and you have Java installed, it should open. If it doesn’t open, proceed to the next step. You may see a pop-up window asking which program you want to use to open the file. If so, click Java(TM) and then click OK.

How do I fix Exception in thread main Java Lang NoClassDefFoundError?

How to resolve java. lang. NoClassDefFoundError in Java

  1. The class is not available in Java Classpath.
  2. You might be running your program using the jar command and class was not defined in the manifest file’s ClassPath attribute.
  3. Any start-up script is an overriding Classpath environment variable.

Could not find the main class program will exit in eclipse?

Right click on your project name in the project explorer, select properties, choose Java compiler, select the JRE version (like 1.6) that you installed on your system in the Compiler compliance level, then click OK and run the program! Done!

How do I fix the Java Virtual Machine launcher?

How to Fix Java Virtual Machine Launcher Error

  1. Use the built-in Windows utility. Image Credit: Siri Stafford/Digital Vision/Getty Images.
  2. Click “Start,” and type “msconfig” Image Credit: Pixland/Pixland/Getty Images.
  3. Click the “Startup” tab.
  4. Remove the check mark next to “WJView.exe” and “javaw.exe.”
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How do you run a Java program?

How to run a java program

  1. Open a command prompt window and go to the directory where you saved the java program (MyFirstJavaProgram. java).
  2. Type ‘javac MyFirstJavaProgram.
  3. Now, type ‘ java MyFirstJavaProgram ‘ to run your program.
  4. You will be able to see the result printed on the window.

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