How to Fix the 'Main Method Not Found' Error in Java Programs

What does the 'Main method not found in class MyClass' error mean in Java, what causes it, and how can it be fixed?

public static void main(String[] args) {
    // Your code here
}

The 'Main method not found' error is a common issue faced by Java programmers, especially those new to the language. It indicates that the Java Virtual Machine (JVM) cannot find the entry point to execute the program, which is the 'main' method. This can result from various code issues, including incorrect method signatures, casing problems, or file structure mistakes.

public class MyClass {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

Causes

• The 'main' method is not defined in the code.
• The 'main' method signature is incorrect (e.g., missing 'static' or 'void').
• The class name does not match the filename if it's being run as an executable.
• The method is not public, causing visibility issues for the JVM.

Solutions

• Ensure that the 'main' method is defined exactly as follows: `public static void main(String[] args)`.
• Check for any typos in the method name or parameters. Make sure to include 'public', 'static', and 'void' in the correct order.
• If using JavaFX, ensure that your class extends `javafx.application.Application` and that you properly override the `start()` method instead of a traditional 'main' method.
• Verify that the filename matches the public class name if the program is compiled as a regular Java application.

Mistake: Defining the main method without 'public'.

Solution: Make sure the method signature is public: `public static void main(String[] args)`.

Mistake: Incorrectly naming the method (e.g., 'Main' instead of 'main').

Solution: Ensure the method is named 'main' with a lowercase 'm'.

Mistake: Omitting the 'static' keyword from the method declaration.

Solution: Always include the keyword 'static' in the main method.

Mistake: Misnaming the class file or class name leading to runtime errors.

Solution: Ensure the class name matches the filename for execution.