Could Not Find or Load Main Class in Java

It is very common to face errors and exceptions in the Java programming language. But some of the most popular and common errors are often faced by programmers who are new in programming. Among these errors, could not find or load main class in Java, is one of them that occurs usually. The error indicates that the java command failed to find or load the main class. It occurs when we try to run a program. When the error occurs, the JVM shows the following error message on the console:

The error is mostly generated when we incorrectly specify the class name at run time of the program.

Reasons to Occur Error

The error generates because the JVM fails to load the main class or package name. There are some other reasons that generate the same error, as follows:

The class has been declared in the wrong package.
Dependencies missing from the CLASSPATH.
The subdirectory path doesn't match the fully qualified name.
The wrong directory is on the CLASSPATH.
The CLASSPATH of the application is incorrectly specified.
Also occurs, when we have done a mistake with the class name argument.

Solution to the Error

To avoid or resolve the error, we need to specify the absolute package name or class name.

Without Package

The main class is a class in which the main() method is defined. Let's create a program that generates and displays an error on the console.

DemoClass.java

public class DemoClass
{ 
public static void main(String[] args)  
{         
System.out.print("Enter a string: "); 
//using console to input data from user 
String name = System.console().readLine(); 
System.out.println("You have entered: "+name); 
} 
}

Output:

Could Not Find or Load Main Class in Java

We see that the above program compiles and runs, successfully. Let's generate the error that could not find or load main class in the above program. To generate and display the error, we have misspelled the class name while typing the java command java DemoClas.

It also occurs when we specify the .class extension at the end of the class name.

To avoid the error, do not write .class extension at the end of the class name while using the java command.

The error also occurs when we don't place the class in the correct folder. In the following image, we are not inside the demo folder where the class is located. It means the DemoClass.class file must be inside the directory C:\demo.

With Package

In the above program, let's create a package named com.javatpoint. It means, on compiling the following Java program the .class file will be generated inside the C:\demo\com\javatpoint\DemoClass.class.

DemoClass.java

package com.javatpoint;
public class DemoClass
{ 
public static void main(String[] args)  
{         
System.out.print("Enter a string: "); 
//reading a string from the user
String name = System.console().readLine(); 
System.out.println("You have entered: "+name); 
} 
}

Output: