How to Resolve 'IllegalArgumentException' Inaccessibility Error in Java

What causes the 'IllegalArgumentException' is inaccessible from here error in Java and how to fix it?

// Example code snippet that might cause IllegalArgumentException
public void exampleMethod(String input) {
    if(input == null) {
        throw new IllegalArgumentException("Input cannot be null");
    }
}

The 'IllegalArgumentException' is inaccessible from here error occurs in Java when you attempt to utilize this exception without proper imports or context. This can lead to confusion when working with exception handling in your code.

// Correctly throwing IllegalArgumentException
import java.lang.IllegalArgumentException;

public class ArgumentChecker {
    public void checkArgument(String arg) {
        if(arg == null) {
            throw new IllegalArgumentException("Argument cannot be null");
        }
    }
}

Causes

• Lack of proper imports of the java.lang package.
• Attempting to throw or catch the IllegalArgumentException without it being in scope.
• Using the exception in a non-class context, such as within static methods or blocks without import.

Solutions

• Ensure that you have imported the IllegalArgumentException class properly in your Java file with 'import java.lang.IllegalArgumentException;'.
• If you are using a nested class, ensure that IllegalArgumentException is accessible from the scope of that class.
• Make sure the class where you are throwing or catching IllegalArgumentException is properly defined.

Mistake: Forgetting to import the IllegalArgumentException class in your Java file.

Solution: Always include the Java import statement: 'import java.lang.IllegalArgumentException;' at the top of your code.

Mistake: Trying to catch or throw the exception in a wrong context like static blocks without proper class instances.

Solution: Check your context if you're working within static methods, ensuring you reference the exception properly.