throw keyword in java

Throw:

• It is a keyword.
• It is used to throw an exception object explicitly by the programmer.
• Pre-defined exceptions will be raised(thrown) by JVM automatically.
• Custom exception must be raised manually by the programmer.
• If we don’t handle the exception, object will be submit to “Default Exception Handler” program.

class CustomException extends RuntimeException
{
	CustomException(String name)
	{
		super(name);
	}
}
class ThrowException 
{
	public static void main(String args[])
	{
		CustomException obj = new CustomException("Error-Message");
		throw obj ;
	}
}

• In the above code, custom exception is Runtime Exception
• Compiler will not provide any error in case of not handling Runtime Exceptions.
• Runtime Exception handling is optional but recommended to provide formal messages to end user..

Custom checked Exception:

• Extending from Exception class.
• Handling is mandatory.
• Compiler raises error if we don’t handle exception.

class CustomException extends Exception
{
	CustomException(String name)
	{
		super(name);
	}
}
class ThrowException 
{
	public static void main(String args[])
	{
		CustomException obj = new CustomException("Error-Message");
		throw obj ;
	}
}