how to use throw in java code example

Example 1: java how to throw exception

public class ThrowException{
  public static void main(String [] args) throws Exception{ 
    //throws Exception line is needed if not using try-catch block
    throw new Exception("Errmessage");
  }
}

Example 2: java throw an exception

public static void main(String[] args) {
	Scanner kb = new Scanner(System.in);
    System.out.println("Enter a number");
    try {
    	double nb1 = kb.nextDouble();
    	if(nb1<0)
        	throw new ArithmeticException();
        else System.out.println( "result : " + Math.sqrt(nb1) );
    } catch (ArithmeticException e) {
        System.out.println("You tried an impossible sqrt");
    }
}

Example 3: throw keyword in java

Generally JVM throws the exception and
we handle the exceptions by 
using try catch block. But there are
situations where we have to throw 
userdefined exceptions or runtime exceptions.
  In such case we use throw keyword 
to throw exception explicitly.

  Syntax : throw throwableInstance;

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Python Example

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