Java Exercise 3 : user defined exception class.

While defining an user defined exception, we need to take care of the following aspects:

• The user defined exception class should extend from Exception class.
• The toString() method should be overridden in the user defined exception class in order to display meaningful information about the exception.

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

public class NegativeMarkException extends Exception {

private int Mark;

public NegativeMarkException(int mark){

this.Mark=mark;

}

    public String toString(){

    return "mark cannot be negative";

    }

}

//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

import java.util.*;

public class UserDefinedException{

public static void main(String[] arg) throws Exception{

int mark = getmark();

try{

if (mark < 0)

throw new NegativeMarkException(mark);

else

System.out.println("mark entered is " + "  "+ mark);

}

finally

{

}

}

static int getmark(){

Scanner input=new Scanner(System.in);

System.out.println("enter the mark");

int m =input.nextInt();

return m;

}

}

///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

Output

enter the mark

 20

mark entered is   20

enter the mark

-20

Exception in thread "main" mark cannot be negative

at UserDefinedException.main(UserDefinedException.java:7)