Java Throws Keyword

In a java programming, throws keyword list the type of exception that a method might throw.

In the throws clause, we declare all the exception that a method can throw.

Syntax:

type  method_name(parameter list) throws exception1, exception2 ….{		
}

1 2	type method_name(parameter list) throws exception1, exception2 ….{ }

Here, exception1, exception2 are comma, list of the exception that a method can throw.

Example:

class ExceptionClass {
    void demo() throws NullPointerException { // define throws
        System.out.println("Inside demo method.");
        throw new NullPointerException("demo");
    }
}
public class ExceptionMain {
    public static void main(String args[]) {
        ExceptionClass ob = new ExceptionClass();
        try {
            ob.demo(); // demo() definition comes within try block
        } catch (NullPointerException e) {
            System.out.println("Caught " + e);
        }
    }
}

class ExceptionClass {

void demo() throws NullPointerException { // define throws

System.out.println("Inside demo method.");

throw new NullPointerException("demo");

}

public class ExceptionMain {

public static void main(String args[]) {

ExceptionClass ob = new ExceptionClass();

try {

ob.demo(); // demo() definition comes within try block

} catch (NullPointerException e) {

System.out.println("Caught " + e);

}

Inside demo method.
Caught java.lang.NullPointerException: demo

1 2	Inside demo method. Caught java.lang.NullPointerException: demo

Explaination: We throws NullPointerException in the line “throw new NullPointerException(“demo”);” .

Here we set “demo” is a name of thread.

This line “throw new NullPointerException(“demo”);” throw the exception which is handled by catch block associated with try within main().