Catching an Exception from a called Method

Question

This is something that\'s been bugging me for a while with regards to Program Flow.

I wanted to know if it\'s possible to catch an error from a Method in order to stop i

Answer 1

If you only want to terminate the whole program in case of an exception you just need to throw a RuntimeException without any further declaration. There are also specialized sub classes for explicit types of exceptions, like NullPointerException or IllegalStateException. See the "Direct Known Subclasses" section in the JavaDoc.

public class MyClass {

    public static void main(String[] args) {
        method01();
        method02(); //method02 won't be called in case of an exception
    }

    private static void method01() {
        // ...
        if (true) // something goes wrong
            throw new RuntimeException();
        // further code won't be executed in case of an exception
    }

    private static void method02() {
        System.out.println("method02 called");
    }
}

Optionally it is possible to handle the exception with a try-catch-block:

    public static void main(String[] args) {
        try {
            method01();
            method02(); // method02 won't be called in case of an exception
        } catch (Exception e) {
            System.err.println("something went wrong");
        }
    }

    // other code keeps unchanged...

If you want to enforce exception handling, you have to throw a subclass of Exception that is not derived from RuntimeException. But those exceptions have to be declared within the method Signature.

    private static void method01() throws IOException {
            throw new IOException();
    }