Question

I’m developing a J2ME Application and I want to make a good practice for Exception Handling, I’m throwing some exceptions like

ConnectionNotFoundException, IOException, XmlPullParserException, OutOfMemory, Exception

I don’t want to catch all these exception in each method that I make

so I think that I can make a new class

and this class will handle all others

I have made this class

public class ExceptionHandler extends Exception {

    private Exception thrownException;

    public ExceptionHandler(Exception thrownExc) {
        this.thrownException = thrownExc;

        if (thrownException.getClass().isInstance(ConnectionNotFoundException.class)) {
            // DO SOMETHING
        } else if (thrownException.getClass().isInstance(IOException.class)) {
            // DO SOMETHING
        } else if (thrownException.getClass().isInstance(XmlPullParserException.class)) {
            // DO SOMETHING
        } else if (thrownException.getClass().isInstance(NullPointerException.class)) {
            // DO SOMETHING
        } else if (thrownException.getClass().isInstance(OutOfMemoryError.class)) {
            // DO SOMETHING
        } else if (thrownException.getClass().isInstance(Exception.class)) {
            // DO SOMETHING
        }
    }
}

but I don’t know if that is a good way or not and also I have error when I replace the thrown exceptions with mine

so what can I do please ?

Answer 1

You are on the right track, that is the best way to handle errors. You can also pass a second argument called message in your custom exception class and then display message here itself. Something like this:

if (thrownException.getClass().isInstance(ConnectionNotFoundException.class)) {
Dialog.alert(msg);
}

Also from the calling class, you just callnew ExceptionHandler(exception, Constants.msg)

The Constants.java class will hold all the error messages.