java: find program name, parse integer argument

Question

A simple test case to demonstrate my 2 problems:

public class Numbers {

    private static void usage() {
        System.err.println("Usage: java " + getClass().getName() + " range");
        System.exit(1);
    }

    public static void main(String[] args) throws IOException {
        try {
            int range = Integer.parseInt(args[0]);
        } catch (Exception e) {
            usage();
        }
    }
}

1. Can't call getClass() from a static method
2. If no arguments have been supplied at the command line, I'll get ArrayIndexOutOfBoundsException message instead of the usage() output. Why doesn't catch (Exception e) catch it?

Answer 1

1) getClass is a method on the Object type. In static methods there is no object to call the getClass on

2) The exception is caught in your example - I just tested it.

Answer 2

Works for me, exception is caught.

Getting the class name from a static method without referencing the Numbers.class.getName() is difficult.

But I found this

String className = Thread.currentThread().getStackTrace()[2].getClassName(); 
System.err.println("Usage: java " + className + " range");