I've always found processing command line parameters in Java something of
a hassle. It's not hard, but it can be error prone and
having to write the same code over and over is annoying.

Here's a class I wrote that I find useful for this. Usage:

String usage = "java " + YourClass.class.getName() + " -a FirstParam -b
SecondParam";
CmdLineProcessor cmdLine = new CmdLineProcessor(args, usage);
cmdLine.setExpectedArgumentCount(4);
if (cmdLine.process()) {
	String firstParam = cmdLine.getArgument("-a");
	String secondParam = cmdLine.getArgument("-b");
	System.out.println("Parameters were " + firstParam + " and " +
secondParam);
}
// usage message is output if process() did not return true

The class:

public class CmdLineProcessor {
	private String[] args;
	private int expectedArgumentCount = 0;
	private String usageMessage;

	public CmdLineProcessor(String[] args, String usage) {
		this.args = args;
		setUsageMessage(usage);
	}

	public boolean process() {
		if ((args == null)
			|| (args.length != expectedArgumentCount)) {

			System.err.println(getUsageMessage());
			return false;
		}
		return true;
	}

	public String getArgument(String param)
			throws IllegalArgumentException {
		for (int i = 0; i < args.length; i++) {
			if (param.equals(args[i] )) {
				if (args.length > (i + 1)) {
					return args[i+1];
				}
			}
		}
		System.err.println(getUsageMessage());
		throw new IllegalArgumentException();
	}

	public int getExpectedArgumentCount() {
		return expectedArgumentCount;
	}

	public String getUsageMessage() {
		return usageMessage;
	}

	public void setExpectedArgumentCount(int i) {
		expectedArgumentCount = i;
	}

	public void setUsageMessage(String string) {
		usageMessage = string;
	}
}

Feel free to reuse it as you need.