Implementing Your Own Permission

TerrysGame

Below is the source code for TerrysGame. For simplicity, TerrysGame does not actually contain code to play a game. It simply retrieves or updates a user's high score.

To see what the user's current high score value is, you could run:

java TerrysGame get

To set a new high score value for the user, you could run:

java TerrysGame set score 

To retrieve the user's current high score, TerrysGame simply instantiates a HighScore object and makes a call to its getHighScore method. To set a new high score for the user, TerrysGame instantiates a HighScore object and calls setHighScore, passing it the user's new high score.

Here is the source code for TerrysGame, TerrysGame.java:

import java.io.*;
import java.security.*;
import java.util.Hashtable;

public class TerrysGame
{
    public static void main(String args[])
	throws Exception 
    {
	HighScore hs = new HighScore("TerrysGame");

	if (args.length == 0)
	    usage();

	if (args[0].equals("set")) {
	    hs.setHighScore(Integer.parseInt(args[1]));
	} else if (args[0].equals("get")) {
	    System.out.println("score = "+ hs.getHighScore());
	} else {
	    usage();
	}
    }

    public static void usage()
    {
	System.out.println("TerrysGame get");
	System.out.println("TerrysGame set <score>");
	System.exit(1);
    }
}

Implementing Your Own Permission