rand.java

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package myGame.main;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.Date;
import java.util.Random;

/**
 * Global random generator. It must be global so all methods needing random
 * values accesses the same methods. This is because we want similar behaviour
 * on both devices in a remote game, which is achieved by agreeing on a mutual
 * seed.
 * 
 * @author YuBingxing
 */
public class Rand {
	/** The seed */
	protected static long SEED = new Date().getTime();

	/** Native random generator */
	protected static Random RANDOM = new Random(SEED);

	/**
	 * Sets the seed of the random generator.
	 * 
	 * @param seed
	 *            The seed of the random generator.
	 */
	public static void setRandomSeed(long seed) {
		SEED = seed;
		RANDOM = new Random(seed);
	}

	/**
	 * Returns a random integer ranging from Integer.MIN_VALUE to
	 * Integer.MAX_VALUE.
	 * 
	 * @return A random integer value.
	 */
	public static int random() {
		return RANDOM.nextInt();
	}

	/**
	 * Returns a random float ranging from -1.0f to 1.0f.
	 * 
	 * @return A random float value.
	 */
	public static float randomFloat() {
		return 2f * RANDOM.nextFloat() - 1f;
	}

	/**
	 * Loads the seed into random generator.
	 * 
	 * @param dis
	 *            The stream to read from.
	 * @return Number of bytes read.
	 * @throws IOException
	 *             if loading failed
	 */
	public static int loadSeed(DataInputStream dis) throws IOException {
		setRandomSeed(dis.readLong());
		return 8;
	}

	/**
	 * Writes the seed used by random generator.
	 * 
	 * @param dos
	 *            The stream to write to,
	 * @return Number of bytes written.
	 * @throws IOException
	 *             if saving failed
	 */
	public static int saveSeed(DataOutputStream dos) throws IOException {
		dos.writeLong(SEED);
		return 8;
	}

	/** Prevent construction */
	private Rand() {
	}
}