I've since just started coding for an android game using eclipse. I've read Beginning Android Game Programming and various other e-books. Recently, I've encountered a problem with collision between sprites. I've used this code template for my program.

package com.project.CAI_test;

import java.util.Random;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Rect;

public class Sprite {
       // direction = 0 up, 1 left, 2 down, 3 right,
       // animation = 3 back, 1 left, 0 front, 2 right
       int[] DIRECTION_TO_ANIMATION_MAP = { 3, 1, 0, 2 };
       private static final int BMP_ROWS = 4;
       private static final int BMP_COLUMNS = 3;
       private static final int MAX_SPEED = 5;
       private GameView gameView;
       private Bitmap bmp;
       private int x = 0;
       private int y = 0;
       private int xSpeed;
       private int ySpeed;
       private int currentFrame = 0;
       private int width;
       private int height;

       public Sprite(GameView gameView, Bitmap bmp) {
             this.width = bmp.getWidth() / BMP_COLUMNS;
             this.height = bmp.getHeight() / BMP_ROWS;
             this.gameView = gameView;
             this.bmp = bmp;

             Random rnd = new Random();
             x = rnd.nextInt(gameView.getWidth() - width);
             y = rnd.nextInt(gameView.getHeight() - height);
             xSpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED;
             ySpeed = rnd.nextInt(MAX_SPEED * 2) - MAX_SPEED;
       }

       private void update() {
             if (x >= gameView.getWidth() - width - xSpeed || x + xSpeed <= 0) {
                    xSpeed = -xSpeed;
             }
             x = x + xSpeed;
             if (y >= gameView.getHeight() - height - ySpeed || y + ySpeed <= 0) {
                    ySpeed = -ySpeed;
             }
             y = y + ySpeed;
             currentFrame = ++currentFrame % BMP_COLUMNS;
       }

       public void onDraw(Canvas canvas) {
             update();
             int srcX = currentFrame * width;
             int srcY = getAnimationRow() * height;
             Rect src = new Rect(srcX, srcY, srcX + width, srcY + height);
             Rect dst = new Rect(x, y, x + width, y + height);
             canvas.drawBitmap(bmp, src, dst, null);
       }

       private int getAnimationRow() {
             double dirDouble = (Math.atan2(xSpeed, ySpeed) / (Math.PI / 2) + 2);
             int direction = (int) Math.round(dirDouble) % BMP_ROWS;
             return DIRECTION_TO_ANIMATION_MAP[direction];
       }

       public boolean isCollition(float x2, float y2) {
             return x2 > x && x2 < x + width && y2 > y && y2 < y + height;
       }
}

The above code only detects collision between the generated sprites and the surface border. What I want to achieve is a collision detection that is controlled by the update function without having to change much of the coding. Probably several lines placed in the update() function. Tnx for any comment/suggestion.