Main.java
import java.applet.*;
import java.awt.*;
import java.awt.Graphics;
import java.awt.Color;
public class Main extends Applet implements Runnable
{
// variables
private Thread th;
private Player player;
private Shot [] shots;
// speed constants
private final int shotSpeed = -2;
private final int playerLeftSpeed = -2;
private final int playerRightSpeed = 2;
// move flags
private boolean playerMoveLeft;
private boolean playerMoveRight;
// double buffering
private Image dbImage;
private Graphics dbg;
public void init()
{
setBackground (Color.black);
player = new Player(150, 280);
shots = new Shot[5];
}
public void start ()
{
th = new Thread(this);
th.start ();
}
public void stop()
{
th.stop();
}
public void destroy()
{
th.stop();
}
public void run ()
{
Thread.currentThread().setPriority(Thread.MIN_PRIORITY);
while (true)
{
// do operations on shots in shots array
for(int i=0; i<shots.length; i++)
{
if(shots[i] != null)
{
// move shot
shots[i].moveShot(shotSpeed);
// test if shot is out
if(shots[i].getYPos() < 0)
{
// remove shot from array
shots[i] = null;
}
// other operations
// ...
// test for collisions with enemies
// ...
}
}
// move player
if(playerMoveLeft)
{
player.moveX(playerLeftSpeed);
}
else if(playerMoveRight)
{
player.moveX(playerRightSpeed);
}
// repaint applet
repaint();
try
{
Thread.sleep(10);
}
catch (InterruptedException ex)
{
// do nothing
}
Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
}
}
public boolean keyDown(Event e, int key)
{
if(key == Event.LEFT)
{
playerMoveLeft = true;
}
else if(key == Event.RIGHT)
{
playerMoveRight = true;
}
else if(key == 32)
{
// generate new shot and add it to shots array
for(int i=0; i<shots.length; i++)
{
if(shots[i] == null)
{
shots[i] = player.generateShot();
break;
}
}
}
return true;
}
public boolean keyUp(Event e, int key)
{
if(key == Event.LEFT)
{
playerMoveLeft = false;
}
else if(key == Event.RIGHT)
{
playerMoveRight = false;
}
return true;
}
public void update (Graphics g)
{
if (dbImage == null)
{
dbImage = createImage (this.getSize().width, this.getSize().height);
dbg = dbImage.getGraphics ();
}
dbg.setColor (getBackground ());
dbg.fillRect (0, 0, this.getSize().width, this.getSize().height);
dbg.setColor (getForeground());
paint (dbg);
g.drawImage (dbImage, 0, 0, this);
}
public void paint (Graphics g)
{
// draw player
player.drawPlayer(g);
// draw shots
for(int i=0; i<shots.length; i++)
{
if(shots[i] != null)
{
shots[i].drawShot(g);
}
}
}
}
Shot.java
import java.applet.*;
import java.awt.*;
import java.awt.Graphics;
import java.awt.Color;
public class Shot
{
private int x_pos;
private int y_pos;
private final int radius = 3;
public Shot ()
{
}
public Shot(int x, int y)
{
x_pos = x;
y_pos = y;
}
public int getYPos()
{
return y_pos;
}
public void moveShot(int speed)
{
y_pos += speed;
}
public void drawShot(Graphics g)
{
g.setColor(Color.yellow);
g.fillOval(x_pos, y_pos, radius, radius);
}
}
Player.java
import java.applet.*;
import java.awt.*;
import java.awt.Graphics;
import java.awt.Color;
public class Player extends Shot
{
// Variables
private int x_pos;
private int y_pos;
public Player(int x, int y)
{
x_pos = x;
y_pos = y;
}
public void moveX(int speed)
{
x_pos += speed;
}
public Shot generateShot()
{
Shot shot = new Shot(x_pos, y_pos);
return shot;
}
public void drawPlayer(Graphics g)
{
g.setColor(Color.red);
int [] x_poly = {x_pos, x_pos - 10, x_pos, x_pos + 10};
int [] y_poly = {y_pos, y_pos + 15, y_pos + 10, y_pos + 15};
g.fillPolygon(x_poly, y_poly, 4);
}
}
