A Galaga game developed in Java

Alien.java

import java.util.*;

public class Alien extends GameObject
{
	Random dice;
	int cnt = 1;
	int dx;
	int rand = 0;
	boolean shot;
	
	Bullet bullet;
	
	Alien()
	{
		dice = new Random();
		x = dice.nextInt(400);
		y = dice.nextInt(250);
		dx = dice.nextInt(20) + 10;
		attribute = "alien";
		bullet = new Bullet();
		bullet.y = -10;
		shot = false;
		
	}

	public void update()
	{		
		if(cnt%2 != 1)
		{
			x += dx;
			if(x > 500)
				cnt++;
		}
		else
		{
			x -= dx;
			if(x < 0)
				cnt++;
		}	
		
		rand = dice.nextInt(2);
		
		if(alive)
		{
			if(rand == 0 && !shot)
			{
				bullet.x = x + width/2;
				bullet.y = y + 5;
				shot = true;
			}
			
			if(shot)
			{
				bullet.y += 10;
				if(bullet.y >= 500)
				{
					bullet.y = -5;
					shot = false;
				}
			}
		}
		else
		{
			bullet.y = -15;
		}
		
	}
}

Bullet.java

import java.awt.*;
import javax.swing.*;


public class Bullet extends GameObject
{
	Color col;
	Bullet()
	{
		width = 10;
		height = 10;
		
		x = 0;
		y = 0;
		
		attribute = "bullet";
		col = Color.RED;
	}
	
	public void update()
	{
		y -= 10;
	}
	
	public void makeColor()
	{
		col = Color.GREEN;
	}
	public void draw(Graphics g, Component c)
	{
		g.setColor(col);
		g.fillOval(x, y, width, height);
	}
}

CircleAlien.java

public class CircleAlien extends Alien
{

	double t;

	public void update()
	{
		x = 100+ (int) (100 * Math.sin(t));
		y = 100+ (int) (100 *Math.cos(t));
		t += .2;
		
		if(alive)
		{
			if(rand == 0 && !shot)
			{
				bullet.x = x + width/2;
				bullet.y = y + 5;
				shot = true;
			}
			
			if(shot)
			{
				bullet.y += 10;
				if(bullet.y >= 500)
				{
					bullet.y = -5;
					shot = false;
				}
			}
		}
		else
		{
			bullet.y = -15;
		}
	}

}

GalagaPanel.java

import javax.swing.*;
import java.awt.*;
import java.util.*;
import java.awt.event.*;

public class GalagaPanel extends JPanel implements KeyListener
{

	//images
	ImageIcon space, shippic, dumbalien, pred, seekpic;

	//list of all objects in game
	LinkedList<Alien> masterList;

	//ship
	Ship ship;
	Bullet bullet;
	
	int dead, listlength;
	
	GalagaPanel()
	{
		//load images, data, whatever
		space = new ImageIcon("data/space.GIF");
		shippic = new ImageIcon("data/e23.GIF");
		dumbalien = new ImageIcon("data/Alien1.PNG");
		pred = new ImageIcon("data/Alien2.PNG");

		//add some aliens to game
		masterList = new LinkedList<Alien>();
		for(int i=0; i<3; i++)
		{
			Alien a = new Alien();
			a.setPicture(dumbalien);
			masterList.add(a);
		}
		
		CircleAlien ca = new CircleAlien();
		ca.setPicture(dumbalien);
		masterList.add(ca);
				
		//add a ship to the game
		ship = new Ship();
		ship.setPicture(shippic);
		ship.x = 200;
		ship.y = 400;
	
		Predator p1 = new Predator();
		p1.setPicture(pred);
		p1.setPrey(ship);
		masterList.add(p1);
		
		Seeker seek = new Seeker();
		seekpic = new ImageIcon("data/Alien4.PNG");
		seek.setPicture(seekpic);
		seek.setPrey(ship);
		masterList.add(seek);
		
		Predator p2 = new Predator();
		p2.setPicture(pred);
		p2.setPrey(ship);
		masterList.add(p2);
		
		bullet = new Bullet();

		UpdateThread ut = new UpdateThread(this);
		ut.start();
		
		
		//stupid key listener stuff
		addKeyListener(this);
		setFocusable(true);
	}


	public void paintComponent(Graphics g)
	{
		//clear screen
		g.drawImage(space.getImage(),0,0,getWidth(),getHeight(),this);

		//draw all objects in game
		for( Alien go : masterList )
		{
			go.draw(g,this);
			listlength++;
			go.bullet.draw(g, this);
			if(!go.alive)
				dead++;
		}
		ship.draw(g, this);
		bullet.draw(g, this);
		if(ship.alive == false)
		{
			g.setFont(new Font("sansserif", Font.BOLD, 32));
			g.drawString("GAME OVER!!!!", 150, 300);
		}
		if(dead == listlength)
		{
			g.setFont(new Font("sansserif", Font.BOLD, 32));
			g.drawString("GAME WON!!!!", 150, 300);
		}
		else
		{
			listlength = 0;
			dead = 0;
		}
	}


	public void update()
	{
		//update all objects in game
		for( Alien go : masterList )
		{
			go.update();
			if(bullet.intersects(go))
			{
				go.kill();
			}
			
			if(go.intersects(ship) && !go.attribute.equalsIgnoreCase("ship"))
			{
				ship.kill();
				System.out.println(go.attribute + " killed you");
			}
			if(go.bullet.intersects(ship))
			{
				ship.kill();
				System.out.println("Shot by " + go.attribute);
			}
			
		}
		
		//check for bullet shot aliens
		
		bullet.update();
		ship.update();
		
		repaint();
	}

	public void keyPressed(KeyEvent k)
	{
		char c = k.getKeyChar();
		
		if( k.getKeyCode() == KeyEvent.VK_RIGHT )
			ship.dx = 5;
		if( k.getKeyCode() == KeyEvent.VK_LEFT )
			ship.dx = -5;
		if(c == ' ')
		{
			bullet.x = ship.x;
			bullet.y = ship.y - 30;
		}
	}

	public void keyReleased(KeyEvent k)
	{
		if( k.getKeyCode() == KeyEvent.VK_LEFT ||  k.getKeyCode() == KeyEvent.VK_RIGHT )
			ship.dx = 0;
	}

	public void keyTyped(KeyEvent k)
	{
	}

}

GameObject.java

import javax.swing.*;
import java.awt.*;

public class GameObject extends Rectangle
{

	ImageIcon picture;
	boolean alive;
	String attribute = "nothing";
	
	GameObject()
	{
		x= 200;
		y = 200;
		width = 50;
		height = 50;
		alive = true;
	}

	public void setPicture(ImageIcon p)
	{
		picture = p;
	}

	public void draw(Graphics g, Component c)
	{
		if(alive)
		{
			if( picture != null )
				g.drawImage(picture.getImage(),x,y,width,height,c);
			else
			{
				g.setColor(Color.BLUE);
				g.fillRect(x,y,width,height);
			}
		}
	}
	
	public void kill()
	{
			x = 0;
			y = 0;
			width = 0;
			height = 0;
			System.out.println(attribute + " killed");
			alive = false;
		
	}
	public void update()
	{
		x += 1;
		y += 1;
	}
}

main.java

import javax.swing.*;
import java.awt.*;

public class Galaga extends JApplet
{
	public static void main(String [] args)
	{
		//step 1, create a frame
		JFrame frame = new JFrame("Galaga!");

		//step 2, create a panel, put it in frame
		GalagaPanel panel = new GalagaPanel();
		frame.getContentPane().add(panel);

		//step 3, set frame size, make it visible
		frame.setSize(600,600);
		frame.setVisible(true);


	}

}

Predator.java

public class Predator extends Alien
{
	GameObject prey;
	
	//Predator, follows you
	Predator()
	{
		x = dice.nextInt(400);
		y = dice.nextInt(200);
		attribute = "Predator";
	}
	
	public void setPrey(GameObject o)
	{
		prey = o;
	}
	
	public void update()
	{
		if(prey.x < x)
		{
			x -= 5;
		}
		if(prey.x > x)
		{
			x += 5;
		}
		if(prey.y > y)
		{
			y += 3;
		}
		if(prey.y < y)
		{
			y -= 3;
		}
			
		if(alive)
		{
			if(rand == 0 && !shot)
			{
				bullet.x = x + width/2;
				bullet.y = y + 5;
				shot = true;
			}
				
			if(shot)
			{
				bullet.y += 5;
				if(bullet.y >= 500)
				{
					bullet.y = -5;
					shot = false;
				}
			}
		}
		else
		{
			bullet.y = -15;
		}
		
	}

}

Seeker.java

public class Seeker extends Alien
{
	double t;
	GameObject prey;
	
	
	//Seeker, moves around in sine wave, shoots bullets that follow you
	
	Seeker()
	{
		x = dice.nextInt(400);
		y = dice.nextInt(200);
		attribute = "Seeker";
		bullet.makeColor();
	}
	
	public void setPrey(GameObject o)
	{
		prey = o;
	}
	
	public void update()
	{		
		if(cnt%2 != 1)
		{
			x += dx;
			y = 120+ (int) (150 *Math.cos(t));
			t+= .2;
			if(x > 500)
				cnt++;
		}
		else
		{
			x -= dx;
			y = 120+ (int) (150 *Math.cos(t));
			t+= .2;
			if(x < 0)
				cnt++;
		}	
		
		rand = dice.nextInt(2);
		
		if(alive)
		{
			if(rand == 0 && !shot)
			{
				bullet.x = x + width/2;
				bullet.y = y + 5;
				shot = true;
			}
			
			if(shot)
			{
				bullet.y += 5;
				if(prey.x < bullet.x)
				{
					bullet.x -= 4;
				}
				if(prey.x > bullet.x)
				{
					bullet.x += 4;
				}
				if(bullet.y >= 500)
				{
					bullet.y = -5;
					shot = false;
				}
			}
		}
		else
		{
			bullet.y = -15;
		}
		
	}
}

Ship.java

public class Ship extends GameObject
{

	//ship velocity
	int dx;
	
	Ship()
	{
		attribute = "ship";
	}
	public void update()
	{
		x+=dx;
	}

}

UpdateThread.java

import javax.swing.*;

public class UpdateThread extends Thread
{

	GalagaPanel panel;

	UpdateThread(GalagaPanel p)
	{
		panel = p;
	}

	public void run()
	{
		while(true)
		{
			panel.update();

			//wait awhile
			try{Thread.sleep(50);}
			catch(Exception e){}
		}
	}


}