GooDrops.java

package referencetypes;

import java.awt.Graphics;
import java.awt.Toolkit
import java.util.Random;

import goo.Goo;

public class GooDrops extends Goo {

	private Drop[] drops;
	private int numDrops, maxSize = 9, maxVel = 9;
	private Random random;
	private GreenDrop greenDrop;

	public GooDrops(int w, int h, int nd) {

		super(w, h);
		numDrops = nd;

		drops = new Drop[numDrops];
		random = new Random(1962); 

		for (int i = 0; i < numDrops; i++) {

			int xpos = random.nextInt(w);
			int ypos = random.nextInt(h);
			int xvel = 1 + random.nextInt(maxVel);
			int yvel = 1 + random.nextInt(maxVel);
			int size = 1 + random.nextInt(maxSize);
			drops[i] = makeDrop(xpos, ypos, xvel, yvel, size);
		}
		greenDrop = new GreenDrop(10,10,10,10,30);
	}
	
	public Drop makeDrop(int xpos, int ypos,int xvel,int yvel, 
			      int size){
		
		return new Drop(xpos, ypos, xvel, yvel, size);
	}

	public void draw(Graphics g) {

		greenDrop.move(getWidth(), getHeight());
		greenDrop.draw(g);
		
		for (int i = 0; i < numDrops; i++) {

			drops[i].move(getWidth(), getHeight());
			drops[i].draw(g);
			
				if(collision(greenDrop, drops[i])){
					Toolkit.getDefaultToolKit().beep();
					System.out.println("happen");
				}
				else{
					System.out.println("not happen");
				}
		}
		
	}
	
	private boolean collision(Drop a, Drop b){
		System.out.println(a.getX());
		System.out.println(b.getX());
		if((a.getX() == b.getX()) && (a.getY() == b.getY())){
			return true;
		}
		else{
			return false;
		}
	}

	public Drop[] getDrops(){
		
		return drops;
	}
	
	public Random getRandom(){
		
		return random;
	}
	
	public static void main(String[] args) {

		int width = 800;
		int height = 500;
		int numDrops = 5;
		GooDrops gd = new GooDrops(width, height, numDrops);
		
		gd.smooth();
		gd.go();
	}
}

GreenDrop.java

package referencetypes;

import java.awt.Color;
import java.awt.Graphics;

public class GreenDrop extends Drop{

	Color color = Color.GREEN;

	public GreenDrop(int x, int y, int vx, int vy, int sz) {
		super(x, y, vx, vy, sz);
	}
	
	public void move(int width,int height){
		xpos = xpos + xvel;
		ypos = ypos + yvel;
		
		if ((ypos) > height || ypos < 0) {
			yvel *= -1;
		}
		
		if((xpos) > width || xpos < 0){
			xvel *= -1;
		}
	}
	
	public void draw(Graphics g){
		
		g.setColor(color);
		g.fillOval(xpos, ypos, size, size);
	}
}