Develop Reference

How to call a function and have it continue by pressing a key once?

I want the ball.move(); function in the code below to continue running after pressing space once. It only works if I continue pressing the space key.
void draw() {
if (start == true) {ball.move();}
}
void keyPressed() {
if (key == ' '){start = true;}
}
void keyReleased() {
if (key == ' ') {start = false;}
}
It's for a Pong game I am making and each time the ball hits the edge it is teleported to the center of the canvas. That´s when I want to be able to start the ball movement manually again.
Here is the whole code:
Ball ball;
Player player1;
Player player2;
int scorePlayer1 = 0;
int scorePlayer2 = 0;
PFont font;
boolean start;
void setup() {
size(1368,768);
frameRate(144);
noStroke();
ball = new Ball(width/2, height/2, 30);
player1 = new Player(15, height/2, 30, 150);
player2 = new Player(width-15, height/2, 30, 150);
ball.speedX = 10;
}
void draw() {
background(0);
textSize(40);
textAlign(CENTER);
font = loadFont("Arial-Black-48.vlw");
textFont(font);
ball.display();
if (start == true) {ball.move();}
player1.run();
player2.run();
//Score
if (ball.left() < 0) {
scorePlayer2 = scorePlayer2 + 1;
ball.x = width/2;
ball.y = height/2;
}
if (ball.right() > width) {
scorePlayer1 = scorePlayer1 +1;
ball.x = width/2;
ball.y = height/2;
}
text(scorePlayer1, width/2-75, 50);
text(scorePlayer2, width/2+75, 50);
//Collision
if (ball.top() < 0) {
ball.speedY = -ball.speedY;
}
if (ball.bottom() > height) {
ball.speedY = -ball.speedY;
}
if (ball.left() < player1.right() && ball.y > player1.top()-10 && ball.y < player1.bottom()+10) {
ball.speedX = -ball.speedX;
ball.speedY = map(ball.y - player1.y, -player1.h/2, player1.h/2, -5, 5);
}
if (ball.right() > player2.left() && ball.y > player2.top()-10 && ball.y < player2.bottom()+10) {
ball.speedX = -ball.speedX;
ball.speedY = map(ball.y - player2.y, -player2.h/2, player2.h/2, -5, 5);
}
if (player1.bottom() > height) {
player1.y = height-player1.h/2;
}
if (player1.top() < 0) {
player1.y = player1.h/2;
}
if (player2.bottom() > height) {
player2.y = height-player1.h/2;
}
if (player2.top() < 0) {
player2.y = player1.h/2;
}
}
//Movement
void keyPressed() {
player1.pressed((key == 'w' || key == 'W'), (key == 's' || key == 'S'));
player2.pressed((keyCode == UP), (keyCode == DOWN));
if (key == ' '){start = true;}
}
void keyReleased() {
player1.released((key == 'w' || key == 'W'), (key == 's' || key == 'S'));
player2.released((keyCode == UP), (keyCode == DOWN));
if (key == ' ') {start = false;}
}
class Ball {
float x;
float y;
float d;
float speedX;
float speedY;
color c;
//Constructor
Ball(float tempX, float tempY, float tempD){
x = tempX;
y = tempY;
d = tempD;
speedX = 0;
speedY = 0;
c = (255);
}
void display() {
fill(c);
ellipse(x,y,d,d);
}
void move() {
x = x + speedX;
y = y + speedY;
}
//Collision help
float top() {
return y-d/2;
}
float bottom() {
return y+d/2;
}
float left() {
return x-d/2;
}
float right() {
return x+d/2;
}
}
class Player {
float x, y;
float w, h;
float speedY = 0.0;
color c;
boolean moveUp = false, moveDown = false;
//Constructor
Player(float tempX, float tempY, float tempW, float tempH){
x = tempX;
y = tempY;
w = tempW;
h = tempH;
speedY = 0;
c = (255);
}
void run() {
display();
move();
}
void display() {
fill(c);
rect(x-w/2, y-h/2, w, h);
}
//Movement
void move() {
if (!moveUp && !moveDown) {speedY = speedY * 0.85;}
if (moveUp) {speedY -= 1;}
if (moveDown) {speedY += 1;}
speedY = max(-7.0, min(7.0, speedY));
y += speedY;
}
void pressed(boolean up, boolean down) {
if (up) {moveUp = true;}
if (down) {moveDown = true;}
}
void released(boolean up, boolean down) {
if (up) {moveUp = false;}
if (down) {moveDown = false;}
}
//Collision help
float top() {
return y-h/2;
}
float bottom() {
return y+h/2;
}
float left() {
return x-w/2;
}
float right() {
return x+w/2;
}
}

In the code below, you are setting start to true when the key is pressed and false when the press is done. You can simply remove the line that sets start to false when the key press is done and the ball will always move when the space is pressed.
//Movement
void keyPressed() {
player1.pressed((key == 'w' || key == 'W'), (key == 's' || key == 'S'));
player2.pressed((keyCode == UP), (keyCode == DOWN));
if (key == ' '){start = true;}
}
void keyReleased() {
player1.released((key == 'w' || key == 'W'), (key == 's' || key == 'S'));
player2.released((keyCode == UP), (keyCode == DOWN));
//if (key == ' ') {start = false;}
}
I suppose you want the ball to stop moving when space is pressed again. This can be done in your keyPressed method as well by toggling start instead of setting it to true. Something like if (key == ' '){start = !start;}

Your problem is that when you release the space bar, it sets the start field to false. Then when the next draw() method is called, it sees that start==false and so doesn't move the ball.
If you remove that line from the keyReleased method, then it should run correctly?

My code that makes me jump in my platformer also breaks my collision code

So I'm just making a 2d game in my spare time and I am having a hard time understanding why my collision code breaks after my character jumps but works when my character is jumping.
Relevant Code from the main class
public void collision() {
Rectangle body = jan.getBody();
int bodyX = (int) body.getX();
int bodyY = (int) body.getY();
if (bodyX < 0) {
body.setLocation(0, bodyY);
jan.setBody(body);
}
if (bodyX > 780) {
body.setLocation(780, bodyY);
jan.setBody(body);
}
if (bodyY > 360) {
body.setLocation(bodyX, 360);
jan.setBody(body);
}
}
public void actionPerformed(ActionEvent e) {
jan.update();
collision();
repaint();
}
public void keyPressed(KeyEvent e) {
int keyCode = e.getKeyCode();
if (keyCode == KeyEvent.VK_LEFT) {
jan.setDirection(-1);
} else if (keyCode == KeyEvent.VK_RIGHT) {
jan.setDirection(1);
} else if (keyCode == KeyEvent.VK_SPACE) {
jan.jump();
}
}
Relevant code from the Player Class
public void jump() {
int y = (int) body.getY();
if (y == 360) {
body.translate(0, -15);
yVelocity = 15;
}
}
public void update() {
int x = getDirection();
if (x == 1) {
if (xVelocity < terminalVelocity) {
xVelocity++;
}
}
if (x == -1) {
if (xVelocity > -terminalVelocity) {
xVelocity--;
}
}
if (x == 0) {
if (xVelocity < 0) {
xVelocity++;
} else if (xVelocity > 0) {
xVelocity--;
}
}
if (body.y < 360) {
yVelocity--;
}
body.translate(xVelocity, -yVelocity);
}
Any reasons for why my code breaks down after my character jumps?

The logic of collision undoes the clamping in X if Y is also out of bounds. Try clamping in both x and y and then update the body if there's a change:
public void collision() {
Rectangle body = jan.getBody();
int bodyX = (int) body.getX();
int bodyY = (int) body.getY();
int clampedBodyX = Math.min(Math.max(0, bodyX), 780);
int clampedBodyY = Math.min(Math.max(0, bodyY), 360);
if (bodyX != clampedBodyX || bodyY != clampedBodyY) {
body.setLocation(clampedBodyX, clampedBodyY);
jan.setBody(body);
}
}

Why collision algorithm in my applet game does not work properly ?

This is my game project. It's very simple version of "Flappy Bird" and I have some serious problems with how the collisions algorithm works. I wrote 2 separate code fragments for collision, for wall1 and wall2. The problem begins when the ball is trying to go through a hole because somehow the program is detecting a collision with a wall. I'm almost positive that the collision algorithm was written correctly because I have been checking it all day.
import java.applet.*;
import java.awt.*;
import java.awt.event.*;
import java.util.Random;
import java.util.Timer;
import java.util.logging.Level;
import java.util.logging.Logger;
public class Game extends Applet implements KeyListener, Runnable {
Image bground;
Random generator = new Random();
int r1;
int wall1x;
int wall1y;
int wall1long;
int wall2x;
int wall2y;
int wall2long;
Timer timer;
private Image i;
private Graphics doubleG;
int r2;
int blok_x1 = 800;
int blok_y1;
int blok_x = 800;
int blok_y = 0;
int blok_x_v = 2;
int ballX = 20;
int ballY = 20;
int dx = 0;
int dyclimb = 1;
int dyrise = 1;
double gravity = 3;
double jumptime = 0;
int FPS = 100;
public int tab[];
public boolean grounded = true, up = false;
boolean OVER = false;
#Override
public void init() {
bground = getImage(getCodeBase(), "12.png");
this.setSize(600, 400);
tab = new int[100];
for (int t = 0; t < 100; t++) {
tab[t] = generator.nextInt(380) + 1;
}
addKeyListener(this);
}
#Override
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
ballX -= 10;
}
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
ballX += 10;
}
if (e.getKeyCode() == KeyEvent.VK_UP) {
ballY -= 10;
up = true;
}
if (e.getKeyCode() == KeyEvent.VK_DOWN) {
ballY += 10;
}
}
#Override
public void paint(Graphics g) {
g.drawImage(bground, 0, 0, this);
if (OVER == false) {
for (int i = 0; i < 100; i++) {
g.setColor(Color.green);
wall1x = blok_x + i * 400;
wall1y = blok_y;
wall1long = tab[i];
g.fillRect(wall1x, wall1y, 20, wall1long);
g.setColor(Color.green);
wall2x = blok_x1 + i * 400;
wall2y = tab[i] + 60;
wall2long = 400 - tab[i];
g.fillRect(wall2x, wall2y, 20, wall2long);
g.setColor(Color.green);
}
g.setColor(Color.red);
g.fillOval(ballX, ballY, 20, 20);
} else {
g.drawString("GAME OVER", 300, 300);
}
}
#Override
public void update(Graphics g) {
if (i == null) {
g.setColor(Color.green);
i = createImage(this.getSize().width, this.getSize().height);
doubleG = i.getGraphics();
g.setColor(Color.green);
}
doubleG.setColor(getBackground());
g.setColor(Color.green);
doubleG.fillRect(0, 0, this.getSize().width, this.getSize().height);
doubleG.setColor(getForeground());
g.setColor(Color.green);
paint(doubleG);
g.drawImage(i, 0, 0, this);
}
#Override
public void run() {
int time = 10;
while (true) {
if (up == true) {
ballY -= dyclimb;
time--;
} else {
ballY += dyrise;
}
if (time == 0) {
time = 10;
up = false;
}
blok_x--;
blok_x1--;
if (ballX > 600 || ballX < 0 || ballY > 400 || ballY < 0) {
OVER = true;
}
for (int i = 0; i < 100; i++) { // collision algorithm
wall1x = blok_x + i * 400;
wall1y = blok_y;
wall1long = tab[i];
if (ballX + 20 >= wall1x && ballX <= wall1x + 20 && ballY <= wall1y + wall1long && ballY >= wall1x - 20) { //wall1
OVER = true;
}
}
for (int i = 0; i < 100; i++) {
wall2x = blok_x1 + i * 400;
wall2y = tab[i] + 60;
wall2long = 400 - tab[i];
if (ballX + 20 >= wall2x && ballX <= wall2x + 20 && ballY <= wall2y + wall2long && ballY >= wall2x - 20) { //wall2
OVER = true;
}
}
repaint();
try {
Thread.sleep(17);
} catch (InterruptedException ex) {
Logger.getLogger(NewApplet.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
#Override
public void start() {
Thread thread = new Thread(this);
thread.start();
}
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
}
}

Use Rectangle class. There's a method called Intersect or Intersection or something like that.
Say you have one object moving. Make a Rectangle to match the object in position(basically an invisible cover for the object).
Do the same things with another object.
When both are to collide, use the intersection method to check on the collision by using the rectangles.
These might help
http://docs.oracle.com/javase/7/docs/api/java/awt/Rectangle.html
Java method to find the rectangle that is the intersection of two rectangles using only left bottom point, width and height?
java.awt.Rectangle. intersection()

2d array of objects

im really new in Java. I just need to explain how to declare 2D array of objects, i have something like:
package breakout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.Color;
import java.awt.Font;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JOptionPane;
public class Breakout extends JPanel {
public class Ball {
private
int x = 400;
int y = 300;
int speed = 2;
int dirx = 1;
int diry = -1;
public
void bounce(int px, int py, int lx, int ly) {
if ((x + 10 >= 800 && dirx == 1) || (x <= 0 && dirx == -1))
dirx *= -1;
if (y <= 0 && diry == -1)
diry *= -1;
if (y + 10 >= py && y <= py + ly && diry == 1 && x + 10 >= px && x <= px + lx)
diry *= -1;
}
int getX() {
return x;
}
int getY() {
return y;
}
void setDirx(){
dirx *= -1;
}
void setDiry(){
diry *= -1;
}
void move() {
x += speed*dirx;
y += speed*diry;
}
void paint(Graphics2D g) {
g.fillOval(x,y,10,10);
}
}
public class Paddle {
private
int x = 400;
int y = 520;
int width = 100;
int height = 6;
int speed = 6;
int dirL = 0;
int dirR = 0;
public
void move() {
x -= speed*dirL;
x += speed*dirR;
}
void stop() {
if (x <= 0)
x = 0;
if (x + width >= 800)
x = 800 - width;
}
int getX() {
return x;
}
int getY() {
return y;
}
int getWidth() {
return width;
}
int getHeight() {
return height;
}
void paint(Graphics2D g) {
g.fillRect(x,y,width,height);
}
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_LEFT)
dirL = 0;
else if (e.getKeyCode() == KeyEvent.VK_RIGHT)
dirR = 0;
else {
dirL = 0;
dirR = 0;
}
}
public void keyPressed(KeyEvent e) {
switch(e.getKeyCode()) {
case KeyEvent.VK_LEFT:
dirL = 1;
break;
case KeyEvent.VK_RIGHT:
dirR = 1;
break;
}
}
}
public class Brick {
private
int x;
int y;
int width;
int height;
boolean alive;
boolean inX = false,inY = false;
public
void setUpBrick(int px, int py, int w, int h, boolean al) {
x = px;
y = py;
width = w;
height = h;
alive = al;
}
void setAlive(boolean alive) {
this.alive = alive;
}
void paint(Graphics2D g) {
if (alive)
g.fillRect(x,y,width,height);
}
boolean collision(int bx, int by) {
if (alive) {
if (bx + 10 >= x && bx <= x + width && by + 10 >= y && by <= y + height) {
setAlive(false);
return true;
} else return false;
}
else return false;
}
void inAreaX(int bx) {
if (bx + 10 >= x && bx <= x + width) {
System.out.println("inAreaX");
inX = true;
} else {
inX = false;
}
}
void inAreaY(int by) {
if (by + 10 >= y && by <= y + height) {
System.out.println("inAreaY");
inY = true;
} else {
inY = false;
}
}
boolean isInAreaX () {
if (inX)
return true;
else return false;
}
boolean isInAreaY () {
if (inY)
return true;
else return false;
}
}
Ball ball = new Ball();
Paddle paddle = new Paddle();
Brick[][] brick = new Brick[8][4];
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 4; j++) {
brick[i][j].setUpBrick(j * 101, i * 51, 100, 50, true);
}
}
void bounce() {
for (int i = 0; i < 8; i++) {
for (int j = 0; j < 4; j++) {
brick[i][j].inAreaX(ball.getX());
brick[i][j].inAreaY(ball.getY());
if (brick[i][j].collision(ball.getX(), ball.getY())) {
if (brick[i][j].isInAreaX()) {
ball.setDiry();
} else if (brick[i][j].isInAreaY()) {
ball.setDirx();
}
}
}
}
}
void move() {
ball.bounce(paddle.getX(), paddle.getY(), paddle.getWidth(),paddle.getHeight());
ball.move();
paddle.move();
paddle.stop();
bounce();
}
public Breakout() {
addKeyListener(new KeyListener() {
public void keyTyped(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
paddle.keyReleased(e);
}
public void keyPressed(KeyEvent e) {
paddle.keyPressed(e);
}
});
setFocusable(true);
}
public void paint(Graphics g) {
super.paint(g);
Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setColor(Color.RED);
ball.paint(g2d);
g2d.setColor(Color.BLACK);
paddle.paint(g2d);
g2d.setColor(Color.ORANGE);
for (int i = 0; i < 8; i++)
for (int j = 0; j < 4; j++)
brick[i][j].paint(g2d);
}
public static void main(String[] args) throws InterruptedException {
JFrame window = new JFrame("Tennis");
Breakout game = new Breakout();
window.add(game);
window.setSize(800,600);
window.setVisible(true);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
while (true) {
game.move();
game.repaint();
Thread.sleep(10);
}
}
i need to inicialize 2d array of brick, but it says that first for is unexpected token. How to write it? Thank you.

Unless if I have miscounted your opening and closing braces, your for loop is not inside any method, it's directly in your class body. That's why you're getting unexpected token. You will probably want to move it into the Breakout constructor.

In order to create a 2D array in Java, you can create such an array like this:
Object testArray = new Object[10][10];
This array is now a 10*10 array with memory allocated for 100 Object references.
You can create pointers two Objects with a double for-loop:
for (int i = 0; i < testArray.length(); i++) {
for (int j = 0; j < testArray.length; j++) {
testArray[i][j] = Object; //here you input the objects that you want to point to
}
}

Move the logic from setUpBrick to a constructor.
public class Brick {
private int x;
private int y;
private int width;
private int height;
private boolean alive;
private boolean inX = false,inY = false;
public Brick(int px, int py, int w, int h, boolean al) {
x = px;
y = py;
width = w;
height = h;
alive = al;
}
...
}
Then change
brick[i][j].setUpBrick(j * 101, i * 51, 100, 50, true);
to
brick[i][j] = new Brick(j*101, i*51, 100, 50, true);
Also note that access modifiers don't apply to a whole section of your class. In your example,
private
int x;
int y;
int width;
int height;
boolean alive;
boolean inX = false,inY = false;
means that only x is going to be private. The rest of the members will get the default access modifier.
One more tip. A couple of your methods can be simplified.
boolean isInAreaY () {
if (inY)
return true;
else return false;
}
can be written as:
boolean isInAreaY() {
return inY;
}

java 2d game -lagging and collision issue

I am designing a simple java 2d game.where an aircraft shoots missiles and they hit alien ships.(pictures are attached for a better understanding).
Now I need to detect when the missile hits the alien ship. So as to count the number of total hits. I used the rectangle1.intersects(rec2)method, but instead of giving me an integer 1 as the answer (after the boolean of course) it gives me some funny answer. I guess like how much the two rectangles intersect...
Also when adding new aliens in an arraylist I use the following: I add new aliens every two seconds, but this slows down the game very much.
So please guide me on these two issues.
There is a game class (contains the main frame), board class (the panel on which I draw) alient, missile and craft class. Below I am giving the the actionPerformed() of the panel class which gets called by a timer every 2ms (the rest of the code is below).
///CODE TO BE FOCUSED ON
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import javax.swing.*;
public class game extends JFrame {
static long z;
game()
{
add(new board());
setBounds(0, 0, 500, 500);
setVisible(true);
setLayout(null);
setLocationRelativeTo(null);
setTitle("\t\t...................::::~~~~'S GAME~~~~:::::...............");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public static void main(String[] args) {
new game();
z = System.currentTimeMillis();
}
}
class board extends JPanel implements ActionListener
{
Timer t = new Timer(5, this);
public ArrayList alien_list;
craft craft_list = new craft();
Label l = new Label();
int total_hits = 0;
public board() {
setFocusable(true);
setLayout(null);
setDoubleBuffered(true);
setBackground(Color.BLACK);
addKeyListener(craft_list);
l.setBounds(0, 0, 150, 30);
l.setBackground(Color.GREEN);
add(l);
t.start();
alien_list = new ArrayList();
alien_list.add(new alien(0, 100));
alien_list.add(new alien(0, 150));
alien_list.add(new alien(0, 200));
}
public void paint(Graphics g) {
super.paint(g);
Graphics2D g1 = (Graphics2D) g;
long z = (System.currentTimeMillis() - game.z) / 1000;
if (z >= 60)
{
remove(l);
g.setColor(Color.red);
g1.drawString("time up", 100, 100);
} else
{
g1.drawImage(craft_list.getImage(), craft_list.getX(),
craft_list.getY(), null);
ArrayList a = craft_list.getmissile();
for (int i = 0; i < a.size(); i++) {
missile m = (missile) a.get(i);
g1.drawImage(m.getImage(), m.getX(), m.getY(), null);
}
l.setText("time elapsed:" + " " + +z + " " + "hits:" + " "
+ total_hits);
for (int i = 0; i < alien_list.size(); i++) {
alien m = (alien) alien_list.get(i);
g1.drawImage(m.getImage(), m.getX(), m.getY(), null);
}
}
}
public void actionPerformed(ActionEvent e) {
ArrayList a = craft_list.getmissile();
for (int i = 0; i < a.size(); i++) {
missile m = (missile) a.get(i);
if (m.visible == true)
m.move();
else
a.remove(i);
}
long z = (System.currentTimeMillis() - game.z) / 1000;
if (z % 3 == 0)
alien_list.add(new alien(-10, 100));
for (int j = 0; j < alien_list.size(); j++) {
alien m = (alien) alien_list.get(j);
if (m.visible == true)
m.move();
else
alien_list.remove(j);
}
craft_list.move();
collison();
repaint();
}
public void collison() {
ArrayList a = craft_list.getmissile();
for (int i = 0; i < a.size(); i++) {
missile m = (missile) a.get(i);
Rectangle r1 = m.getBounds();
for (int j = 0; j < alien_list.size(); j++) {
alien l = (alien) alien_list.get(j);
Rectangle r2 = l.getBounds();
if (r1.intersects(r2)) {
total_hits++;
m.setVisible(false);
l.setVisible(false);
}
}
}
}
}
class craft extends KeyAdapter
{
int x = 250;
int y = 400;
ArrayList m = new ArrayList();
Image i;
int dx, dy;
craft() {
ImageIcon i1 = new ImageIcon("1a.jpg");
i = i1.getImage();
}
public Image getImage() {
return i;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
public void move() {
x += dx;
y += dy;
if (x < 0)
x = 0;
if (x > 450)
x = 450;
if (y > 420)
y = 420;
if (y < 200)
y = 200;
}
public void keyPressed(KeyEvent k)
{
int key = k.getKeyCode();
if (key == KeyEvent.VK_SPACE) {
fire();
}
if (key == KeyEvent.VK_LEFT) {
dx = -1;
}
if (key == KeyEvent.VK_RIGHT) {
dx = 1;
}
if (key == KeyEvent.VK_UP) {
dy = -1;
}
if (key == KeyEvent.VK_DOWN) {
dy = 1;
}
}
public void keyReleased(KeyEvent e) {
int key = e.getKeyCode();
if (key == KeyEvent.VK_LEFT) {
dx = 0;
}
if (key == KeyEvent.VK_RIGHT) {
dx = 0;
}
if (key == KeyEvent.VK_UP) {
dy = 0;
}
if (key == KeyEvent.VK_DOWN) {
dy = 0;
}
}
public void fire() {
m.add(new missile(getX() + 13, getY() - 6));
}
public ArrayList getmissile() {
return m;
}
public Rectangle getBounds() {
return new Rectangle(x, y, i.getWidth(null), i.getHeight(null));
}
}
class missile {
Image i;
int x, y;
public boolean visible;
missile(int x, int y) {
this.x = x;
this.y = y;
visible = true;
ImageIcon i1 = new ImageIcon("1c.jpg");
i = i1.getImage();
}
public Image getImage() {
return i;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
public void move() {
y--;
if (y < 0)
visible = false;
}
public Rectangle getBounds() {
return new Rectangle(x, y, i.getWidth(null), i.getHeight(null));
}
public void setVisible(boolean t) {
this.visible = t;
}
}
class alien {
Image i;
int x, y;;
public boolean visible;
public alien(int x, int y)
{
this.x = x;
this.y = y;
ImageIcon i1 = new ImageIcon("b.jpg");
i = i1.getImage();
visible = true;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
public Image getImage() {
return i;
}
public void move() {
x++;
if (x > 500)
visible = false;
}
public Rectangle getBounds() {
return new Rectangle(x, y, i.getWidth(null), i.getHeight(null));
}
public void setVisible(boolean t) {
this.visible = t;
}
}

Ok, your code format is kind of unreadable and invites everybody to oversee otherwise obvious bugs. That is what I have seen so far for your performance issue:
getBounds() creates a new Rectangle instance every time it gets called. You should update the bounds rectangle at the last line of your move() and just return the rectangle instance instead of creating a new one.
Reuse Image or ImageIcon objects. There is no need to load the same jpg file over and over again in a constructor. Make it static or use a image cache.
Instead of o++ in fire() you should use o = m.size(). Mainly because you never call o--, you only remove the rocket from the ArrayList.
And at that point everybody loses track of what o and m means. Name your variables better! o should be amountOfRockets and m should be listOfRockets.
When you use Eclipse, press ctrl + shift + f to format the code which I highly recommend. After that go through your code and name the variables correctly. That means you should give them a descriptive name. And finally: let the name of your classes start with an upper case.
Very likely that this will not yet remove all issues but it will at least help us to understand and read your code easier... which might lead us to a solution...
Update:
You still haven't done 1. and 2. I suggested but you did 3.
Here is what 1. should be as a sample for the Alien class:
private Rectangle bounds
//constructor
Alien() {
// your stuff and the bounds:
bounds = new Rectangle(x, y, i.getWidth(null), i.getHeight(null));
}
public void move() {
bounds.x++;
if (bounds.x > 500)
visible = false;
}
public Rectangle getBounds() {
return bounds;
}
You need to implement that for the Rocket class as well.
What I still don't get is where you remove the old Alien objects. Just setting their visibility is not enough. You should remove them from the list of your Alien objects. Otherwise you will loop through objects that are not there anymore.