Basic Games (with Swing and AWT UI)
Make a character to control
import java.awt.Image;
public class Hero {
private Image sprite;
private int x = 0;
private int y = 0;
private int xVelocity = 0;
private int yVelocity = 0;
public Hero(Image sprite, int x, int y) {
this.sprite = sprite;
this.x = x;
this.y = y;
}
public void update () {
this.x += this.xVelocity;
this.y += this.yVelocity;
}
public int getX() { return this.x; }
public int getY() { return this.y; }
public void setXVel(int setTo) { this.xVelocity = setTo; }
public void setYVel(int setTo) { this.yVelocity = setTo; }
public Image getSprite() { return this.sprite; }
}
- This keeps track of the position and velocity, and stores its image
- The game class (defined below) will create a hero object and make it move with keyboard inputs
Make an item to collect
import java.awt.Image;
public class Collectable {
private Image sprite;
private int x = 0;
private int y = 0;
public Collectable(Image sprite, int x, int y) {
this.sprite = sprite;
this.x = x;
this.y = y;
}
public int getX() { return this.x; }
public int getY() { return this.y; }
public void setX (int setTo) {this.x = setTo;}
public void setY (int setTo) {this.y = setTo;}
public Image getSprite() { return this.sprite; }
}
- This keeps track of its position, and stores its image
Define the game
public class SimpleGame {
private Hero player1;
private ArrayList<Collectable> collectables;
public SimpleGame () {
try {
// Initialize player 1
Image heroSprite = new ImageIcon("demoImage.png").getImage();
player1 = new Hero(heroSprite,100,100);
// Initialize 2 collectables
collectables = new ArrayList<Collectable>();
Image colSprite = new ImageIcon("collectable.png").getImage();
collectables.add( new Collectable(colSprite,40,30));
collectables.add( new Collectable(colSprite,140,230));
}
catch (Exception e) {
e.printStackTrace();
}
}
// Define the game loop
public void update () {
player1.update();
// If player 1 reaches a collectable, reset its position
for (Collectable coll : collectables) {
if ( Math.abs(player1.getX() - coll.getX()) < 64
&& Math.abs(player1.getY() - coll.getY()) < 64)
{
coll.setX( (int)(Math.random() * 350) );
coll.setY( (int)(Math.random() * 350) );
}
}
}
// Display game objects and player 1
public void display (Graphics2D g) {
for (Collectable obj : collectables) {
g.drawImage(obj.getSprite(), obj.getX(), obj.getY(), null);
}
g.drawImage(player1.getSprite(), player1.getX(), player1.getY(), null);
}
// Define actions for direction keys
public void onLeftKeyPress() {
player1.setXVel(-6);
player1.setYVel(0);
}
public void onRightKeyPress() {
player1.setXVel(6);
player1.setYVel(0);
}
public void onUpKeyPress() {
player1.setXVel(0);
player1.setYVel(-6);
}
public void onDownKeyPress() {
player1.setXVel(0);
player1.setYVel(6);
}
}
- Import java.awt.Graphics2D, java.awt.Image, java.util.ArrayList, and javax.swing.ImageIcon
- For every step of the game, the hero's position will be updated; if he reaches a collectable, it will jump to a new position
- For better encapsulation, the game display function and key action functions are defined here
Set up the UI
public class SimpleGamePanel extends JPanel implements ActionListener {
SimpleGame game;
public SimpleGamePanel(SimpleGame game) {
this.game = game;
try {
this.setBackground(Color.blue);
Timer timer = new Timer (100, this);
timer.start();
}
catch (Exception e) {
e.printStackTrace();
}
PressRightAction pressRightAction = new PressRightAction();
this.getInputMap().put(KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT,0, false), "pressRight");
this.getActionMap().put("pressRight", pressRightAction );
PressLeftAction pressLeftAction = new PressLeftAction();
this.getInputMap().put(KeyStroke.getKeyStroke(KeyEvent.VK_LEFT,0, false), "pressLeft");
this.getActionMap().put("pressLeft", pressLeftAction );
PressUpAction pressUpAction = new PressUpAction();
this.getInputMap().put(KeyStroke.getKeyStroke(KeyEvent.VK_UP,0, false), "pressUp");
this.getActionMap().put("pressUp", pressUpAction );
PressDownAction pressDownAction = new PressDownAction();
this.getInputMap().put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN,0, false), "pressDown");
this.getActionMap().put("pressDown", pressDownAction );
}
@Override
public void actionPerformed (ActionEvent event) {
game.update();
repaint();
}
public void paint (Graphics gra) {
Graphics2D g = (Graphics2D) gra;
super.paint(g);
game.display(g);
}
// Define the action to be performed when key is pressed
public class PressRightAction extends AbstractAction {
@Override
public void actionPerformed (ActionEvent ae) {
game.onRightKeyPress();
}
}
public class PressLeftAction extends AbstractAction {
@Override
public void actionPerformed (ActionEvent ae) {
game.onLeftKeyPress();
}
}
public class PressUpAction extends AbstractAction {
@Override
public void actionPerformed (ActionEvent ae) {
game.onUpKeyPress();
}
}
public class PressDownAction extends AbstractAction {
@Override
public void actionPerformed (ActionEvent ae) {
game.onDownKeyPress();
}
}
}
- Import these from java.awt: Color, Graphics, Graphics2D, event.ActionEvent, event.ActionListener, event.KeyEvent;
- Import these from javax.swing: AbstractAction, JPanel, KeyStroke, Timer
- The keyboard actions are defined here and connected with the functions defined in the game class
- The graphics object is passed to the game's display function to handle it
Completed