Add second year

second/semester2/CT255/Assignments/Assigment-03/InvadersApplication.java

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+import java.awt.*;
+import java.awt.event.*;
+import javax.swing.*;
+
+public class InvadersApplication extends JFrame implements Runnable, KeyListener {
+    // member data
+    private static String workingDirectory = System.getProperty("user.dir");
+    
+    private Image alienImage;
+    private Image playerImage;
+
+    private static final Dimension WindowSize = new Dimension(600, 600); 
+    private static final int NUMALIENS = 30; 
+    private Alien[] AliensArray = new Alien[NUMALIENS]; 
+    private Player player;
+
+    // variable to hold how far the player should be moving in the x axis per frame - default 0. 
+    private int dx = 0; 
+
+    // constructor 
+    public InvadersApplication() {
+        // set up window
+        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
+
+        // display the window. centred on the screen
+        Dimension screensize = java.awt.Toolkit.getDefaultToolkit().getScreenSize(); int x = screensize.width/2  - WindowSize.width/2; int y = screensize.height/2 - WindowSize.height/2;
+        setBounds(x, y, WindowSize.width, WindowSize.height);
+
+        // adding a key listener
+        addKeyListener(this);
+
+        // load image from disk 
+        ImageIcon alienIcon = new ImageIcon(workingDirectory + "/alien_ship_1.png");
+        ImageIcon playerIcon = new ImageIcon(workingDirectory + "/player_ship.png");
+
+        alienImage = alienIcon.getImage();
+        playerImage = playerIcon.getImage();
+        
+        // instantiating an alien for each index in the aliens array
+        for (int i = 0; i < NUMALIENS; i++) {
+            AliensArray[i] = new Alien(alienImage);
+
+            // generating a random starting position for the alien
+            AliensArray[i].setPosition((int) (Math.random()*600), (int) (Math.random()*600));
+        }
+
+        // creating a player icon & setting it's position 
+        player = new Player(playerImage);
+        player.setPosition(270, 550);
+
+        setVisible(true);
+
+        // create a new thread & start it 
+        Thread t = new Thread(this);
+        t.start();
+    }
+
+    // thread's entry point
+    public void run() {
+        while (true) {
+            // repainting 
+            this.repaint();
+
+            try {
+                Thread.sleep(20); 
+            } catch (InterruptedException e) {
+                e.printStackTrace(); 
+            } 
+        }
+    }
+
+    @Override
+    public void keyPressed(KeyEvent e) {
+        // getting the keycode of the event 
+        int key = e.getKeyCode();
+
+        // if right key pressed, making the distance to be moved 10px to the right 
+        if (key == KeyEvent.VK_RIGHT) {
+            dx = 5;
+        }
+        // if left key pressed, making the distance to be moved 10px to the left
+        if (key == KeyEvent.VK_LEFT) {
+            dx = -5;
+        }
+    }
+
+    @Override
+    public void keyReleased(KeyEvent e) {
+        // getting the keycode of the event 
+        int key = e.getKeyCode();
+
+        // if the key released was the left or right arrow, setting dx back to 0
+        if (key == KeyEvent.VK_RIGHT || key == KeyEvent.VK_LEFT) {
+            dx = 0;
+        }
+    }
+
+    @Override 
+    public void keyTyped(KeyEvent e) {
+    }
+
+    // application's paint method
+    public void paint(Graphics g) {
+        // draw a black rectangle on the whole canvas 
+        g.setColor(Color.BLACK); 
+        g.fillRect(0, 0, 600, 600);
+
+        // iterating through each sprite, moving it, and calling it's paint method 
+        for (Alien a : AliensArray) {
+            a.move();
+            a.paint(g);
+        }
+
+        // moving the player dx pixels - should be 0 if no key is being pressed 
+        player.move(dx); 
+
+        // calling the Player's paint method 
+        player.paint(g);
+    }
+
+    // application entry point 
+    public static void main(String[] args) {
+        InvadersApplication ia = new InvadersApplication(); 
+    }
+}