[英]I am trying to make a for loop with a if statement in it to find a specific name in an arraylist
[英]I am trying to repeat an if statement using a while loop, but it keeps freezing
因此,我嘗試制作類似Snake的游戲,但遇到了一些問題。 我想使用while循環在moveup類內部重復if語句,但是當我嘗試使用KeyListener偵聽向上箭頭鍵的按鍵來打破while循環時,它的作用就像只循環了一次(向上移動了5個像素)。 該循環本應使蛇繼續向上運動而不必多次單擊,但它僅移動了五個(我為其設置的值)像素。 這是代碼:
public class Snake extends JFrame implements KeyListener {
int ballX = 50;
int ballY = 50;
int playerX = 250;
int playerY = 250;
boolean up = false;
boolean right = false;
boolean down = false;
boolean left = true;
class DrawPane extends JPanel {
public void paintComponent(Graphics gc) {
Random rand = new Random();
int dotsX = rand.nextInt(500) + 1;
int dotsY = rand.nextInt(500) + 1;
Graphics g = this.getGraphics();
setVisible(true);
super.paintComponents(gc);
gc.setColor(Color.BLUE);
gc.fillRect(ballX, ballY, 10, 10);
gc.setColor(Color.RED);
gc.fillRect(playerX, playerY, 10, 10);
}
}
public Snake(String title) {
super(title);
JFrame frame = new JFrame();
setContentPane(new DrawPane());
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.pack();
this.setSize(500, 500);
this.setBackground(Color.YELLOW);
this.setResizable(false);
this.addKeyListener(this);
}
@Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
@Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
@Override
public void keyPressed(KeyEvent e) {
// TODO Auto-generated method stub
if (e.getKeyCode() == KeyEvent.VK_UP) {
up = true;
right = false;
down = false;
left = false;
moveup(e);
}
if (e.getKeyCode() == KeyEvent.VK_DOWN) {
up = false;
right = false;
down = true;
left = false;
movedown(e);
}
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
up = false;
right = true;
down = false;
left = false;
moveright(e);
}
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
up = false;
right = false;
down = false;
left = true;
moveleft(e);
}
}
public void moveup(KeyEvent e) {
while (up) {
if (playerX < 500 || playerX > 0) {
playerX = playerX + 5;
repaint();
if (e.getKeyChar() == KeyEvent.VK_UP)
break;
}
}
}
public void moveright(KeyEvent e) {
if (playerX < 500 || playerX > 0) {
playerX = playerX + 5;
repaint();
// moveright();
}
}
public void movedown(KeyEvent e) {
if (playerY < 500 || playerY > 0) {
playerY = playerY + 5;
repaint();
// movedown();
}
}
public void moveleft(KeyEvent e) {
if (playerX < 500 || playerX > 0) {
playerX = playerX - 5;
repaint();
// moveleft();
}
}
public void snakePanel() {
JPanel panel1 = new JPanel();
panel1.setBackground(Color.red);
}
public void ActionListener() {
}
public static void main(String[] args) {
Snake r = new Snake("Snake");
}
}
它永遠不會因為中斷而循環。 您實際上是在說:
if keycode is up
loop
move up
break if keycode is up // Will always be true
更重要的是,您不應該在這樣的事件處理程序中循環。 事件處理程序應執行並快速返回,否則您將阻塞事件線程。 應該使用計時器充當心跳並定期更新位置/重繪。
請記住,您將來不想將Swing用於更高級的游戲。
---快速解決方案:
只需刪除您的while()。 通過KeyListener界面,您可以抽象出“按下此鍵的同時執行此操作”的概念。 而是在實現接口時說:“只要按下此鍵,就執行此操作”。 這是一個事件。
這是您的工作代碼:
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