[英]How do I make it so the circle in this frame actually moves automatically?
我無法解決這個問題。 我用所需的輸出創建了該框架和面板。 唯一的事情是我無法弄清楚如何使球“自動”移動。 我理想的游戲可能是在游戲開始時就放下了球/圓,可能是單擊了按鈕或類似的按鈕。 我將如何去做呢?
我嘗試用E鍵移動球,但是這對於用戶來說太不方便了,因此我認為沒有事件處理程序的情況下移動球是更好的選擇。
private int ballX, ballY, ballR;
private int score1, score2;
private JPanel panel;
private JFrame frame;
private DrawingArea canvas;
private int xpos, ypos,width,height;
private int xpos2, ypos2, width2, height2;
public Pong(){
xpos = 300;
ypos = 550;
width = 100;
height = 50;
xpos2 = 300;
ypos2 = 100;
width2 = 100;
height2 = 50;
ballR = 50;
ballX = 325;
ballY = 330;
}
public static void main(String[]args){
Pong p = new Pong();
p.run();
}
public void run(){
frame = new JFrame("Pong");
frame.setSize(700,700);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
canvas = new DrawingArea(); // create a panel to draw on
canvas.setBackground(Color.WHITE);
canvas.addFocusListener(this);
canvas.addKeyListener(this);
canvas.addMouseListener(this);
frame.getContentPane().add(canvas);
frame.setVisible(true);
}
class DrawingArea extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor ( Color.blue );
g.fillRect ( xpos, ypos, width, height );
g.setColor(Color.red);
g.fillRect(xpos2, ypos2, width2, height2);
g.setColor(Color.black);
g.fillRect(0,0,700,50);
g.fillRect(0,630,700,50);
g.fillOval(ballX,ballY,ballR, ballR);
}
}
public void keyPressed ( KeyEvent e ) {
int value = e.getKeyCode();
switch ( value ) {
case KeyEvent.VK_RIGHT: xpos += 50; break;
case KeyEvent.VK_LEFT: xpos -= 50; break;
case KeyEvent.VK_A: xpos2 -= 50; break;
case KeyEvent.VK_D: xpos2 += 50; break;
/*try to drop the ball with the space button
* case KeyEvent.VK_SPACE:
ballX+=25;
ballY+=25;
break;
case KeyEvent.VK_ENTER:
xpos = (int)( Math.random ( ) * ( 500 - (2 * radius) ) );
ypos = (int)( Math.random ( ) * ( 500 - (2 * radius) ) );
break;
*/
}
if( (xpos < 0 || xpos >= 700) || (xpos2 < 0 || xpos2 >= 700)){
if(xpos < 0 || xpos2 < 0){
if(xpos < 0) xpos = 0;
else if(xpos2 < 0) xpos2 = 0;
return;
}
else if(xpos >= 700 || xpos2 >= 700){
if(xpos >= 700)xpos = 550;
else if(xpos2 >= 700) xpos2=550;
return;
}
}
canvas.repaint ( );
}
}
我希望輸出會隨着游戲開始/按下按鈕而使球下降到藍色矩形上,但是我無法使其正常工作。
當您要自動移動球時,請在run()方法中使用一些增量值(如您在keyPressed()接口方法中所做的那樣)更改dx,dy等,以改變球的位置(您的xpos,ypos,xpos1和ypos2)。並調用JFrame的repaint()方法。
public class BouncingBall extends JPanel {
// Box height and width
int width;
int height;
// Ball Size
float radius = 40;
float diameter = radius * 2;
// Center of Call
float X = radius + 50;
float Y = radius + 20;
// Direction
float dx = 3;
float dy = 3;
public BouncingBall() {
Thread thread = new Thread() {
public void run() {
while (true) {
width = getWidth();
height = getHeight();
X = X + dx ;
Y = Y + dy;
if (X - radius < 0) {
dx = -dx;
X = radius;
} else if (X + radius > width) {
dx = -dx;
X = width - radius;
}
if (Y - radius < 0) {
dy = -dy;
Y = radius;
} else if (Y + radius > height) {
dy = -dy;
Y = height - radius;
}
repaint();
try {
Thread.sleep(50);
} catch (InterruptedException ex) {
}
}
}
};
thread.start();
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.BLUE);
g.fillOval((int)(X-radius), (int)(Y-radius), (int)diameter, (int)diameter);
}
public static void main(String[] args) {
JFrame.setDefaultLookAndFeelDecorated(true);
JFrame frame = new JFrame("Bouncing Ball");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(300, 200);
frame.setContentPane(new BouncingBall());
frame.setVisible(true);
}
}
由於我在Thread.sleep()中使用了50毫秒的渲染時間,因此您可以指定自己的時間。 因此,對於我來說,每50毫秒您的JFrame都會更新一次。
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