[英]Why does my jFrame update only after I resize the window?
I understand that when you add/remove a component, you need to revalidate()
and then repaint()
. 我了解在添加/删除组件时,需要先revalidate()
然后再repaint()
。 However, I am changing the state of my polygon. 但是,我正在更改多边形的状态。 Initially, the image is shown, however when I press the left and right keys, the image does not move. 最初显示图像,但是当我按左右键时,图像不会移动。 If I move the window, the gui is updated. 如果我移动窗口,则gui将更新。 Why doesn't it update as I press the keys? 为什么当我按下按键时它没有更新?
public class Terminos {
private LeftTermin ter;
private String[] commands = { "UP", "DOWN", "RIGHT", "LEFT" };
public Terminos() {
initComp();
}
public void initComp() {
JFrame jFrame = new JFrame();
jFrame.setSize(500, 500);
Component pane = new myPanel();
jFrame.add(pane);
ter = new LeftTermin(200, 200);
jFrame.addKeyListener(new KeyListener() {
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
System.out.println("r");
ter.moveR();
// Right arrow key code
} else if (e.getKeyCode() == KeyEvent.VK_LEFT) {
System.out.println("l");
ter.moveL();
// Left arrow key code
} else if (e.getKeyCode() == KeyEvent.VK_UP) {
System.out.println("u");
// Up arrow key code
} else if (e.getKeyCode() == KeyEvent.VK_DOWN) {
// Down arrow key code
System.out.println("d");
}
}
public void keyReleased(KeyEvent e) {
}
public void keyTyped(KeyEvent e) {
}
});
jFrame.revalidate();
jFrame.setVisible(true);
}
class myPanel extends JPanel {
@Override
public void paintComponent(Graphics canvas) {
super.paintComponent(canvas);
ter.draw(canvas);
}
}
}
Call repaint();
调用repaint();
after ter.moveR();moveL()
in your listener. 在ter.moveR();moveL()
之后。
Additionally I would recommentd to use KeyBindings rather than KeyListener
另外,我建议使用KeyBindings而不是KeyListener
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