Question

我想在面板上创建一个圆圈，每隔2秒出现一次并消失。这是我有：

public class Board extends JPanel implements ActionListener {

    private final int DELAY = 2000;

    private Timer timer;

    /*
     * constructor
     */
    public Board() {

        setFocusable(true);
        initGame();
    }

    /*
     * initialize board
     */
    public void initGame() {

        timer = new Timer(DELAY, this);
        timer.start();

    }

    public void paint(Graphics g) {

        super.paint(g);
        g.setColor(Color.gray);
        // draw an oval starting at 20,20 with a width and height of 100 and
        // fill it
        g.drawOval(20, 20, 100, 100);
        g.fillOval(20, 20, 100, 100);

        g.dispose();
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        repaint();
    }
}

谢谢你们。现在我想控制我的圈子。但又有些事情是错的，并没有像我想的那样移动。

这里有新方法：

    private boolean left = false;
private boolean right = true;
private boolean up = false;
private boolean down = false;

private Timer timer;

public int x = 20;
public int y = 20;
public int x2 = 100;
public int y2 = 100;

...

    public void paint(Graphics g) {

    super.paint(g);
    if (drawCircle) {
        g.setColor(Color.gray);
        // draw an oval starting at 20,20 with a width and height of 100 and
        // fill it
        g.drawOval(x, y, x2, y2);
        g.fillOval(x, y, x2, y2);
    }
    // removes native non-Java recourses
    g.dispose();
}

public void move() {

    if (left) {
        x -= 5;
    }
    if (right) {
        x += 5;
    }
    if (up) {
        y -= 5;
    }
    if (down) {
        y += 5;
    }
}

@Override
public void actionPerformed(ActionEvent e) {

    move();
    repaint();
}

private class TAdapter extends KeyAdapter {

    public void keyPressed(KeyEvent e) {

        int key = e.getKeyCode();

        if ((key == KeyEvent.VK_LEFT) && (!right)) {
            left = true;
            up = false;
            down = false;
        }

        if ((key == KeyEvent.VK_RIGHT) && (!left)) {
            right = true;
            up = false;
            down = false;
        }

        if ((key == KeyEvent.VK_UP) && (!down)) {
            up = true;
            right = false;
            left = false;
        }

        if ((key == KeyEvent.VK_DOWN) && (!up)) {
            down = true;
            right = false;
            left = false;
        }
    }
}

/ * ** * / 解决了，我刚刚补充

addKeyListener(new TAdapter());

到我的董事会建设者！

Answer 1

您只需要让Timer修改某个州。尝试这样的事情：

private boolean drawCircle = false;

public void actionPerformed(ActionEvent e) {
    drawCircle = !drawCircle;
    repaint();
}

public void paintComponent(Graphics g) {
    //...
    if ( drawCircle ) {
       g.setColor(Color.gray);
       //...
    }
}

Answer 2

你不应该提出这个问题......作为一个问题吗？

无论如何，在你的类中添加一个布尔值，在每个动作事件上切换它，并且只在它是真的时才绘制椭圆。

编辑/备注： - 覆盖paintComponent而不是paint - 请勿丢弃尚未创建的图形。删除该行，或使用g.create（）进行复制。有关详细信息，请参阅http://java.sun.com/products/jfc/tsc/articles/swing2d/。

Swing Timer with Graphics组件

2 个答案: