用戶按下Jbutton的隨機時間后的Java drawOval

Question

因此，當用戶按下我的JButton時，它將隨機選擇一個時間，然后在該時間之后，它將在屏幕上繪制一個橢圓形。 但是，對於我現在所擁有的，它在按下按鈕后立即繪制了橢圓形。 我希望它在隨機時間后出現。

  public void actionPerformed(ActionEvent e) 
  {
  if (e.getSource() == startButton)
  {
      popUpTime = random.nextInt(5000);
      timer = new Timer(popUpTime, this);

      x = random.nextInt(400) + 70;
          y = random.nextInt(400) + 100;

          points[current++] = new Point(x, y);

      timer.start();
      start();

      repaint();
  }


   }

Answer 1

問題是您的邏輯：

if event is start button, then setup oval and timer and call repaint();

假定重新繪制是在設置的坐標處繪制橢圓形。

您可能應該執行以下操作：

if (e.getSource() == startButton)  {
  drawOval = false;  // flag to repaint method to NOT display oval
  // setup timer 
  repaint();  // oval will not be drawn
else {
  // assuming timer has fired (which is a bit weak)
  x = ....;
  y = ...;
  drawOval = true;
  repaint();  // oval will be drawn.
}

您的repaint（）方法將需要檢查drawOval設置：

public void repaint() {
  if (drawOval) {
    // draw it
  } else {
    // may need to clear oval
  }

  // draw other stuff.
}

Answer 2

您可以使用Thread類中的sleep函數使程序等待隨機時間。 像這樣：

try{
Thread.sleep(PopUpTime);
}
catch(Exception e)
{}
// and then compute new points and repaint