Java 扣上扣子

我试着在（x，y）坐标（150210）处做一个JButton圆。我想按钮是一个椭圆形的大小（40,40）。按钮的背景颜色为红色。它不需要文本，所以我应该得到一个我想要的任意大小的按钮，对吗

我正在使用一个面板，我将setLayout设置为null：

setLayout(null)

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我查了谷歌，它把我带到了这里。我怎样才能做到这一点？

JDC技术提示：1999年8月26日：

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这在OSX10.7.5上不起作用。它是一个大的方形按钮，里面有一个圆圈。这样做效果更好：

import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;

public class RoundButton extends JButton {
  public RoundButton(String label) {
    super(label);

// These statements enlarge the button so that it 
// becomes a circle rather than an oval.
    Dimension size = getPreferredSize();
    size.width = size.height = Math.max(size.width, 
      size.height);
    setPreferredSize(size);

// This call causes the JButton not to paint 
   // the background.
// This allows us to paint a round background.
    setContentAreaFilled(false);
  }

// Paint the round background and label.
  protected void paintComponent(Graphics g) {
    if (getModel().isArmed()) {
// You might want to make the highlight color 
   // a property of the RoundButton class.
      g.setColor(Color.lightGray);
    } else {
      g.setColor(getBackground());
    }
    g.fillOval(0, 0, getSize().width-1, 
      getSize().height-1);

// This call will paint the label and the 
   // focus rectangle.
    super.paintComponent(g);
  }

// Paint the border of the button using a simple stroke.
  protected void paintBorder(Graphics g) {
    g.setColor(getForeground());
    g.drawOval(0, 0, getSize().width-1, 
      getSize().height-1);
  }

// Hit detection.
  Shape shape;
  public boolean contains(int x, int y) {
// If the button has changed size, 
   // make a new shape object.
    if (shape == null || 
      !shape.getBounds().equals(getBounds())) {
      shape = new Ellipse2D.Float(0, 0, 
        getWidth(), getHeight());
    }
    return shape.contains(x, y);
  }

// Test routine.
  public static void main(String[] args) {
// Create a button with the label "Jackpot".
    JButton button = new RoundButton("Jackpot");
    button.setBackground(Color.green);

// Create a frame in which to show the button.
    JFrame frame = new JFrame();
    frame.getContentPane().setBackground(Color.yellow);
    frame.getContentPane().add(button);
    frame.getContentPane().setLayout(new FlowLayout());
    frame.setSize(150, 150);
    frame.setVisible(true);
  }
}