使用java设计如下界面，在界面上方有一个标签“I’m a able”,中间有一个随机颜色的圆形，下方有两个按钮，点击点击“change lable”后标签改变为“ouch!”。点击“change circle”后圆改变颜色。

好的，以下是Java Swing实现的代码示例：

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class MyFrame extends JFrame implements ActionListener {
    private JLabel label;
    private JButton labelButton;
    private JButton circleButton;
    private JPanel panel;
    private Color circleColor;

    public MyFrame() {
        // 设置窗口标题
        setTitle("My Frame");

        // 创建标签
        label = new JLabel("I'm able", JLabel.CENTER);
        label.setFont(new Font("宋体", Font.PLAIN, 24));
        label.setForeground(Color.BLACK);

        // 创建按钮
        labelButton = new JButton("Change Label");
        labelButton.addActionListener(this);
        circleButton = new JButton("Change Circle");
        circleButton.addActionListener(this);

        // 创建面板并添加组件
        panel = new JPanel(new BorderLayout());
        panel.add(label, BorderLayout.CENTER);
        JPanel buttonPanel = new JPanel(new GridLayout(1, 2));
        buttonPanel.add(labelButton);
        buttonPanel.add(circleButton);
        panel.add(buttonPanel, BorderLayout.SOUTH);

        // 创建随机颜色的圆形
        circleColor = getRandomColor();
        CirclePanel circlePanel = new CirclePanel(circleColor);
        panel.add(circlePanel, BorderLayout.NORTH);

        // 添加面板到窗口
        add(panel);

        // 设置窗口大小并居中
        setSize(400, 400);
        setLocationRelativeTo(null);
    }

    // 按钮点击事件
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == labelButton) {
            label.setText("Ouch!");
        } else if (e.getSource() == circleButton) {
            circleColor = getRandomColor();
            panel.remove(0);
            CirclePanel newCirclePanel = new CirclePanel(circleColor);
            panel.add(newCirclePanel, BorderLayout.NORTH, 0);
            panel.revalidate();
            panel.repaint();
        }
    }

    // 获取随机颜色
    private Color getRandomColor() {
        int r = (int) (Math.random() * 256);
        int g = (int) (Math.random() * 256);
        int b = (int) (Math.random() * 256);
        return new Color(r, g, b);
    }

    // 圆形面板
    private class CirclePanel extends JPanel {
        private Color color;

        public CirclePanel(Color color) {
            this.color = color;
        }

        public void paintComponent(Graphics g) {
            super.paintComponent(g);
            g.setColor(color);
            g.fillOval(50, 50, 100, 100);
        }
    }

    public static void main(String[] args) {
        MyFrame frame = new MyFrame();
        frame.setVisible(true);
    }
}

运行该程序即可看到界面。点击“Change Label”按钮可以改变标签内容，点击“Change Circle”按钮可以改变圆形颜色。