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

public class text extends JFrame {

    private JLabel panelNorth;
    private JPanel panelSouth;
    private JButton but_start;
    private JButton but_out;
    private JPanel pan;
    private BorderLayout lay;

    public text() {
        setTitle("面板");
        lay = new BorderLayout();
        setLayout(lay);
        lay.setVgap(15);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(400, 100, 500, 550);
        init();
        setVisible(true);
    }

    void init() {
        panelNorth = new JLabel("画线！");
        panelNorth.setFont(new Font("楷体", 30, 24));
        panelNorth.setForeground(Color.blue);
        this.getContentPane().add(panelNorth, BorderLayout.NORTH);

        panelSouth = new JPanel();
        but_start = new JButton("开始");
        but_out = new JButton("退出");
        but_start.setFont(new Font("楷体", 10, 16));
        but_out.setFont(new Font("楷体", 10, 16));
        panelSouth.add(but_start);
        panelSouth.add(but_out);
        this.getContentPane().add(panelSouth, BorderLayout.SOUTH);

        pan = new JPanel() {

            @Override
            public void paintComponent(Graphics g) {
                super.paintComponent(g);
                g.setColor(Color.black);
                g.drawLine(50, 50, 100, 100);
            }
        };
        this.getContentPane().add(pan, BorderLayout.CENTER);
    }

    public static void main(String args[]) {
        new text();
    }
}