JAVA实现四则运算计算器

public class Calculator {//主类........
    public static void main (String [] args) {
        
        MyFrame mf = new MyFrame ("Shinn");
        mf.info();
        
    }
}
class MyFrame extends Frame{
    Calculate cal = new Calculate ();//计算部分的类....
    boolean start = true;//判断是否为没输入数字...
    String s;//BAC用的中间String
    boolean sum = false;
    JButton b0 = new JButton("0");//按钮
    JButton b1 = new JButton ("1");
    JButton b2 = new JButton ("2");
    JButton b3 = new JButton ("3");
    JButton b4 = new JButton ("4");
    JButton b5 = new JButton ("5");
    JButton b6 = new JButton ("6");
    JButton b7 = new JButton ("7");
    JButton b8 = new JButton ("8");
    JButton b9 = new JButton ("9");
    JButton bp = new JButton ("+");
    JButton bd = new JButton ("-");
    JButton bm = new JButton ("*");
    JButton be = new JButton ("/");
    JButton bce = new JButton ("CE");
    JButton bc = new JButton ("Bac");
    JButton beq = new JButton ("=");

    JButton bpo = new JButton (".");
    JButton blm = new JButton ("(");
    JButton brm = new JButton (")");
    JTextField tf = new JTextField ("0");
    JTextField tfs = new JTextField("");
    MyFrame (String s ){//窗体....
        super(s);
        setBackground(Color.GRAY);
        setBounds(500, 300, 300, 200);
        setResizable(false);
    }
    public void info (){//窗体初始化....
        tf.setHorizontalAlignment(JTextField.RIGHT);
        tfs.setHorizontalAlignment(JTextField.RIGHT);
        tf.setEditable(false);
        tfs.setEditable(false);
        setLayout(new BorderLayout());
        Panel p1 = new Panel(new BorderLayout());
        Panel p2 = new Panel(new GridLayout(4,5));
        p1.add(tf,BorderLayout.CENTER);
        p1.add(tfs,BorderLayout.NORTH);
        p2.add(b1);
        p2.add(b2);
        p2.add(b3);
        p2.add(bp);
        p2.add(bce);
        p2.add(b4);
        p2.add(b5);
        p2.add(b6);
        p2.add(bd);