自己写的JAVA小计算器

package guipackage;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Listener extends JFrame implements 
ActionListener{
int resultnumber = -2147483648;
boolean flag = false;
boolean jia = false;
boolean jian = false;
boolean chen = false;
boolean chu = false;
boolean equal = false;//按+前是否按=
boolean flag2 = false;//按数字之前是否有过算术符号，有就先清零再输入
JFrame f;
JTextField tf;
JButton bt1,bt2,bt3,bt4,bt5,bt6,bt7,bt8,bt9,bt10,bt11,bt12,bt13,bt14,bt15,bt16;
JPanel p,p2 ;
 JMenuBar bar = new JMenuBar();
JMenu maker = new JMenu("选项");
 JMenuItem producer = new JMenuItem("制作人");
 JOptionPane op = new JOptionPane();
public Listener(){
f = new JFrame("计算器");
p = new JPanel();
p2 = new JPanel();
f.add(p,"North");
f.add(p2,"Center");
f.setJMenuBar(bar);
tf = new JTextField(18);

 bar.add(maker);
 maker.add(producer);
 tf.setHorizontalAlignment(JTextField.RIGHT);
 tf.setFont(new Font("宋体",Font.BOLD,22));

bt1 = new JButton("1");bt2 = new JButton("2");bt3 = new JButton("3");
bt4 = new JButton("4");bt5 = new JButton("5");bt6 = new JButton("6");
bt7 = new JButton("7");bt8 = new JButton("8");bt9 = new JButton("9");
bt10 = new JButton("0");bt11 = new JButton("+");bt12 = new JButton("-");
bt13 = new JButton("*");bt14 = new JButton("÷");bt15 = new JButton("c");
bt16 = new JButton("=");

p2.setLayout(new GridLayout(4,4));
p.add(tf);p2.add(bt1);p2.add(bt2);p2.add(bt3);
p2.add(bt11);//+
p2.add(bt4);p2.add(bt5);p2.add(bt6);
p2.add(bt12);//-
p2.add(bt7);p2.add(bt8);p2.add(bt9);
p2.add(bt13);//*
p2.add(bt15);//C
p2.add(bt10);
p2.add(bt16);//=
p2.add(bt14);//÷

bt11.setBackground(Color.ORANGE);
bt12.setBackground(Color.ORANGE);
bt13.setBackground(Color.ORANGE);
bt16.setBackground(Color.ORANGE);
bt14.setBackground(Color.ORANGE);
bt15.setBackground(Color.PINK);