简单计算器实现

基本思路:边输入边计算，最后显示

import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javafx.scene.layout.Border;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Calculator extends JFrame {
private boolean start, flag;
private String lastCommand;
private double result1, result2;
private int count=1;
JButton display;
JPanel panel;

public Calculator() {    setLayout(new BorderLayout());    result1 = 0;    result2 = 0;    start = true;    flag = false;    lastCommand = "=";    display = new JButton(" ");    display.setEnabled(false);    add(display, BorderLayout.NORTH);    ActionListener insert = new InsertAction();    ActionListener command = new CommandListener();    panel = new JPanel(new GridLayout(4, 4));    addButton("7", insert);    addButton("8", insert);    addButton("9", insert);    addButton("/", command);    addButton("4", insert);    addButton("5", insert);    addButton("6", insert);    addButton("*", command);    addButton("1", insert);    addButton("2", insert);    addButton("3", insert);    addButton("-", command);    addButton("0", insert);    addButton(".", insert);    addButton("=", command);    addButton("+", command);    add(panel, BorderLayout.CENTER);    pack();    setTitle("Calculator");    setResizable(false);    setSize(300, 200);    setLocation(400, 400);    setVisible(true);    setDefaultCloseOperation(this.EXIT_ON_CLOSE);}private void addButton(String label, ActionListener listener) {    Button button = new Button(label);    button.addActionListener(listener);    panel.add(button);}private class InsertAction implements ActionListener {// 监听数字按钮    public void actionPerformed(ActionEvent e) {        String input = e.getActionCommand();        display.setText(display.getText() + input);    }}private class CommandListener implements ActionListener {// 监听命令按钮    public void actionPerformed(ActionEvent e) {        String command = e.getActionCommand();        if (flag) {            String[] s;            s = display.getText().split("\\" + lastCommand);            result2 = Double.parseDouble(s[s.length-1]);            System.out.println(result2);            calculator();            if (command.equals("="))                display.setText("" + result1);            else                display.setText(display.getText() + command);            lastCommand = command;            //flag = false;        } else {            result1 = Double.parseDouble(display.getText());            display.setText(display.getText() + command);            lastCommand = command;            flag = true;        }    }}public void calculator() {// 进行计算的函数    if (lastCommand.equals("+")) {        result1 += result2;    } else if (lastCommand.equals("-")) {        result1 -= result2;    } else if (lastCommand.equals("*")) {        result1 *= result2;    } else if (lastCommand.equals("/")) {        result1 /= result2;    } else if (lastCommand.equals("=")) {        result1 = result2;    }}public static void main(String[] args) {    new Calculator();}

}