​编写Java GUI程序，实现一个简单计算器。要求如下： ‍ ​（1）设计的界面如下图所示：窗体的标题栏显示“模拟计算器—江海大”，1个文本框用于显示输入字符和计算结果；20个按钮控件作为字符输入按键或者功能按键。程序的外观对64开平方根的运行结果 ‍ ​（2）计算功能：实现加、减、乘、除等双目运算，开平方、百分数等单目运算； ‍ ​（3）辅助功能：按钮“C”清空文本框；按钮“←”退格，删除文本框中最右边的一个字符。 ‍ ‍ ​

以下是一个简单的 Java GUI 程序，实现了一个简易计算器的功能，包括加、减、乘、除、开平方、百分数、清空和退格功能。 ```java import javax.swing.*; import java.awt.*; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; public class Calculator extends JFrame implements ActionListener { private JTextField textField; private JButton btn1, btn2, btn3, btn4, btn5, btn6, btn7, btn8, btn9, btn0; private JButton btnAdd, btnSub, btnMul, btnDiv, btnSqrt, btnPercent, btnClear, btnDelete, btnEqual; private double num1 = 0, num2 = 0, result = 0; private String operator = ""; public Calculator() { // 设置窗体的标题和大小 setTitle("模拟计算器-江海大"); setSize(350, 400); setLocationRelativeTo(null); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); // 创建一个面板，用于放置文本框和按钮 JPanel panel = new JPanel(); panel.setLayout(null); // 创建文本框 textField = new JTextField(); textField.setBounds(10, 10, 320, 50); textField.setFont(new Font("Arial", Font.PLAIN, 24)); textField.setEditable(false); panel.add(textField); // 创建数字按钮 btn1 = new JButton("1"); btn1.setBounds(10, 80, 60, 60); btn1.setFont(new Font("Arial", Font.PLAIN, 24)); btn1.addActionListener(this); panel.add(btn1); btn2 = new JButton("2"); btn2.setBounds(80, 80, 60, 60); btn2.setFont(new Font("Arial", Font.PLAIN, 24)); btn2.addActionListener(this); panel.add(btn2); btn3 = new JButton("3"); btn3.setBounds(150, 80, 60, 60); btn3.setFont(new Font("Arial", Font.PLAIN, 24)); btn3.addActionListener(this); panel.add(btn3); btn4 = new JButton("4"); btn4.setBounds(10, 150, 60, 60); btn4.setFont(new Font("Arial", Font.PLAIN, 24)); btn4.addActionListener(this); panel.add(btn4); btn5 = new JButton("5"); btn5.setBounds(80, 150, 60, 60); btn5.setFont(new Font("Arial", Font.PLAIN, 24)); btn5.addActionListener(this); panel.add(btn5); btn6 = new JButton("6"); btn6.setBounds(150, 150, 60, 60); btn6.setFont(new Font("Arial", Font.PLAIN, 24)); btn6.addActionListener(this); panel.add(btn6); btn7 = new JButton("7"); btn7.setBounds(10, 220, 60, 60); btn7.setFont(new Font("Arial", Font.PLAIN, 24)); btn7.addActionListener(this); panel.add(btn7); btn8 = new JButton("8"); btn8.setBounds(80, 220, 60, 60); btn8.setFont(new Font("Arial", Font.PLAIN, 24)); btn8.addActionListener(this); panel.add(btn8); btn9 = new JButton("9"); btn9.setBounds(150, 220, 60, 60); btn9.setFont(new Font("Arial", Font.PLAIN, 24)); btn9.addActionListener(this); panel.add(btn9); btn0 = new JButton("0"); btn0.setBounds(80, 290, 60, 60); btn0.setFont(new Font("Arial", Font.PLAIN, 24)); btn0.addActionListener(this); panel.add(btn0); // 创建运算符按钮 btnAdd = new JButton("+"); btnAdd.setBounds(220, 80, 60, 60); btnAdd.setFont(new Font("Arial", Font.PLAIN, 24)); btnAdd.addActionListener(this); panel.add(btnAdd); btnSub = new JButton("-"); btnSub.setBounds(290, 80, 60, 60); btnSub.setFont(new Font("Arial", Font.PLAIN, 24)); btnSub.addActionListener(this); panel.add(btnSub); btnMul = new JButton("×"); btnMul.setBounds(220, 150, 60, 60); btnMul.setFont(new Font("Arial", Font.PLAIN, 24)); btnMul.addActionListener(this); panel.add(btnMul); btnDiv = new JButton("÷"); btnDiv.setBounds(290, 150, 60, 60); btnDiv.setFont(new Font("Arial", Font.PLAIN, 24)); btnDiv.addActionListener(this); panel.add(btnDiv); btnSqrt = new JButton("√"); btnSqrt.setBounds(220, 220, 60, 60); btnSqrt.setFont(new Font("Arial", Font.PLAIN, 24)); btnSqrt.addActionListener(this); panel.add(btnSqrt); btnPercent = new JButton("%"); btnPercent.setBounds(290, 220, 60, 60); btnPercent.setFont(new Font("Arial", Font.PLAIN, 24)); btnPercent.addActionListener(this); panel.add(btnPercent); btnClear = new JButton("C"); btnClear.setBounds(220, 290, 60, 60); btnClear.setFont(new Font("Arial", Font.PLAIN, 24)); btnClear.addActionListener(this); panel.add(btnClear); btnDelete = new JButton("←"); btnDelete.setBounds(290, 290, 60, 60); btnDelete.setFont(new Font("Arial", Font.PLAIN, 24)); btnDelete.addActionListener(this); panel.add(btnDelete); btnEqual = new JButton("="); btnEqual.setBounds(220, 10, 130, 50); btnEqual.setFont(new Font("Arial", Font.PLAIN, 24)); btnEqual.addActionListener(this); panel.add(btnEqual); // 将面板添加到窗体中 add(panel); // 显示窗体 setVisible(true); } @Override public void actionPerformed(ActionEvent e) { String command = e.getActionCommand(); switch (command) { case "0": case "1": case "2": case "3": case "4": case "5": case "6": case "7": case "8": case "9": // 数字按键 textField.setText(textField.getText() + command); break; case "+": case "-": case "×": case "÷": // 双目运算符按键 num1 = Double.parseDouble(textField.getText()); operator = command; textField.setText(""); break; case "√": case "%": // 单目运算符按键 num1 = Double.parseDouble(textField.getText()); operator = command; calculate(); break; case "C": // 清空按键 num1 = 0; num2 = 0; operator = ""; result = 0; textField.setText(""); break; case "←": // 退格按键 String text = textField.getText(); if (text.length() > 0) { textField.setText(text.substring(0, text.length() - 1)); } break; case "=": // 等号按键 num2 = Double.parseDouble(textField.getText()); calculate(); break; } } private void calculate() { switch (operator) { case "+": result = num1 + num2; break; case "-": result = num1 - num2; break; case "×": result = num1 * num2; break; case "÷": result = num1 / num2; break; case "√": result = Math.sqrt(num1); break; case "%": result = num1 / 100; break; } textField.setText(String.valueOf(result)); } public static void main(String[] args) { new Calculator(); } } ``` 运行程序后，可以看到一个简易计算器的界面，如下图所示：  可以通过点击不同的按钮，输入数字和运算符，进行计算。