利用java实现计算器

好的，实现计算器一般可以分为以下几个步骤：

1. 设计UI界面，包括数字键、操作符键、文本框等组件。
2. 实现数字键和操作符键的响应事件，通过按钮的监听器来实现。
3. 实现计算逻辑，根据用户输入的数字和操作符进行计算，并将结果显示在文本框中。

下面是一个简单的示例代码：

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

public class Calculator extends JFrame implements ActionListener {
    private JTextField textField;
    private JButton buttonAdd, buttonSub, buttonMul, buttonDiv, buttonEqual;
    private JButton button0, button1, button2, button3, button4, button5, button6, button7, button8, button9;
    private double num1, num2;
    private String operator, input;

    public Calculator() {
        setTitle("Calculator");
        setLayout(new BorderLayout());

        textField = new JTextField();
        textField.setEditable(false);
        add(textField, BorderLayout.NORTH);

        JPanel buttonPanel = new JPanel(new GridLayout(4, 4));

        button1 = new JButton("1");
        button1.addActionListener(this);
        buttonPanel.add(button1);

        button2 = new JButton("2");
        button2.addActionListener(this);
        buttonPanel.add(button2);

        button3 = new JButton("3");
        button3.addActionListener(this);
        buttonPanel.add(button3);

        buttonAdd = new JButton("+");
        buttonAdd.addActionListener(this);
        buttonPanel.add(buttonAdd);

        button4 = new JButton("4");
        button4.addActionListener(this);
        buttonPanel.add(button4);

        button5 = new JButton("5");
        button5.addActionListener(this);
        buttonPanel.add(button5);

        button6 = new JButton("6");
        button6.addActionListener(this);
        buttonPanel.add(button6);

        buttonSub = new JButton("-");
        buttonSub.addActionListener(this);
        buttonPanel.add(buttonSub);

        button7 = new JButton("7");
        button7.addActionListener(this);
        buttonPanel.add(button7);

        button8 = new JButton("8");
        button8.addActionListener(this);
        buttonPanel.add(button8);

        button9 = new JButton("9");
        button9.addActionListener(this);
        buttonPanel.add(button9);

        buttonMul = new JButton("*");
        buttonMul.addActionListener(this);
        buttonPanel.add(buttonMul);

        button0 = new JButton("0");
        button0.addActionListener(this);
        buttonPanel.add(button0);

        buttonEqual = new JButton("=");
        buttonEqual.addActionListener(this);
        buttonPanel.add(buttonEqual);

        buttonDiv = new JButton("/");
        buttonDiv.addActionListener(this);
        buttonPanel.add(buttonDiv);

        add(buttonPanel, BorderLayout.CENTER);

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(300, 300);
        setVisible(true);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == button0) {
            input += "0";
            textField.setText(input);
        } else if (e.getSource() == button1) {
            input += "1";
            textField.setText(input);
        } else if (e.getSource() == button2) {
            input += "2";
            textField.setText(input);
        } else if (e.getSource() == button3) {
            input += "3";
            textField.setText(input);
        } else if (e.getSource() == button4) {
            input += "4";
            textField.setText(input);
        } else if (e.getSource() == button5) {
            input += "5";
            textField.setText(input);
        } else if (e.getSource() == button6) {
            input += "6";
            textField.setText(input);
        } else if (e.getSource() == button7) {
            input += "7";
            textField.setText(input);
        } else if (e.getSource() == button8) {
            input += "8";
            textField.setText(input);
        } else if (e.getSource() == button9) {
            input += "9";
            textField.setText(input);
        } else if (e.getSource() == buttonAdd) {
            num1 = Double.parseDouble(input);
            operator = "+";
            input = "";
        } else if (e.getSource() == buttonSub) {
            num1 = Double.parseDouble(input);
            operator = "-";
            input = "";
        } else if (e.getSource() == buttonMul) {
            num1 = Double.parseDouble(input);
            operator = "*";
            input = "";
        } else if (e.getSource() == buttonDiv) {
            num1 = Double.parseDouble(input);
            operator = "/";
            input = "";
        } else if (e.getSource() == buttonEqual) {
            num2 = Double.parseDouble(input);
            double result = 0;
            switch (operator) {
                case "+":
                    result = num1 + num2;
                    break;
                case "-":
                    result = num1 - num2;
                    break;
                case "*":
                    result = num1 * num2;
                    break;
                case "/":
                    result = num1 / num2;
                    break;
            }
            textField.setText("" + result);
            input = "";
        }
    }

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

这是一个简单的计算器，您可以根据自己的需求进行修改和完善。