用Java Swing编写一个简单的计算器界面 |21xrx.com

用Java Swing编写一个简单的计算器界面

2023-06-11 10:41:23 深夜i -- --

Java Swing

我最近学习了Java的Swing库，这个库可以方便地编写GUI界面，于是我想写一个计算器界面来练手。下面是我的代码：


import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Calculator extends JFrame implements ActionListener {
  private JTextField display;
  private double operand1, operand2;
  private String operator;
  private boolean waitingForOperand2;
  public Calculator() {
    super("Calculator");
    operand1 = 0;
    operand2 = 0;
    waitingForOperand2 = false;
    JPanel buttonPanel = new JPanel();
    buttonPanel.setLayout(new GridLayout(4, 4));
    String[] buttonLabels = {"7", "8", "9", "/", "4", "5", "6", "*", "1", "2", "3", "-", "0", ".", "=", "+"};
    for (String label : buttonLabels) {
      JButton button = new JButton(label);
      button.addActionListener(this);
      buttonPanel.add(button);
    }
    display = new JTextField();
    display.setEditable(false);
    Container container = getContentPane();
    container.add(display, BorderLayout.NORTH);
    container.add(buttonPanel, BorderLayout.CENTER);
    setSize(300, 300);
    setVisible(true);
  }
  public static void main(String[] args) {
    Calculator calculator = new Calculator();
    calculator.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  }
  public void actionPerformed(ActionEvent event) {
    String label = event.getActionCommand();
    if (label.equals("C")) {
      operand1 = 0;
      operand2 = 0;
      operator = null;
      waitingForOperand2 = false;
      display.setText("");
    } else if ("0123456789.".indexOf(label) >= 0) {
      if (waitingForOperand2) {
        display.setText("");
        waitingForOperand2 = false;
      }
      display.setText(display.getText() + label);
    } else {
      if (!waitingForOperand2) {
        waitingForOperand2 = true;
        operand1 = Double.parseDouble(display.getText());
        operator = label;
      } else {
        operand2 = Double.parseDouble(display.getText());
        double result = evaluate();
        display.setText(Double.toString(result));
        operand1 = result;
        operator = label;
      }
    }
  }
  private double evaluate() {
    if (operator.equals("+")) {
      return operand1 + operand2;
    } else if (operator.equals("-"))
      return operand1 - operand2;
     else if (operator.equals("*")) {
      return operand1 * operand2;
    } else if (operator.equals("/"))
      return operand1 / operand2;
     else
      return 0;
    
  }
}

这个计算器界面比较简单，只支持四则运算和小数点。我使用了GridLayout布局，将16个按钮放在了一个4x4的矩阵中。点击按钮时，我使用了ActionListener来处理事件。我使用了一个字符串变量operator来存储运算符，一个布尔变量waitingForOperand2来标记是否正在等待输入第二个操作数，以及两个双精度浮点数变量operand1和operand2来存储操作数。

三个，GUI，计算器。

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