Java实现简易计算器 - 完整代码及案例分析 |21xrx.com

Java实现简易计算器 - 完整代码及案例分析

2023-06-16 18:28:11 深夜i -- --

Java 计算器 GUI 逻辑完整代码

计算器一直是程序开发中的一个经典案例，无论是初学者还是资深程序员都能从中受益。本文将介绍如何使用Java编写一个简易计算器，并提供完整的代码和实际演示案例。

1. 编写计算器界面

首先，我们需要为计算器创建一个用户界面。使用Java Swing提供的GUI组件库，我们可以轻松地创建一个支持标准算术操作的简单计算器。以下是一个基本的计算器GUI示例：


import javax.swing.*;
import java.awt.*;
public class CalculatorGUI {
  public static void main(String[] args) {
    JFrame frame = new JFrame("简易计算器");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(300, 400);
    JPanel panel1 = new JPanel();
    JPanel panel2 = new JPanel();
    panel1.setLayout(new GridLayout(4, 3));
    panel2.setLayout(new GridLayout(5,1));
    
    JTextField textField = new JTextField("0");
    textField.setEditable(false);
    JButton button0 = new JButton("0");
    JButton button1 = new JButton("1");
    JButton button2 = new JButton("2");
    JButton button3 = new JButton("3");
    JButton button4 = new JButton("4");
    JButton button5 = new JButton("5");
    JButton button6 = new JButton("6");
    JButton button7 = new JButton("7");
    JButton button8 = new JButton("8");
    JButton button9 = new JButton("9");
    JButton buttonC = new JButton("C");
    JButton buttonPlus = new JButton("+");
    JButton buttonMinus = new JButton("-");
    JButton buttonMultiply = new JButton("x");
    JButton buttonDivide = new JButton("/");
    JButton buttonEquals = new JButton("=");
    
    panel1.add(button1);
    panel1.add(button2);
    panel1.add(button3);
    panel1.add(button4);
    panel1.add(button5);
    panel1.add(button6);
    panel1.add(button7);
    panel1.add(button8);
    panel1.add(button9);
    panel1.add(buttonC);
    panel1.add(button0);
    panel1.add(buttonEquals);
    
    panel2.add(buttonPlus);
    panel2.add(buttonMinus);
    panel2.add(buttonMultiply);
    panel2.add(buttonDivide);
    panel2.add(textField);
    
    frame.getContentPane().add(BorderLayout.CENTER, panel1);
    frame.getContentPane().add(BorderLayout.EAST, panel2);
    frame.setVisible(true);
  }
}

2. 实现计算器逻辑

下一步是实现计算器的逻辑。我们需要在用户按下数字和操作符按钮时执行相应的计算，并在文本框中显示结果。以下是一种实现方法：


public class CalculatorLogic {
  private double currentResult;
  private String currentOperator;
  private boolean operationStarted;
  
  public CalculatorLogic()
    currentResult = 0;
    currentOperator = "";
    operationStarted = false;
  
  
  public void enterDigit(int digit) {
    if(operationStarted) {
      currentResult = Double.parseDouble(JTextField.getText());
      operationStarted = false;
    }
    else {
      currentResult *= 10;
    }
    currentResult += digit;
    updateDisplay();
  }
  
  public void enterOperator(String operator) {
    if(currentOperator.equals("+")) {
      currentResult += Double.parseDouble(JTextField.getText());
    }
    else if(currentOperator.equals("-")) {
      currentResult -= Double.parseDouble(JTextField.getText());
    }
    else if(currentOperator.equals("x")) {
      currentResult *= Double.parseDouble(JTextField.getText());
    }
    else if(currentOperator.equals("/")) {
      currentResult /= Double.parseDouble(JTextField.getText());
    }
    else {
      currentResult = Double.parseDouble(JTextField.getText());
    }
    currentOperator = operator;
    operationStarted = true;
  }
  
  private void updateDisplay() {
    JTextField.setText(Double.toString(currentResult));
  }
}

3. 组合GUI和逻辑

最后，我们需要将计算器GUI和逻辑组合在一起。我们可以将计算器逻辑作为一个单独的类，并在GUI中创建一个实例。然后，我们可以将按钮的动作侦听器分配给适当的方法，例如：


public class CalculatorGUI {
  private CalculatorLogic logic;
  private JTextField textField;
  private JButton button0;
  private JButton button1;
  // ...
  public CalculatorGUI() {
    JFrame frame = new JFrame("简易计算器");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(300, 400);
    JPanel panel1 = new JPanel();
    JPanel panel2 = new JPanel();
    panel1.setLayout(new GridLayout(4, 3));
    panel2.setLayout(new GridLayout(5,1));
    
    textField = new JTextField("0");
    textField.setEditable(false);
    button0 = new JButton("0");
    button1 = new JButton("1");
    // ...
    
    logic = new CalculatorLogic();
    
    button0.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent event) {
        logic.enterDigit(0);
      }
    });
    button1.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent event) {
        logic.enterDigit(1);
      }
    });
    // ...
    
    panel1.add(button1);
    panel1.add(button2);
    // ...
    panel2.add(buttonPlus);
    panel2.add(buttonMinus);
    // ...
    panel2.add(textField);
    
    frame.getContentPane().add(BorderLayout.CENTER, panel1);
    frame.getContentPane().add(BorderLayout.EAST, panel2);
    frame.setVisible(true);
  }
}

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