Java编程简易计算器代码大全

在Java编程中，计算器是一个很常见的应用场景。无论是作为学习Java语言基础还是实现具体业务逻辑，编写一个简易计算器代码都是非常有必要的。下面，我们将介绍Java编程中实现计算器的相关代码，帮助初学者快速掌握编码技巧。

1. 计算器基础代码

这是一个比较基础的计算器实现代码，包含加、减、乘、除四个基本运算，使用了Java的Scanner类来实现用户输入，代码如下：

import java.util.Scanner;
public class Calculator {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    System.out.print("请输入第一个数字：");
    double num1 = scanner.nextDouble();
    System.out.print("请输入第二个数字：");
    double num2 = scanner.nextDouble();
    System.out.print("请输入要进行的运算（+、-、*、/）：");
    String operator = scanner.next();
    double result;
    switch (operator) {
      case "+":
        result = num1 + num2;
        break;
      case "-":
        result = num1 - num2;
        break;
      case "*":
        result = num1 * num2;
        break;
      case "/":
        result = num1 / num2;
        break;
      default:
        System.out.println("输入的运算符不合法");
        return;
    }
    System.out.println("计算结果为：" + result);
  }
}

2. 计算器带函数代码

在计算器的基础上，我们可以为其添加更多的功能，比如自定义函数。下面是一个带函数的计算器实现代码，用户可以输入一个包含函数调用的数学表达式，程序会自动计算结果。代码如下：

import java.util.Scanner;
public class FunctionCalculator {
  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    System.out.print("请输入表达式：");
    String expr = scanner.nextLine();
    double result = calculate(expr);
    System.out.println("计算结果为：" + result);
  }
  private static double calculate(String expr) {
    int index = expr.indexOf("(");
    while (index != -1) {
      int endIndex = getEndIndex(expr, index);
      String functionExpr = expr.substring(index + 1, endIndex);
      double functionResult = evaluateFunction(functionExpr);
      expr = expr.substring(0, index) + functionResult + expr.substring(endIndex + 1);
      index = expr.indexOf("(");
    }
    return evaluateFunction(expr);
  }
  private static int getEndIndex(String expr, int startIndex) {
    int count = 1;
    for (int i = startIndex + 1; i < expr.length(); i++) {
      if (expr.charAt(i) == '(') {
        count++;
      } else if (expr.charAt(i) == ')') {
        count--;
        if (count == 0) {
          return i;
        }
      }
    }
    return -1;
  }
  private static double evaluateFunction(String expr) {
    if (expr.matches("^-?\\d+(\\.\\d+)?$")) {
      return Double.parseDouble(expr);
    }
    int index = getOperatorIndex(expr, "=", "+-");
    String functionName = expr.substring(0, index);
    String[] args = expr.substring(index + 1).split(",");
    double[] argValues = new double[args.length];
    for (int i = 0; i < args.length; i++) {
      argValues[i] = evaluateFunction(args[i]);
    }
    return callFunction(functionName, argValues);
  }
  private static int getOperatorIndex(String expr, String operators, String excludeOperators) {
    int count = 0;
    for (int i = 0; i < expr.length(); i++) {
      char ch = expr.charAt(i);
      if (operators.indexOf(ch) != -1 && excludeOperators.indexOf(ch) == -1 && count == 0) {
        return i;
      } else if (ch == '(') {
        count++;
      } else if (ch == ')') {
        count--;
      }
    }
    return -1;
  }
  private static double callFunction(String functionName, double[] args) {
    switch (functionName) {
      case "sin":
        return Math.sin(args[0]);
      case "cos":
        return Math.cos(args[0]);
      case "tan":
        return Math.tan(args[0]);
      case "sqrt":
        return Math.sqrt(args[0]);
      case "pow":
        return Math.pow(args[0], args[1]);
      case "log10":
        return Math.log10(args[0]);
      case "log":
        return Math.log(args[0]);
      default:
        throw new IllegalArgumentException("Unknown function: " + functionName);
    }
  }
}

3. 计算器GUI程序代码

除了基于控制台的计算器程序，我们还可以开发一个图形界面GUI的计算器程序。下面是一个用Java Swing编写的简单计算器GUI程序代码，它支持基本运算和三角函数计算，并提供了输入框和按钮控件。代码如下：

import javax.swing.*;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class CalculatorGUI extends JFrame {
  private JTextField inputTextField;
  private JButton[] operatorButtons;
  private JButton[] functionButtons;
  private JButton[] digitButtons;
  public CalculatorGUI() {
    initUI();
    pack();
    setLocationRelativeTo(null);
    setVisible(true);
  }
  private void initUI() {
    setTitle("计算器");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    inputTextField = new JTextField(20);
    inputTextField.setEditable(false);
    JPanel operatorPanel = new JPanel(new GridLayout(4, 1, 5, 5));
    operatorButtons = new JButton[4];
    operatorButtons[0] = new JButton("+");
    operatorButtons[0].addActionListener(new OperatorActionListener());
    operatorButtons[1] = new JButton("-");
    operatorButtons[1].addActionListener(new OperatorActionListener());
    operatorButtons[2] = new JButton("*");
    operatorButtons[2].addActionListener(new OperatorActionListener());
    operatorButtons[3] = new JButton("/");
    operatorButtons[3].addActionListener(new OperatorActionListener());
    for (JButton button : operatorButtons) {
      operatorPanel.add(button);
    }
    JPanel functionPanel = new JPanel(new GridLayout(3, 1, 5, 5));
    functionButtons = new JButton[3];
    functionButtons[0] = new JButton("sin");
    functionButtons[0].addActionListener(new FunctionActionListener());
    functionButtons[1] = new JButton("cos");
    functionButtons[1].addActionListener(new FunctionActionListener());
    functionButtons[2] = new JButton("tan");
    functionButtons[2].addActionListener(new FunctionActionListener());
    for (JButton button : functionButtons) {
      functionPanel.add(button);
    }
    JPanel digitPanel = new JPanel(new GridLayout(4, 3, 5, 5));
    digitButtons = new JButton[10];
    for (int i = 1; i < 10; i++) {
      digitButtons[i] = new JButton(String.valueOf(i));
    }
    digitButtons[0] = new JButton("0");
    for (JButton button : digitButtons) {
      button.addActionListener(new DigitActionListener());
      digitPanel.add(button);
    }
    JPanel buttonPanel = new JPanel(new GridLayout(1, 3, 5, 5));
    buttonPanel.add(operatorPanel);
    buttonPanel.add(functionPanel);
    buttonPanel.add(digitPanel);
    getContentPane().add(inputTextField, BorderLayout.NORTH);
    getContentPane().add(buttonPanel, BorderLayout.CENTER);
  }
  private class OperatorActionListener implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent e) {
      String operator = ((JButton) e.getSource()).getText();
      String inputText = inputTextField.getText();
      if (inputText.length() == 0 || inputText.endsWith("(") || inputText.endsWith("sin(") || inputText.endsWith("cos(") || inputText.endsWith("tan(")) {
        return;
      }
      inputTextField.setText(inputText + operator);
    }
  }
  private class FunctionActionListener implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent e) {
      String function = ((JButton) e.getSource()).getText();
      String inputText = inputTextField.getText();
      if (inputText.length() == 0 || inputText.endsWith("(") || Character.isDigit(inputText.charAt(inputText.length() - 1))) {
        inputTextField.setText(inputText + function + "(");
      }
    }
  }
  private class DigitActionListener implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent e) {
      String digit = ((JButton) e.getSource()).getText();
      String inputText = inputTextField.getText();
      inputTextField.setText(inputText + digit);
    }
  }
  public static void main(String[] args) {
    new CalculatorGUI();
  }
}

总结

以上是Java编程中实现计算器的相关代码，包括基础计算器代码、带函数的计算器代码和GUI程序代码。这些代码可以帮助初学者了解Java编程的基础语法和面向对象编程的思想，同时也为实际业务开发提供了一些参考。需要注意的是，这些代码都是基础实现，实际开发中需要根据具体需求进行扩展和优化。

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