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Java编程实现图形界面计算器并记录历史记录
2023-06-15 15:21:35 深夜i     --     --
Java编程 图形界面程序 计算器 历史记录 集合框架 文件读写

在日常生活中，计算器是我们常用的一个工具，而计算器程序的开发也是Java编程中很基础的内容之一。本文将介绍如何使用Java编写一款图形界面的计算器程序，并记录计算历史记录。

1. 实现基本的计算器功能

首先，我们需要实现基本的计算器功能，包括数字按钮、运算符按钮、等号按钮、清空按钮等。我们可以使用JavaFX来实现图形界面，下面是示例代码：



import javafx.application.Application;


import javafx.geometry.Insets;


import javafx.geometry.Pos;


import javafx.scene.Scene;


import javafx.scene.control.Button;


import javafx.scene.control.Label;


import javafx.scene.control.TextField;


import javafx.scene.layout.GridPane;


import javafx.scene.layout.HBox;


import javafx.stage.Stage;


public class Calculator extends Application {


  private TextField txtResult;


  private String operator = "";


  private double firstNumber = 0;


  private double secondNumber = 0;


  @Override


  public void start(Stage primaryStage) {


    txtResult = new TextField();


    txtResult.setEditable(false);


    txtResult.setAlignment(Pos.CENTER_RIGHT);


    Button btn0 = new Button("0");


    btn0.setOnAction(e -> handleNumberButton(e));


    Button btn1 = new Button("1");


    btn1.setOnAction(e -> handleNumberButton(e));


    Button btn2 = new Button("2");


    btn2.setOnAction(e -> handleNumberButton(e));


    Button btn3 = new Button("3");


    btn3.setOnAction(e -> handleNumberButton(e));


    Button btn4 = new Button("4");


    btn4.setOnAction(e -> handleNumberButton(e));


    Button btn5 = new Button("5");


    btn5.setOnAction(e -> handleNumberButton(e));


    Button btn6 = new Button("6");


    btn6.setOnAction(e -> handleNumberButton(e));


    Button btn7 = new Button("7");


    btn7.setOnAction(e -> handleNumberButton(e));


    Button btn8 = new Button("8");


    btn8.setOnAction(e -> handleNumberButton(e));


    Button btn9 = new Button("9");


    btn9.setOnAction(e -> handleNumberButton(e));


    Button btnPlus = new Button("+");


    btnPlus.setOnAction(e -> handleOperatorButton(e));


    Button btnMinus = new Button("-");


    btnMinus.setOnAction(e -> handleOperatorButton(e));


    Button btnMultiply = new Button("*");


    btnMultiply.setOnAction(e -> handleOperatorButton(e));


    Button btnDivide = new Button("/");


    btnDivide.setOnAction(e -> handleOperatorButton(e));


    Button btnEqual = new Button("=");


    btnEqual.setOnAction(e -> handleEqualButton(e));


    Button btnClear = new Button("AC");


    btnClear.setOnAction(e -> handleClearButton(e));


    HBox hbox1 = new HBox();


    hbox1.getChildren().addAll(btn7, btn8, btn9, btnPlus);


    hbox1.setSpacing(10);


    hbox1.setPadding(new Insets(10, 10, 10, 10));


    HBox hbox2 = new HBox();


    hbox2.getChildren().addAll(btn4, btn5, btn6, btnMinus);


    hbox2.setSpacing(10);


    hbox2.setPadding(new Insets(10, 10, 10, 10));


    HBox hbox3 = new HBox();


    hbox3.getChildren().addAll(btn1, btn2, btn3, btnMultiply);


    hbox3.setSpacing(10);


    hbox3.setPadding(new Insets(10, 10, 10, 10));


    HBox hbox4 = new HBox();


    hbox4.getChildren().addAll(btn0, btnEqual, btnClear, btnDivide);


    hbox4.setSpacing(10);


    hbox4.setPadding(new Insets(10, 10, 10, 10));


    GridPane pane = new GridPane();


    pane.setAlignment(Pos.CENTER);


    pane.add(txtResult, 0, 0, 4, 1);


    pane.add(hbox1, 0, 1);


    pane.add(hbox2, 0, 2);


    pane.add(hbox3, 0, 3);


    pane.add(hbox4, 0, 4);


    Scene scene = new Scene(pane, 300, 300);


    primaryStage.setScene(scene);


    primaryStage.show();


  }


  private void handleNumberButton(ActionEvent e) {


    Button btn = (Button) e.getSource();


    String number = btn.getText();


    txtResult.setText(txtResult.getText() + number);


  }


  private void handleOperatorButton(ActionEvent e) {


    Button btn = (Button) e.getSource();


    operator = btn.getText();


    firstNumber = Double.parseDouble(txtResult.getText());


    txtResult.setText("");


  }


  private void handleEqualButton(ActionEvent e) {


    if (!txtResult.getText().equals("")) {


      secondNumber = Double.parseDouble(txtResult.getText());


      double result = 0;


      switch (operator) {


        case "+":


          result = firstNumber + secondNumber;


          break;


        case "-":


          result = firstNumber - secondNumber;


          break;


        case "*":


          result = firstNumber * secondNumber;


          break;


        case "/":


          result = firstNumber / secondNumber;


          break;


      }


      txtResult.setText(String.valueOf(result));


    }


  }


  private void handleClearButton(ActionEvent e) {


    operator = "";


    firstNumber = 0;


    secondNumber = 0;


    txtResult.setText("");


  }


}

2. 记录计算历史记录

我们要在计算器程序中加入记录历史记录的功能，可以使用Java的集合框架来实现。我们定义一个List集合来存储计算记录，每次进行一次运算后，将运算表达式以及对应的结果加入到List中，最终将List保存到文件中，下次打开计算器程序时可以将历史记录文件读取到List中显示出来。下面是示例代码：



import javafx.scene.control.Alert;


import javafx.scene.control.Alert.AlertType;


import java.io.*;


import java.util.ArrayList;


import java.util.List;


public class Calculator {


  // 省略上述代码


  private List
  historyList = new ArrayList<>();
 


  private void handleEqualButton(ActionEvent e) {


    if (!txtResult.getText().equals("")) {


      secondNumber = Double.parseDouble(txtResult.getText());


      double result = 0;


      switch (operator) {


        case "+":


          result = firstNumber + secondNumber;


          historyList.add(firstNumber + " + " + secondNumber + " = " + result);


          break;


        case "-":


          result = firstNumber - secondNumber;


          historyList.add(firstNumber + " - " + secondNumber + " = " + result);


          break;


        case "*":


          result = firstNumber * secondNumber;


          historyList.add(firstNumber + " * " + secondNumber + " = " + result);


          break;


        case "/":


          result = firstNumber / secondNumber;


          historyList.add(firstNumber + " / " + secondNumber + " = " + result);


          break;


      }


      txtResult.setText(String.valueOf(result));


      saveHistoryList();


    }


  }


  private void saveHistoryList() {


    try {


      BufferedWriter writer = new BufferedWriter(new FileWriter("history.txt"));


      for (String s : historyList) {


        writer.write(s);


        writer.newLine();


      }


      writer.close();


    } catch (IOException e) {


      Alert alert = new Alert(AlertType.WARNING);


      alert.setTitle("警告");


      alert.setHeaderText("文件写入失败");


      alert.showAndWait();


    }


  }


  private List
  loadHistoryList() {
 


    List
  list = new ArrayList<>();
 


    try {


      BufferedReader reader = new BufferedReader(new FileReader("history.txt"));


      String line;


      while ((line = reader.readLine()) != null) {


        list.add(line);


      }


      reader.close();


    } catch (IOException e) {


      Alert alert = new Alert(AlertType.WARNING);


      alert.setTitle("警告");


      alert.setHeaderText("文件读取失败");


      alert.showAndWait();


    }


    return list;


  }


}

3. 关键词

Java编程、图形界面程序、计算器、历史记录、集合框架、文件读写

  
  

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