jsq/jsq6267/CalculatorApp.java

package jsq6267;

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.TextField;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;

public class CalculatorApp extends Application {

    private TextField display;
    private double firstNumber = 0;
    private boolean userIsTypingSecondNumber = false;
    private String currentOperator = "";

    @Override
    public void start(Stage primaryStage) {
        primaryStage.setTitle("计算器");

        display = new TextField();
        display.setEditable(false);
        display.setPrefColumnCount(16);

        GridPane grid = new GridPane();
        grid.setAlignment(Pos.CENTER);
        grid.setPadding(new Insets(10, 10, 10, 10));
        grid.setVgap(8);
        grid.setHgap(8);

        // 添加数字按钮
        for (int i = 1; i <= 9; i++) {
            Button btn = new Button(String.valueOf(i));
            int finalI = i; // 使用 finalI 来捕获 i 的值
            btn.setOnAction(e -> appendNumber(finalI));
            grid.add(btn, (i - 1) % 3, (i - 1) / 3 + 1);
        }

        // 添加0按钮
        Button btn0 = new Button("0");
        btn0.setOnAction(e -> appendNumber(0));
        grid.add(btn0, 0, 4, 2, 1); // 占据两列

        // 添加点按钮
        Button btnDot = new Button(".");
        btnDot.setOnAction(e -> appendDot());
        grid.add(btnDot, 2, 4);

        // 添加操作符按钮
        String[] operators = {"+", "-", "*", "/"};
        for (int i = 0; i < operators.length; i++) {
            Button btnOp = new Button(operators[i]);
            String finalOp = operators[i]; // 使用 finalOp 来捕获 operators[i] 的值
            btnOp.setOnAction(e -> setOperator(finalOp));
            grid.add(btnOp, 3, i + 1);
        }

        // 添加等号按钮
        Button btnEquals = new Button("=");
        btnEquals.setOnAction(e -> calculate());
        grid.add(btnEquals, 1, 5, 2, 1); // 占据两列

        // 添加清除按钮
        Button btnClear = new Button("C");
        btnClear.setOnAction(e -> clear());
        grid.add(btnClear, 3, 5);

        // 将显示框添加到网格的第一行
        grid.add(display, 0, 0, 4, 1);

        Scene scene = new Scene(grid, 300, 400);

        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private void appendNumber(int number) {
        if (userIsTypingSecondNumber) {
            display.setText(display.getText() + number);
        } else {
            firstNumber = firstNumber * 10 + number;
            display.setText(String.valueOf(firstNumber));
        }
    }

    private void appendDot() {
        if (!display.getText().contains(".")) {
            display.setText(display.getText() + ".");
        }
    }

    private void setOperator(String operator) {
        if (!currentOperator.isEmpty()) {
            calculate();
        }
        currentOperator = operator;
        userIsTypingSecondNumber = true;
        display.setText("");
    }

    private void calculate() {
        double secondNumber = Double.parseDouble(display.getText());
        double result = 0;
        boolean valid = true;

        switch (currentOperator) {
            case "+":
                result = firstNumber + secondNumber;
                break;
            case "-":
                result = firstNumber - secondNumber;
                break;
            case "*":
                result = firstNumber * secondNumber;
                break;
            case "/":
                if (secondNumber == 0) {
                    display.setText("错误");
                    valid = false;
                } else {
                    result = firstNumber / secondNumber;
                }
                break;
        }

        if (valid) {
            display.setText(String.valueOf(result));
            firstNumber = result;
            currentOperator = "";
            userIsTypingSecondNumber = false;
        }
    }

    private void clear() {
        display.setText("");
        firstNumber = 0;
        userIsTypingSecondNumber = false;
        currentOperator = "";
    }

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