小贝子编程

JavaFX 计算器中的方程式问题



我的JavaFX/Java计算器有问题。当我输入一个方程式时，它(计算器(工作正常，答案也是正确的。但是当我按下/键入另一个操作和之后的另一个数字时，结果/总和/等将不正确，除非我按下/键入的运算符与以前相同。下面是一个示例：

作品： 2 + 6 = 8 + 2 = 10

不起作用：2 + 6 = 8 - 2 = 10

作品： 6 x 2 = 12 x 2 = 26

不起作用：6 x 2 = 12 ÷ 2 = 26

我想知道是否有任何方法可以解决这个问题。

这是我的 FXML 控制器类：

package calculator;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.input.KeyCode;
import javafx.stage.Stage;
import java.lang.Math;
public class Calculator implements Initializable {
    double data = 0d;
    int operation = -1;
    private boolean start = false;
    @FXML
    private Label display;
    @FXML
    private Button two;
    @FXML
    private Button five;
    @FXML
    private Button four;
    @FXML
    private Button three;
    @FXML
    private Button one;
    @FXML
    private Button six;
    @FXML
    private Button seven;
    @FXML
    private Button multi;
    @FXML
    private Button add;
    @FXML
    private Button divide;
    @FXML
    private Button minus;
    @FXML
    private Button equals;
    @FXML
    private Button clear;
    @FXML
    private Button zero;
    @FXML
    private Button nine;
    @FXML
    private Button eight;
    @FXML
    void handleButtonAction(ActionEvent event) {
        if(start)
        {
            display.setText("");
            start = false;
        }
        if(event.getSource() == one)
        {
            display.setText(display.getText() + "1");
        }
        else if(event.getSource() == two)
        {
            display.setText(display.getText() + "2");
        }
        else if(event.getSource() == three)
        {
            display.setText(display.getText() + "3");
        }
        else if(event.getSource() == four)
        {
            display.setText(display.getText() + "4");
        }
        else if(event.getSource() == five)
        {
            display.setText(display.getText() + "5");
        }
        else if(event.getSource() == six)
        {
            display.setText(display.getText() + "6");
        }
        else if(event.getSource() == seven)
        {
            display.setText(display.getText() + "7");
        }
        else if(event.getSource() == eight)
        {
            display.setText(display.getText() + "8");
        }
        else if(event.getSource() == nine)
        {
            display.setText(display.getText() + "9");
        }
        else if(event.getSource() == zero)
        {
            display.setText(display.getText() + "0");
        }
        else if(event.getSource() == clear)
        {
            display.setText("");
        } 
        else if(event.getSource() == add)
        {
            data = Float.parseFloat(display.getText());
            operation = 1;
            display.setText("");
        }
        else if(event.getSource() == minus)
        {
            data = Float.parseFloat(display.getText());
            operation = 2;
            display.setText("");
        }
        else if(event.getSource() == multi)
        {
            data = Float.parseFloat(display.getText());
            operation = 3;
            display.setText("");
        }
        else if(event.getSource() == divide)
        {
            data = Float.parseFloat(display.getText());
            operation = 4;
            display.setText("");
        }
        else if(event.getSource() == equals)
        {
            Float secondOperand = Float.parseFloat(display.getText());
            switch(operation)
            {
                case 1: //Addition
                    Double ans = data + secondOperand;
                    display.setText(String.valueOf(ans));
                    //data = ans;
                    break;
                case 2: //Subtraction
                    ans = data - secondOperand;
                    display.setText(String.valueOf(ans));
                    //data = ans;
                    break;
                case 3: //Multiplication
                    ans = data * secondOperand;
                    display.setText(String.valueOf(ans));
                    //data = ans;
                    break;
                case 4: //Division
                    ans = 0d;
                    try{
                    ans = data / secondOperand;
                    }catch(Exception ex){display.setText("Error");}
                    display.setText(String.valueOf(ans));
                    //data = ans;
                    break;
            }
            if(event.getSource() != divide && event.getSource() != add && event.getSource() != multi && event.getSource() != minus)
            {
                start = true;
            }
        }
    }
@FXML
    private void send2sceneconver(ActionEvent event) throws Exception{
        Parent rootBMI = FXMLLoader.load(getClass().getResource("ConversionCal.fxml"));
        Scene scene2 = new Scene(rootBMI);
        Stage calS = (Stage) ((Node) event.getSource()).getScene().getWindow();
        calS.setScene(scene2);
        calS.show();
    }
    @Override
    public void initialize(URL url, ResourceBundle rb) {
        // TODO
    }  
}

任何帮助将不胜感激。

按 equals 按钮执行以下操作

else if(event.getSource() == equals)
{
    ...
    if(event.getSource() != divide && event.getSource() != add && event.getSource() != multi && event.getSource() != minus)
    {
        start = true;
    }
}

由于source是equals的，而不是其他的，因此您始终将start设置为true，在按下下一个按钮时，display的内容替换为空字符串：

if(start)
{
    display.setText("");
    start = false;
}

这会导致下一个调用 to 引发NumberFormatException

data = Float.parseFloat(display.getText());

由于对operation字段的分配发生在此调用之后，因此在按 equals 后立即按运算符按钮不会导致字段值的更新，并且始终保留旧运算符。

相反，您应该做的是引入一个字段，告诉您第一个操作数是否可用或必须解析。

private final Set<Button> numbers = new HashSet<>();
private final Map<Button, Integer> operators = new HashMap<>();
@Override
public void initialize(URL url, ResourceBundle rb) {
    numbers.addAll(Arrays.asList(zero, one, two, three, four, five, six, seven, eight, nine));
    operators.put(add, 1);
    operators.put(minus, 2);
    operators.put(multi, 3);
    operators.put(divide, 4);
}
private double data;
private boolean dataAvailable = false;
@FXML
private void handleButtonAction(ActionEvent event) {
    Button source = (Button) event.getSource();
    if (source == clear) {
        dataAvailable = false;
        display.setText("");
        operation = 0;
    } else if (source == equals) {
        double secondOperand;
        try {
            secondOperand = Double.parseDouble(display.getText());
        } catch (NumberFormatException ex) {
            return; // only continue, if parsing is successful
        }
        double result;
        switch (operation) {
            case 1: //Addition
                result = data + secondOperand;
                break;
            case 2: //Subtraction
                result = data - secondOperand;
                break;
            case 3: //Multiplication
                result = data * secondOperand;
                break;
            case 4: //Division
                double res = data / secondOperand;
                if (Double.isFinite(res)) {
                    result = res;
                } else {
                    // TODO: division by zero
                }
                break;
            default:
                return; // ignore press, if operand is not set yet
        }
        display.setText(Double.toString(result));
        operation = 0;
        data = result;
        dataAvailable = true;
    } else if (numbers.contains(source)) {
        if (!dataAvailable) { // just ignore input, if = gave us the first operand
            display.setText(display.getText() + source.getText());
        }
    } else {
        Integer op = operators.get(source);
        if (op != null) {
            if (!dataAvailable) {
                try {
                    data = Double.parseDouble(display.getText());
                } catch (NumberFormatException ex) {
                    return; // do nothing on invalid input
                }
            } else {
                dataAvailable = false;
            }
            display.setText("");
            operation = op;
        }
    }
}
所以我

不确定为什么它在那里，但问题出在这个 if 语句上

    if(start)
    {
        display.setText("");
        start = false;
    }

我已经用你的作品与不起作用的方程式测试了它，一切似乎都很好。 破坏它的原因是它在执行下一个操作时重置了显示器，因此在观看时看起来不错，但是在尝试执行操作时数据会被清除。所以它没有最后的数据可以提取。 我把它注释掉了，其余的似乎在这里工作是我的课程进行验证

import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.stage.Stage;
import java.net.URL;
import java.util.ResourceBundle;

public class Calculator implements Initializable {
    double data = 0d;
    int operation = -1;
    private boolean start = false;
    @FXML
    private Label display;
    @FXML
    private Button two;
    @FXML
    private Button five;
    @FXML
    private Button four;
    @FXML
    private Button three;
    @FXML
    private Button one;
    @FXML
    private Button six;
    @FXML
    private Button seven;
    @FXML
    private Button multi;
    @FXML
    private Button add;
    @FXML
    private Button divide;
    @FXML
    private Button minus;
    @FXML
    private Button equals;
    @FXML
    private Button clear;
    @FXML
    private Button zero;
    @FXML
    private Button nine;
    @FXML
    private Button eight;
    @FXML
    void handleButtonAction(ActionEvent event) {
//        if(start)
//        {
//            display.setText("");
//            start = false;
//        }
        if(event.getSource() == one)
        {
            display.setText(display.getText() + "1");
        }
        else if(event.getSource() == two)
        {
            display.setText(display.getText() + "2");
        }
        else if(event.getSource() == three)
        {
            display.setText(display.getText() + "3");
        }
        else if(event.getSource() == four)
        {
            display.setText(display.getText() + "4");
        }
        else if(event.getSource() == five)
        {
            display.setText(display.getText() + "5");
        }
        else if(event.getSource() == six)
        {
            display.setText(display.getText() + "6");
        }
        else if(event.getSource() == seven)
        {
            display.setText(display.getText() + "7");
        }
        else if(event.getSource() == eight)
        {
            display.setText(display.getText() + "8");
        }
        else if(event.getSource() == nine)
        {
            display.setText(display.getText() + "9");
        }
        else if(event.getSource() == zero)
        {
            display.setText(display.getText() + "0");
        }
        else if(event.getSource() == clear)
        {
            display.setText("");
        }
        else if(event.getSource() == add)
        {
            data = Float.parseFloat(display.getText());
            operation = 1;
            display.setText("");
        }
        else if(event.getSource() == minus)
        {
            data = Float.parseFloat(display.getText());
            operation = 2;
            display.setText("");
        }
        else if(event.getSource() == multi)
        {
            data = Float.parseFloat(display.getText());
            operation = 3;
            display.setText("");
        }
        else if(event.getSource() == divide)
        {
            data = Float.parseFloat(display.getText());
            operation = 4;
            display.setText("");
        }
        else if(event.getSource() == equals)
        {
            Float secondOperand = Float.parseFloat(display.getText());
            switch(operation)
            {
                case 1: //Addition
                    Double ans = data + secondOperand;
                    display.setText(String.valueOf(ans));
                    //data = ans;
                    break;
                case 2: //Subtraction
                    ans = data - secondOperand;
                    display.setText(String.valueOf(ans));
                    //data = ans;
                    break;
                case 3: //Multiplication
                    ans = data * secondOperand;
                    display.setText(String.valueOf(ans));
                    //data = ans;
                    break;
                case 4: //Division
                    ans = 0d;
                    try{
                        ans = data / secondOperand;
                    }catch(Exception ex){display.setText("Error");}
                    display.setText(String.valueOf(ans));
                    //data = ans;
                    break;
            }
//            if(event.getSource() != divide && event.getSource() != add && event.getSource() != multi && event.getSource() != minus)
//            {
//                start = true;
//            }
        }
    }
    @FXML
    private void send2sceneconver(ActionEvent event) throws Exception{
        Parent rootBMI = FXMLLoader.load(getClass().getResource("ConversionCal.fxml"));
        Scene scene2 = new Scene(rootBMI);
        Stage calS = (Stage) ((Node) event.getSource()).getScene().getWindow();
        calS.setScene(scene2);
        calS.show();
    }
    @Override
    public void initialize(URL url, ResourceBundle rb) {
        // TODO
    }
}

另外请注意，如果您不使用它，您可以删除implements Initializable

我还想出了另一种方法，在 [data =] 之前声明 [操作 =]，如下所示：

        else if(event.getSource() == divide)
        {
            operation = -1;
            operation = 4;
            data = Float.parseFloat(display.getText());
            display.setText("");
            dot.setDisable(false);
        }

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