java - JOptionPane 错误 Java-6ren

java - JOptionPane 错误 Java

转载作者：行者123 更新时间：2023-12-02 02:57:36

我正在尝试制作一个 GPA 计算器应用程序。我已经掌握了所有必要的代码。只是当我尝试制作 GUI 时，我收到了一个我根本不理解的错误代码。

代码:

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Scanner;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class Caculator{

    public static void main(String args[]){

        Scanner ream = new Scanner(System.in);
        String firstnumber = "";
        double firstdec;
        String secondnumber = "";
        double seconddec;
        String thirdnumber = "";
        double thirddec;
        String fourthnumber = "";
        double fourthdec;
        String fifthnumber = "";
        double fifthdec;
        String sixthnumber = "";
        double sixthdec;
        String seventhnumber = "";
        double seventhdec;
        String eighthnumber = "";
        double eighthdec;
        double total = 0;
        JTextField GPA = new JTextField();

    JFrame panel = new JFrame();
    panel.add(new JLabel("First Grade"));
    panel.add(new JLabel("Second Grade"));
    panel.add(new JTextField(firstnumber));
    panel.add(new JTextField(secondnumber));
    panel.add(new JLabel("Third Grade"));
    panel.add(new JLabel("Fourth Grade"));
    panel.add(new JTextField(thirdnumber));
    panel.add(new JTextField(fourthnumber));
    panel.add(new JLabel("Fifth Grade"));
    panel.add(new JLabel("Sixth Grade"));
    panel.add(new JTextField(fifthnumber));
    panel.add(new JTextField(sixthnumber));
    panel.add(new JLabel("Seventh Grade"));
    panel.add(new JLabel("Eighth Grade"));
    panel.add(new JTextField(seventhnumber));
    panel.add(new JTextField(eighthnumber));

    int result = JOptionPane.showConfirmDialog(null, panel, "Quesion", JOptionPane.OK_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE);
    switch (result) {

        case JOptionPane.OK_OPTION:
            firstnumber = ream.nextLine();

            if (firstnumber.equals("A+")) {

            firstdec = 4.4;
                total += firstdec;

            } else

            if (firstnumber.equals("A")) {

                firstdec = 4.0;
                total += firstdec;

            } else

            if (firstnumber.equals("A-")) {

                firstdec = 3.7;
                total += firstdec;

            } else

            if (firstnumber.equals("B+")) {

                firstdec = 3.4;
                total += firstdec;

            } else

            if (firstnumber.equals("B")) {

                firstdec = 3.0;
                total += firstdec;

            } else

            if (firstnumber.equals("B-")) {

                firstdec = 2.7;
                total += firstdec;

            } else

            if (firstnumber.equals("C+")) {

                firstdec = 2.4;
                total += firstdec;

            } else

            if (firstnumber.equals("C")) {

                firstdec = 2.0;
                total += firstdec;

            } else

            if (firstnumber.equals("C-")) {

                firstdec = 1.7;
                total += firstdec;

            } else

            if (firstnumber.equals("F")) {

                firstdec = 0;
                total += firstdec;

            }

            secondnumber = ream.nextLine();

            if (secondnumber.equals("A+")) {

                seconddec = 4.4;
                total += seconddec;

            } else

            if (secondnumber.equals("A")) {

                seconddec = 4.0;
                total += seconddec;

            } else

            if (secondnumber.equals("A-")) {

                seconddec = 3.7;
                total += seconddec;

            } else

            if (secondnumber.equals("B+")) {

                seconddec = 3.4;
                total += seconddec;

            } else

            if (secondnumber.equals("B")) {

                seconddec = 3.0;
                total += seconddec;

            } else

            if (secondnumber.equals("B-")) {

                seconddec = 2.7;
                total += seconddec;

            } else

            if (secondnumber.equals("C+")) {

                seconddec = 2.4;
                total += seconddec;

            } else

            if (secondnumber.equals("C")) {

                seconddec = 2.0;
                total += seconddec;

            } else

            if (secondnumber.equals("C-")) {

                seconddec = 1.7;
                total += seconddec;

            } else

            if (secondnumber.equals("F")) {

                seconddec = 0;
                total += seconddec;

            }

            thirdnumber = ream.nextLine();

            if (thirdnumber.equals("A+")) {

                thirddec = 4.4;
                total += thirddec;

            } else

            if (thirdnumber.equals("A")) {

                thirddec = 4.0;
                total += thirddec;

            } else

            if (thirdnumber.equals("A-")) {

                thirddec = 3.7;
                total += thirddec;

            } else

            if (thirdnumber.equals("B+")) {

                thirddec = 3.4;
                total += thirddec;

            } else

            if (thirdnumber.equals("B")) {

                thirddec = 3.0;
                total += thirddec;

            } else

            if (thirdnumber.equals("B-")) {

                thirddec = 2.7;
                total += thirddec;

            } else

            if (thirdnumber.equals("C+")) {

                thirddec = 2.4;
                total += thirddec;

            } else

            if (thirdnumber.equals("C")) {

                thirddec = 2.0;
                total += thirddec;

            } else

            if (thirdnumber.equals("C-")) {

                thirddec = 1.7;
                total += thirddec;

            } else

            if (thirdnumber.equals("F")) {

                thirddec = 0;
                total += thirddec;

            }

            fourthnumber = ream.nextLine();

            if (fourthnumber.equals("A+")) {

                fourthdec = 4.4;
                total += fourthdec;

            } else

            if (fourthnumber.equals("A")) {

                fourthdec = 4.0;
                total += fourthdec;

            } else

            if (fourthnumber.equals("A-")) {

                fourthdec = 3.7;
                total += fourthdec;

            } else

            if (fourthnumber.equals("B+")) {

                fourthdec = 3.4;
                total += fourthdec;

            } else

            if (fourthnumber.equals("B")) {

                fourthdec = 3.0;
                total += fourthdec;

            } else

            if (fourthnumber.equals("B-")) {

                fourthdec = 2.7;
                total += fourthdec;

            } else

            if (fourthnumber.equals("C+")) {

                fourthdec = 2.4;
                total += fourthdec;

            } else

            if (fourthnumber.equals("C")) {

                fourthdec = 2.0;
                total += fourthdec;

            } else

            if (fourthnumber.equals("C-")) {

                fourthdec = 1.7;
                total += fourthdec;

            } else

            if (fourthnumber.equals("F")) {

                fourthdec = 0;
                total += fourthdec;

            }

            fifthnumber = ream.nextLine();

            if (fifthnumber.equals("A+")) {

                fifthdec = 4.4;
                total += fifthdec;

            } else

            if (fifthnumber.equals("A")) {

                fifthdec = 4.0;
                total += fifthdec;

            } else

            if (fifthnumber.equals("A-")) {

                fifthdec = 3.7;
                total += fifthdec;

            } else

            if (fifthnumber.equals("B+")) {

                fifthdec = 3.4;
                total += fifthdec;

            } else

            if (fifthnumber.equals("B")) {

                fifthdec = 3.0;
                total += fifthdec;

            } else

            if (fifthnumber.equals("B-")) {

                fifthdec = 2.7;
                total += fifthdec;

            } else

                if (fifthnumber.equals("C+")) {

                fifthdec = 2.4;
                    total += fifthdec;

            } else

            if (fifthnumber.equals("C")) {

                fifthdec = 2.0;
                total += fifthdec;

            } else

            if (fifthnumber.equals("C-")) {

                fifthdec = 1.7;
                total += fifthdec;

            } else

            if (fifthnumber.equals("F")) {

                fifthdec = 0;
                total += fifthdec;

            }

            sixthnumber = ream.nextLine();

            if (sixthnumber.equals("A+")) {

                sixthdec = 4.4;
                total += sixthdec;

            } else

            if (sixthnumber.equals("A")) {

                sixthdec = 4.0;
                total += sixthdec;

            } else

            if (sixthnumber.equals("A-")) {

                sixthdec = 3.7;
                total += sixthdec;

            } else

            if (sixthnumber.equals("B+")) {

                sixthdec = 3.4;
                total += sixthdec;

            } else

            if (sixthnumber.equals("B")) {

                sixthdec = 3.0;
                total += sixthdec;

            } else

            if (sixthnumber.equals("B-")) {

                sixthdec = 2.7;
                total += sixthdec;

            } else

            if (sixthnumber.equals("C+")) {

                sixthdec = 2.4;
                total += sixthdec;

            } else

            if (sixthnumber.equals("C")) {

                sixthdec = 2.0;
                total += sixthdec;

            } else

            if (sixthnumber.equals("C-")) {

                sixthdec = 1.7;
                total += sixthdec;

            } else

            if (sixthnumber.equals("F")) {

                sixthdec = 0;
                total += sixthdec;

            }

            seventhnumber = ream.nextLine();

            if (seventhnumber.equals("A+")) {

                seventhdec = 4.4;
                total += seventhdec;

            } else

            if (seventhnumber.equals("A")) {

                seventhdec = 4.0;
                total += seventhdec;

            } else

            if (seventhnumber.equals("A-")) {

                seventhdec = 3.7;
                total += seventhdec;

            } else

            if (seventhnumber.equals("B+")) {

                seventhdec = 3.4;
                total += seventhdec;

            } else

            if (seventhnumber.equals("B")) {

                seventhdec = 3.0;
                total += seventhdec;

            } else

            if (seventhnumber.equals("B-")) {

                seventhdec = 2.7;
                total += seventhdec;

            } else

            if (seventhnumber.equals("C+")) {

                seventhdec = 2.4;
                total += seventhdec;

            } else

            if (seventhnumber.equals("C")) {

                seventhdec = 2.0;
                total += seventhdec;

            } else

            if (seventhnumber.equals("C-")) {

                seventhdec = 1.7;
                total += seventhdec;

            } else

            if (seventhnumber.equals("F")) {

                seventhdec = 0;
                total += seventhdec;

            }

            eighthnumber = ream.nextLine();

            if (eighthnumber.equals("A+")) {

                eighthdec = 4.4;
                total += eighthdec;

            } else

            if (eighthnumber.equals("A")) {

                eighthdec = 4.0;
                total += eighthdec;

            } else

            if (eighthnumber.equals("A-")) {

                eighthdec = 3.7;
                total += eighthdec;

            } else

            if (eighthnumber.equals("B+")) {

                eighthdec = 3.4;
                total += eighthdec;

            } else

            if (eighthnumber.equals("B")) {

                eighthdec = 3.0;
                total += eighthdec;

            } else

            if (eighthnumber.equals("B-")) {

                eighthdec = 2.7;
                total += eighthdec;

            } else

            if (eighthnumber.equals("C+")) {

                eighthdec = 2.4;
                total += eighthdec;

            } else

            if (eighthnumber.equals("C")) {

                eighthdec = 2.0;
                total += eighthdec;

            } else

            if (eighthnumber.equals("C-")) {

                eighthdec = 1.7;
                total += eighthdec;

            } else

            if (eighthnumber.equals("F")) {

                eighthdec = 0;
                total += eighthdec;

            }

            JButton b1 = new JButton("Ok");
            b1.addActionListener(new ActionListener()
            {
                public void actionPerformed(ActionEvent e)
                {
                    panel.dispose();
                }
            });

            JPanel panel1 = new JPanel(new GridLayout(0, 4));
            panel1.add(new JLabel("Your GPA is: "));
            panel1.add(new JTextField());

            double gpa = Double.parseDouble(GPA.getText());

            gpa = total / 8;

            JFrame frame = new JFrame();
            JOptionPane.showInputDialog(frame, "Your GPA is" + gpa);


            break;
        case JOptionPane.CANCEL_OPTION:

            panel.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);

            break;
        }


}

    }

错误堆栈跟踪是

Exception in thread "main" java.lang.IllegalArgumentException: adding a window to a container
    at java.awt.Container.checkNotAWindow(Container.java:490)
    at java.awt.Container.addImpl(Container.java:1091)
    at java.awt.Container.add(Container.java:973)
    at javax.swing.plaf.basic.BasicOptionPaneUI.addMessageComponents(BasicOptionPaneUI.java:358)
    at com.apple.laf.AquaOptionPaneUI.createMessageArea(AquaOptionPaneUI.java:92)
    at javax.swing.plaf.basic.BasicOptionPaneUI.installComponents(BasicOptionPaneUI.java:172)
    at javax.swing.plaf.basic.BasicOptionPaneUI.installUI(BasicOptionPaneUI.java:141)
    at javax.swing.JComponent.setUI(JComponent.java:666)
    at javax.swing.JOptionPane.setUI(JOptionPane.java:1860)
    at javax.swing.JOptionPane.updateUI(JOptionPane.java:1882)
    at javax.swing.JOptionPane.<init>(JOptionPane.java:1845)
    at javax.swing.JOptionPane.showOptionDialog(JOptionPane.java:857)
    at javax.swing.JOptionPane.showConfirmDialog(JOptionPane.java:795)
    at javax.swing.JOptionPane.showConfirmDialog(JOptionPane.java:757)
    at Caculator.main(Caculator.java:55)

如果我点击“at Caculator.main(caculator.java:55)它把我带到了这一行

int result = JOptionPane.showConfirmDialog(null, panel, "Quesion", JOptionPane.OK_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE);

最佳答案

错误消息准确地告诉您错误所在以及错误位置。

您的panel对象的类型为JFrame，它是一个容器。您无法将容器添加到对话框，这正是您在以下行中尝试执行的操作:

int result = JOptionPane.showConfirmDialog(null, panel, "Quesion", JOptionPane.OK_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE);

将面板更改为JPanel。您将需要进行更多更正，例如:

删除此项，因为 JPanel 不存在 dispose() 方法:
```
panel.dispose();
```
并删除它，因为 JPanel 不存在 setDefaultCloseOperation() 方法:
```
panel.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
```

<小时/>

这是您的 GPA 计算器的工作副本。

我已显着简化了您的类(class)，将计算 GPA 点的逻辑合并到一个单独的方法中。
我将所有 String 变量更改为 JTextField，因为您需要文本字段的实例来获取在每个字段中输入的文本。

<小时/>

import java.awt.GridLayout;

import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class Caculator {
    public static void main(String args[]) {
        JPanel panel = new JPanel(new GridLayout(8, 2));

        JTextField firstnumber = new JTextField(20);
        JTextField secondnumber = new JTextField(20);
        JTextField thirdnumber = new JTextField(20);
        JTextField fourthnumber = new JTextField(20);
        JTextField fifthnumber = new JTextField(20);
        JTextField sixthnumber = new JTextField(20);
        JTextField seventhnumber = new JTextField(20);
        JTextField eighthnumber = new JTextField(20);

        panel.add(new JLabel("First Grade"));
        panel.add(new JLabel("Second Grade"));
        panel.add(firstnumber);
        panel.add(secondnumber);
        panel.add(new JLabel("Third Grade"));
        panel.add(new JLabel("Fourth Grade"));
        panel.add(thirdnumber);
        panel.add(fourthnumber);
        panel.add(new JLabel("Fifth Grade"));
        panel.add(new JLabel("Sixth Grade"));
        panel.add(fifthnumber);
        panel.add(sixthnumber);
        panel.add(new JLabel("Seventh Grade"));
        panel.add(new JLabel("Eighth Grade"));
        panel.add(seventhnumber);
        panel.add(eighthnumber);

        int result = JOptionPane.showConfirmDialog(null, panel, "Quesion", JOptionPane.OK_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE);

        double total = 0;
        if (result == JOptionPane.OK_OPTION) {
            total += getPoints(firstnumber.getText());

            total += getPoints(firstnumber.getText());

            total += getPoints(thirdnumber.getText());

            total += getPoints(fourthnumber.getText());

            total += getPoints(fifthnumber.getText());

            total += getPoints(sixthnumber.getText());

            total += getPoints(seventhnumber.getText());

            total += getPoints(eighthnumber.getText());

            JTextField GPA = new JTextField(20);

            JPanel panel1 = new JPanel(new GridLayout(2, 2));
            panel1.add(new JLabel("Your GPA is: "));
            panel1.add(GPA);

            double gpa = total / 8;
            GPA.setText(String.valueOf(gpa));

            JOptionPane.showMessageDialog(null, panel1);
        }
    }

    static double getPoints(String grade) {
        double points = 0;
        if (grade.equals("A+")) {
            points = 4.4;
        } else if (grade.equals("A")) {
            points = 4.0;
        } else if (grade.equals("A-")) {
            points = 3.7;
        } else if (grade.equals("B+")) {
            points = 3.4;
        } else if (grade.equals("B")) {
            points = 3.0;
        } else if (grade.equals("B-")) {
            points = 2.7;
        } else if (grade.equals("C+")) {
            points = 2.4;
        } else if (grade.equals("C")) {
            points = 2.0;
        } else if (grade.equals("C-")) {
            points = 1.7;
        } else if (grade.equals("F")) {
            points = 0;
        }
        return points;
    }
}

<小时/>

希望这有帮助。

关于java - JOptionPane 错误 Java，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/42851005/

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java - JOptionPane 错误 Java