.setBackground()方法不适用于JRadioButton

Question

我正在编写一个包含问答元素的程序，当用户答错答案时，会给出反馈。问题JFrame由一个具有实际问题的JLabel和4个具有不同选项（命名为rad1、rad2、rad3、rad4）的JRadioButton组成。我想做的是，如果用户答错了答案，带有正确答案背景色的单选按钮将变为绿色，带有用户给出的答案的单选按钮的背景将变为红色。

这是我用来判断哪个答案是正确的FOR循环：

private void btnSubmitActionPerformed(java.awt.event.ActionEvent evt) {                                          
    System.out.println("Submit Clicked");
    //figures out what choice the user selected
    String correctAnswer = questions.get(current).getAnswer();
    int numChoice = -1;
    String choice = "";
    boolean answered = false;
    if (rad1.isSelected()) {
        numChoice = 0;
        answered = true;
        choice = rad1.getText();
    } else if (rad2.isSelected()) {
        numChoice = 1;
        answered = true;
        choice = rad2.getText();
    } else if (rad3.isSelected()) {
        numChoice = 2;
        answered = true;
        choice = rad3.getText();
    } else if (rad4.isSelected()) {
        numChoice = 3;
        answered = true;
        choice = rad4.getText();
    } else { //user didn't pick a choice
        JOptionPane.showMessageDialog(null, "You didn't answer the question, try again!");
    }
    if (choice.equals(correctAnswer)) {
        score++;
        System.out.println("score++");
    } else {
        //figures out which of the answers was correct
        rad1.setBackground(Color.RED);
        for (int i = 0; i < 4; i++) {
            if (questions.get(current).getChoices()[i].equals(correctAnswer)) {
                System.out.println(correctAnswer);
                System.out.println(i);
                //me trying to see if it will change if I put it outside the switch
                //confirmed that it will not.
                rad1.setBackground(Color.RED);
                switch (i) {
                    case 0:
                        rad1.setBackground(new Color(51, 204, 51));
                        break;
                    case 1:
                        rad2.setBackground(new Color(51, 204, 51));
                        break;
                    case 2:
                        rad3.setBackground(new Color(51, 204, 51));
                        break;
                    case 3:
                        rad4.setBackground(new Color(51, 204, 51));
                        break;
                }
                break;
            }
        }
        switch (numChoice) {
            case 0:
                rad1.setBackground(new Color(153, 0, 0));
                break;
            case 1:
                rad2.setBackground(new Color(153, 0, 0));
                break;
            case 2:
                rad3.setBackground(new Color(153, 0, 0));
                break;
            case 3:
                rad4.setBackground(new Color(153, 0, 0));
                break;
        }
    }
    //loads next question

    //loads the next question
    if (current < 10) {
        updateFrame();
    } else {
        //ends the quiz
    }
}                    

我使用.setBackground（）方法已经有一段时间了，如果我在case块中放入print语句，它们就会执行，但着色不会发生。我是不是错过了什么愚蠢的东西？

感谢

EDIT：添加了更多代码来查看FOR循环是否在btnSubmitActionPerformed（）方法中。当用户点击按钮时，将判断他们的答案，并更改单选按钮的颜色。

Answer 1

您的代码看起来过于复杂且不必要。就我自己而言，我会尝试"OOP ify"来降低循环复杂性并使用

• 一个非GUI问题类
• 具有questionText的字符串字段
• 具有correctAnswer的字符串字段
• List<String>表示答案不正确
• 我给它一个方法，比如public List<String> getShuffledAnswers()，返回一个字符串列表，其中包含所有正确和不正确的答案，并在它们自己的列表中混洗
• 一个布尔方法到testAnswer(String test)，并返回true的测试等于correctAnswer

然后我会创建一个名为QuestionPanel 的JPanel

• 具有"问题"字段
• 显示单个Question对象的信息，包括JLabel中的questionText和JRadioButtons中所有打乱的答案
• 它将具有用于获取所选JRadioButton和用于获取问题的方法
• 以及一种在需要时设置使JRadioButtons背景不透明的方法，方法是调用`setOpaque（false）
• 以及一种方法，允许调用代码将select JRadioButtons的背景设置为正确的答案颜色或错误的答案颜色

例如：

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import javax.swing.AbstractAction;
import javax.swing.BorderFactory;
import javax.swing.ButtonGroup;
import javax.swing.ButtonModel;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.SwingUtilities;
@SuppressWarnings("serial")
public class TestQuestions extends JPanel {
    private static final Question TEST_QUESTION = new Question("Select the Correct Answer", "This answer is correct", 
            "Incorrect Answer 1", "Incorrect Answer 2", "Incorrect Answer 3");
    private QuestionPanel questionPanel = new QuestionPanel();
    public TestQuestions() {
        questionPanel.setQuestion(TEST_QUESTION);
        JButton testAnswerBtn = new JButton(new AbstractAction("Test Answer") {
            @Override
            public void actionPerformed(ActionEvent e) {
                boolean isCorrect = questionPanel.isCorrectAnswerSelected();
                String message = "";
                if (isCorrect) {
                    message = "Correct answer selected!";
                } else {
                    message = "Incorrect answer selected!";                    
                }
                JOptionPane.showMessageDialog(TestQuestions.this, message);
                questionPanel.displayCorrectWrongAnswers();
            }
        });
        JButton clearAllBtn = new JButton(new AbstractAction("Clear All") {
            @Override
            public void actionPerformed(ActionEvent e) {
                questionPanel.clearAll();
                questionPanel.clearSelection();
            }
        });
        JPanel btnPanel = new JPanel(new GridLayout(1, 0, 5, 5));
        btnPanel.add(testAnswerBtn);
        btnPanel.add(clearAllBtn);
        setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
        setLayout(new BorderLayout(5, 5));
        add(questionPanel, BorderLayout.CENTER);
        add(btnPanel, BorderLayout.PAGE_END);
    }
    private static void createAndShowGui() {
        JFrame frame = new JFrame("TestQuestions");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(new TestQuestions());
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGui();
            }
        });
    }
}
@SuppressWarnings("serial")
class QuestionPanel extends JPanel {
    private static final Color CORRECT_ANSWER_SELECTED_COLOR = new Color(151, 255, 151);
    private static final Color CORRECT_ANSWER_NOT_SELECTED_COLOR = new Color(151,151, 255);
    private static final Color INCORRECT_ANSWER_SELECTED_COLOR = new Color(255, 151, 151);
    private Question question;
    private JLabel questionTextLabel = new JLabel();
    private List<JRadioButton> answerButtonList = new ArrayList<>();
    private JPanel answerPanel = new JPanel(new GridLayout(0, 1));
    private ButtonGroup buttonGroup = new ButtonGroup();
    public QuestionPanel() {
        setLayout(new BorderLayout());
        add(questionTextLabel, BorderLayout.PAGE_START);
        add(answerPanel, BorderLayout.CENTER);
    }
    public void setQuestion(Question question) {
        this.question = question;
        questionTextLabel.setText(question.getQuestionText());
        answerPanel.removeAll();
        answerButtonList.clear();
        buttonGroup = new ButtonGroup();
        for (String answer : question.getShuffledAnswers()) {
            JRadioButton rBtn = new JRadioButton(answer);
            rBtn.setActionCommand(answer);
            answerButtonList.add(rBtn);
            buttonGroup.add(rBtn);
            answerPanel.add(rBtn);
        }
    }
    public boolean isCorrectAnswerSelected() {
        ButtonModel model = buttonGroup.getSelection();
        if (model == null) {
            return false; // nothing selected
        } else {
            return question.checkAnswer(model.getActionCommand());
        }
    }
    public void clearAll() {
        for (JRadioButton jRadioButton : answerButtonList) {
            jRadioButton.setOpaque(false);
            jRadioButton.setBackground(null);
        }
    }
    public void clearSelection() {
        buttonGroup.clearSelection();
    }
    public void displayCorrectWrongAnswers() {
        clearAll();
        for (JRadioButton jRadioButton : answerButtonList) {
            if (jRadioButton.isSelected()) {
                jRadioButton.setOpaque(true);
                if (question.checkAnswer(jRadioButton.getActionCommand())) {
                    jRadioButton.setBackground(CORRECT_ANSWER_SELECTED_COLOR);
                } else {
                    jRadioButton.setBackground(CORRECT_ANSWER_NOT_SELECTED_COLOR);
                }
            } else if (question.checkAnswer(jRadioButton.getActionCommand())) {
                jRadioButton.setOpaque(true);
                jRadioButton.setBackground(INCORRECT_ANSWER_SELECTED_COLOR);
            }
        }
    }
}
class Question {
    private String questionText;
    private String correctAnswer;
    private List<String> incorrectAnswerList = new ArrayList<>();
    public Question(String questionText, String correctAnswer, String... incorrectAnswers) {
        this.questionText = questionText;
        this.correctAnswer = correctAnswer;
        for (String incorrectAnswer : incorrectAnswers) {
            incorrectAnswerList.add(incorrectAnswer);
        }
    }
    public String getQuestionText() {
        return questionText;
    }
    public String getCorrectAnswer() {
        return correctAnswer;
    }
    public List<String> getShuffledAnswers() {
        List<String> answers = new ArrayList<>(incorrectAnswerList);
        answers.add(correctAnswer);
        Collections.shuffle(answers);
        return answers;
    }
    public boolean checkAnswer(String test) {
        return correctAnswer.equalsIgnoreCase(test);
    }
}

Answer 2

脑海中浮现出两件直接的事情：

1. 你发布的代码是从哪里来的？在Swing工作线程之外进行UI更改有点未定义。有时会发生正确的事情，但有时不会
2. 我从来没有试过在单选按钮上设置颜色，但它们似乎没有背景

试着设置一些其他属性，比如大小，看看你是否得到了结果。如果是这样的话，那么问题是单选按钮没有背景，你必须想出另一种设计。如果什么都没发生，那么这可能是第一个问题。