.setBackground（）方法不适用于JRadioButton

Question

我正在编写一个具有测验元素的程序，当用户得到错误答案时，就会给出反馈。 问题JFrame由具有实际问题的JLabel和具有不同选项（名为rad1，rad2，rad3，rad4）的4个JRadioButton组成。 我要尝试做的是，如果用户弄错了答案，则具有正确答案背景颜色的单选按钮将变为绿色，而具有用户给出背景答案的单选按钮将变为红色。

这是我用来确定哪个答案正确的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
    }
}                    

我一直在使用.setBackground（）方法一段时间，如果我将print语句放在case块中，它们会执行，但是不会发生着色。 我缺少什么笨蛋吗？

谢谢

编辑：添加了更多代码，以查看FOR循环在btnSubmitActionPerformed（）方法内。 当用户单击按钮时，将判断其答案，并更改单选按钮的颜色。

Answer 1

马上想到两件事：

1. 您发布的代码从哪里调用？ 在Swing工作线程之外进行UI更改是不确定的。 有时正确的事情会发生，而其他时候则不会。
2. 我从未尝试过在单选按钮上设置颜色，但似乎它们没有背景。

尝试设置其他属性，例如大小，以查看是否获得结果。 如果是这样，那么问题就在于单选按钮没有背景，您将不得不提出另一种设计。 如果什么都没有发生，那可能是第一个问题。

Answer 2

您希望代码过于复杂和不必要。 我自己，我会尝试“ OOP化”的东西来减少圈复杂度并

• 一个非GUI Question类，
• 带有一个用于questionText的字符串字段，
• 带有用于correctAnswer的字符串字段，
• 使用List<String>表示不正确的答案。
• 我会给它一个方法，例如public List<String> getShuffledAnswers() ，返回一个字符串列表，其中所有答案（正确和不正确）都在其自己的列表中public List<String> getShuffledAnswers()排列，
• 一个布尔方法testAnswer(String test) ，并且返回true的测试等于correctAnswer。

然后，我将创建一个名为QuestionPanel的JPanel

• 有一个问题字段
• 显示单个Question对象的信息，包括JLabel中的questionText和JRadioButtons中所有经过改组的答案。
• 它会有获取所选JRadioButton和获取Question的方法，
• 以及一种通过调用setOpaque（false）来设置使JRadioButtons背景在不透明时不透明的方法
• 还有一种方法，该方法允许调用代码使用正确的答案颜色或错误的答案颜色设置选择的JRadioButtons的背景。

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);
    }

}