Java-在radioButtons和JPanel中使用IsSelected函数

我必须用Java设置一个“测验”，使用

JPanel

和

JRadioButton

我的代码首先从一个文件中读取一个文本，然后把它放在一个面板上，面板上有单选按钮、按钮组和面板。到目前为止，一切顺利

然而，当我必须从用户那里收集数据并与正确答案进行比较时，我的问题就开始了

我有课堂问题，答案和阅读（除了主要的和显示在面板上）

我的想法是，当用户单击

submit

按钮时，代码开始检查以进行测验。但是，当我在打开的窗口上单击它时，什么也没有发生

我将数据收集到

ArrayList

中进行比较

checkquick

方法应该在用户提交测验后调用。它将单选按钮选择的文本与答案进行比较。该程序应该是“运行”，直到用户点击“提交”按钮，但我相信它不会发生

我试图在代码中使用

ActionListener

，但无法将用户的选择与我使用的数据进行比较

很抱歉代码太多。我试图发布一个mcve问题。据我所知，代码是可编译的，但我不能再忽略任何行

谢谢你的帮助，代码如下。

Class DisplayOnPanel为要使用的子类创建一个框架：

import javax.swing.JFrame;

public class DisplayOnPanel extends JFrame {
    JFrame frame = new JFrame();
    public DisplayOnPanel(){
        frame.setSize(500,500);
    }
}

public class Main {
public static void main (String[]args){
      new Read();
    }
}

public class Question {
private String _question;
private String _option1;
private String _option2;
private String _option3;
private String _option4;
private int _qIndex=0;
public Question(String question, String option1, String option2, String option3,
                String option4){
    this._question = question;
    this._option1 = option1;
    this._option2 = option2;
    this._option3 = option3;
    this._option4 = option4;


}
public void set_qIndex(int index) {
    this._qIndex = index;
}

主类：

import javax.swing.JFrame;

public class DisplayOnPanel extends JFrame {
    JFrame frame = new JFrame();
    public DisplayOnPanel(){
        frame.setSize(500,500);
    }
}

public class Main {
public static void main (String[]args){
      new Read();
    }
}

public class Question {
private String _question;
private String _option1;
private String _option2;
private String _option3;
private String _option4;
private int _qIndex=0;
public Question(String question, String option1, String option2, String option3,
                String option4){
    this._question = question;
    this._option1 = option1;
    this._option2 = option2;
    this._option3 = option3;
    this._option4 = option4;


}
public void set_qIndex(int index) {
    this._qIndex = index;
}

Clsas问题：

import javax.swing.JFrame;

public class DisplayOnPanel extends JFrame {
    JFrame frame = new JFrame();
    public DisplayOnPanel(){
        frame.setSize(500,500);
    }
}

public class Main {
public static void main (String[]args){
      new Read();
    }
}

public class Question {
private String _question;
private String _option1;
private String _option2;
private String _option3;
private String _option4;
private int _qIndex=0;
public Question(String question, String option1, String option2, String option3,
                String option4){
    this._question = question;
    this._option1 = option1;
    this._option2 = option2;
    this._option3 = option3;
    this._option4 = option4;


}
public void set_qIndex(int index) {
    this._qIndex = index;
}

类读取-读取文件，然后在面板上显示结果。它还用答案、问题、按钮组和JPanel填充数组列表

import javax.swing.*;
import java.awt.*;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.Scanner;
public class Read extends DisplayOnPanel {


protected ArrayList<Question> Questions = new ArrayList<>();
protected ArrayList<ButtonGroup> BG = new ArrayList<>();
protected ArrayList<JPanel> JP = new ArrayList<>();
protected ArrayList<Answer> Answers = new ArrayList<>();
protected int qNumber = 0, finalscore = 0;
private JLabel lblScore;
private JToggleButton Submit = new JToggleButton();
//constructor

public Read() {
    super();
    //a "label" in the file will indicate the final score
    final int NUMBER_OF_LABELS_ADDED_TO_FRAME = 1;
    int number_of_lines_in_the_file, final_score = 0;
    try {
        number_of_lines_in_the_file = read(Questions);
        addButtonsToFrame(Questions, number_of_lines_in_the_file +
                NUMBER_OF_LABELS_ADDED_TO_FRAME, BG, JP);
        Submit.setText("Submit Quiz"); //create a submit button
        JPanel SubmitPanel = new JPanel();
        SubmitPanel.setVisible(true);
        this.add(SubmitPanel);
        SubmitPanel.add(Submit);

Submit.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent arg0) {
                    for (int i = 0; i < BG.size(); i++) {
                        //handle cases of the user didn't complete the test
                        if (BG.get(i).getSelection()==null) {
                            JOptionPane.showMessageDialog(frame, "Exam not finished - Restart.");
                            i=BG.size()-1; //finish the loop
                            frame.setVisible(false);
                            dispose();
                            new Read();
                        }
                    }
                    checkQuiz(BG, Answers, ONE_QUESTION_GRADE); //check quiz
                    Submit.setEnabled(false); //can't redo quiz //
                    // unless "Restart" pressed


                }
            });            
//adding final score label
        lblScore = new JLabel("Your Final Score: " + finalscore);
        add(lblScore);
        pack();
        this.setVisible(true);
        while (!Submit.isSelected()) {
            if (Submit.isSelected()) {
                checkQuiz(BG, Answers);
            }
        }
    } catch (FileNotFoundException e) {
        System.out.println("couldn't open file");
    }
}
//the method reads from the file


//returns the number of lines (quesiton) in the file

public int read(ArrayList<Question> Questions) throws FileNotFoundException {
    int number_of_lines = 0;
    try {
        File f = new File("C:\\Users\\Assaf\\Desktop\\exam.txt");
        Scanner input = new Scanner(f);
        //read from file direcly into the constructor
        while (input.hasNext()) {
            Question q = new Question((input.nextLine())
                    , (input.nextLine()),
                    (input.nextLine()),
                    (input.nextLine()),
                    (input.nextLine()));
            //adding the question and the answers to an array
            Questions.add(q);
            number_of_lines++;
            q.set_qIndex(number_of_lines);
            Answers.add(new Answer(q));

        }
        input.close();
    } catch (FileNotFoundException nf) {
        System.out.println("couldn't open file");
    }
    //return number of lines in the file
    return number_of_lines;
}
public void addButtonsToFrame(ArrayList<Question> q, int number_of_lines,
                              ArrayList<ButtonGroup> BG, ArrayList<JPanel> JP) {
    int j = 0;
    for (int i = 0; i < q.size(); i++) {
        qNumber = i;
        BG.add(new ButtonGroup());
        JP.add(new JPanel());
        JP.get(i).setSize(499, 400);
        //creating buttons
JRadioButton option1 = new JRadioButton(q.get(i).get_option1());
option1.setActionCommand(q.get(i).get_option1());
JRadioButton option2 = new JRadioButton(q.get(i).get_option2());
option2.setActionCommand(q.get(i).get_option2());
JRadioButton option3 = new JRadioButton(q.get(i).get_option3());
option3.setActionCommand(q.get(i).get_option3());
JRadioButton option4 = new JRadioButton(q.get(i).get_option4());
option4.setActionCommand(q.get(i).get_option4());
        //adding to group buttons
        BG.get(j).add(option1);
        BG.get(j).add(option2);
        BG.get(j).add(option3);
        BG.get(j).add(option4);
        //adding the buttons to the panel
        JP.get(j).add(option1);
        JP.get(j).add(option2);
        JP.get(j).add(option3);
        JP.get(j).add(option4);
        //setting layout that matches our goal
        this.setLayout(new GridLayout(number_of_lines + 1, 1));
        //set title and border for each question
        JP.get(i).setBorder(BorderFactory.createTitledBorder(
                BorderFactory.createEtchedBorder(), "question number " + qNumber + ": " + q.get(i).get_question()));
        //adding the panel to the frame
        this.add(JP.get(j));
        //BG.get(i).getSelection()
        JP.get(j).setVisible(true);
        j++;
    }
}
public void checkQuiz(ArrayList<ButtonGroup> BG, ArrayList<Answer> A) {
    ArrayList<String> Selections = new ArrayList<>();
    int CORRECT_ANSWER = 0;
    for (int i = 0; i < BG.size(); i++) {
        if (BG.get(i).getSelection().getActionCommand()
                .compareTo(A.get(i).get_answer()) == CORRECT_ANSWER) {
            finalscore = finalscore + 10;
        }
    }

}

编辑- 发布了我的工作代码。

i）您需要在获取操作命令之前设置它，

JRadioButton option1 = new JRadioButton(q.get(i).get_option1());
option1.setActionCommand(q.get(i).get_option1());
JRadioButton option2 = new JRadioButton(q.get(i).get_option2());
option2.setActionCommand(q.get(i).get_option2());
JRadioButton option3 = new JRadioButton(q.get(i).get_option3());
option3.setActionCommand(q.get(i).get_option3());
JRadioButton option4 = new JRadioButton(q.get(i).get_option4());
option4.setActionCommand(q.get(i).get_option4());

ii）您尚未在

checkquick

方法的末尾设置标签中的最终分数，

lblScore.setText（“您的最终分数：+finalscore”）

iii）不建议使用
while
循环。另外，您使用的当前逻辑在大多数情况下都不会调用
checkquick
方法。因此，使用
ActionListener
接口，而不是
while

Submit.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent arg0) {
         checkQuiz(BG, Answers);
    }
});

我在您的代码中找不到任何
EventListener
。另外，您在
DisplayOnPanel
中创建的
frame
对象没有任何用处，因为它在任何地方都没有使用。这里，EventListener的问题是，由于我尝试与CheckQuike方法进行比较，因此得到了nullPointerException。我如何使用它？非常感谢。我尝试使用EvenListener—发现我无法调用另一个与数组一起工作的方法—一直都会出现null异常。
“在用户单击“提交”按钮之前，程序应该是“运行”的，但我相信它不会发生。”
swing不是这样工作的。您不需要循环，这将冻结您的gui。只需在提交按钮上使用
ActionListener
，并在事件发生时（单击按钮或按键）在单选按钮上使用
isSelected（）
，检查选择了哪些单选按钮。谢谢@Ansharja，这是一个好主意-但我尝试这样做时会得到一个空异常。当我出于某种原因这样做时，BG和其他数组都是空的。谢谢！！！“setActionCommand”与“常规”ActionListener不具备的功能是什么？
setActionCommand
以
String
格式设置操作命令，这有助于您在
ActionListener
中识别要执行的操作和
ActionEvent