java - 为什么我的代码不起作用？

Question

此方法应该将下一个问题加载到 GUI 中。

public void readNextEntry() {

    list = new ArrayList<String>();

    scanner = new Scanner(linesFromFile.get(currentQuestion)).useDelimiter(",|\n");
    for (int i = 0; i < 8; i++) {
        list.add(scanner.next());
    }
}

它应该加载的文本文件格式如下:

001,what color is the sky,it is blue because of precipitation,green,blue,yellow,red,a,   
002,What color are my eyes,they are blue if you look,blue,brown,green,black,a,    
003,What color is the water,it is blue because of water,green,blue,red,yellow,b,

为什么不起作用？它应该加载类别(001)、问题(天空是什么颜色？)以及它的选择(绿色、蓝色、黄色，红色)。我的正则表达式关闭了吗？

编辑: 一些上下文，这是完整的代码。到目前为止，一直在尝试此线程的建议，但没有成功。

package TestAssignment;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.*;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;
import javax.swing.*;
import javax.swing.border.Border;

public class TestGui extends JFrame implements ActionListener {

private int counter = 0;
private int totalCount = 0;
private JTextArea question = new JTextArea();
private JTextArea recomendedAnswer = new JTextArea();
private JTextArea category = new JTextArea();
private ArrayList<String> list;
private ArrayList<String> linesFromFile;
private int currentQuestion = 0;
private ButtonGroup group = new ButtonGroup();
private ArrayList<JRadioButton> theButtons;
private JLabel response = new JLabel("");
private JButton answer = new JButton("Answer Question");
private Border border = BorderFactory.createLineBorder(Color.BLACK, 1);
private Scanner scanner;
private String fileName;

public void readNextEntry() {

    list = new ArrayList<String>();

    scanner = new Scanner(linesFromFile.get(currentQuestion)).useDelimiter(",|\n");
    for (int i = 0; i < 8; i++) {
        list.add(scanner.next());
    }
}

public void readFile() {
    linesFromFile = new ArrayList<String>();
    list = new ArrayList<String>();
    try {

        scanner = new Scanner(new File(fileName));
        while (scanner.hasNextLine()) {
            linesFromFile.add(scanner.nextLine());
        }
        Collections.shuffle(linesFromFile);
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }
}

public TestGui(String in) {

    setLayout(new GridLayout(11, 25));
    this.fileName = in;

    add(new JLabel("Category : "));
    JScrollPane scrollPane1 = new JScrollPane(category);
    category.setLineWrap(true);
    category.setBorder(border);
    add(scrollPane1);
    category.setEditable(false);

    //int randomNumber = (int) (Math.random() * 10) + 1;
    //String line = TestGui.readFileByLine("Questions.txt", randomNumber);

    add(new JLabel("Question: "));
    JScrollPane scrollPane2 = new JScrollPane(question);
    question.setLineWrap(true);
    question.setBorder(border);
    add(scrollPane2);
    question.setEditable(false);

    readFile();
    readNextEntry();

    add(new JLabel("Please Select the correct Answer"));

    theButtons = new ArrayList<JRadioButton>();

    for (int i = 0; i < 4; i++) {
        JRadioButton temp = new JRadioButton();
        theButtons.add(temp);
        add(temp);
        group.add(temp);
    }
    refreshButtonLabels();

    add(response);

    category.setText(list.get(0));
    question.setText(list.get(1));

    add(answer);

    answer.addActionListener(this);
   }

  public void refreshButtonLabels() {
    for (int i = 0; i < 4; i++) {
        theButtons.get(i).setText(list.get(i + 3));
    }
  }

    @Override
    public void actionPerformed(ActionEvent e) {
    if (e.getSource() == answer) {
        for (int i = 0; i < theButtons.size(); i++) {
            JRadioButton button = theButtons.get(i);
            if (button.isSelected() && list.get(7).equals("a")) {
                counter++;
                readNextEntry();
            }
            else if (button.isSelected() && list.get(7).equals("b")){
                counter++;
                readNextEntry();
            }
             else if (button.isSelected() && list.get(7).equals("c")){
                counter++;
                readNextEntry();
            }
             else if (button.isSelected() && list.get(7).equals("d")){
                counter++;
                readNextEntry();

            }
        }
    }
     else {
           readNextEntry();
          {
    }
    }





package TestAssignment;

import javax.swing.JFrame;


public class Test {
public static void main(String[] args) {
    TestGui test = new TestGui();
    test.setVisible(true);
    test.setSize(600, 600);
    test.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

}
}

Answer 1

您会发现用逗号分隔字符串要容易得多:

String line = linesFromFile.get(currentQuestion);
String[] list = line.split(",\\s*");

扫描仪只是妨碍你。但是，当您确实使用扫描程序时，切勿在未先调用关联的 hasNextXXX() 方法的情况下调用其 nextXXX() 方法之一。例如:

while (scanner.hasNext())
{
  list.add(scanner.next());
}

如果使用正确，Scanner 永远不会抛出 NoSuchElementException。