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());
    }
}

它应该从中加载的文本文件如下所示：

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（what color is the sky?）及其选择（green,blue,yellow,red）。我的正则表达式了吗？

编辑：一点上下文，这是完整的代码。到目前为止，一直在尝试从这个线程的建议没有成功。

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

您会发现简单地将字符串拆分为逗号更容易：

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

扫描仪正在妨碍你。但是当您使用扫描仪时，从不调用其nextXXX()方法之一，而无需先调用相关的hasNextXXX()方法。例如：

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

正确使用，Scanner不应该抛出NoSuchElementException。

Answer 2

理论上这应该有用。令人困惑的事情是计算出你的代码片段中仅提示的变量类型。

static List<String> linesFromFile = new ArrayList<String>();
static {
    linesFromFile.add("001,what color is the sky,it is blue because of precipitation,green,blue,yellow,red,a,");
    linesFromFile.add("002,What color are my eyes,they are blue if you look,blue,brown,green,black,a,");
    linesFromFile.add("003,What color is the water,it is blue because of water,green,blue,red,yellow,b,");
}

public static void main(String[] args) {
    List<String> list = new ArrayList<String>();

    Scanner scanner = new Scanner(linesFromFile.get(1)).useDelimiter(",|\n");
    for (int i = 0; i < 8; i++) {
        list.add(scanner.next());
    }
    System.out.println(Arrays.toString(list.toArray()));
}

打印[002, What color are my eyes, they are blue if you look, blue, brown, green, black, a]

如果你已经用行分隔，为什么要用“\ n”来划界？似乎其中一条线没有足够的元素，就像你期望的那样。您应该在获取单个元素之前尝试输出该行（或者只是调试它）。

为什么我的代码不起作用？

2 个答案: