for循环(i)在循环外使用的变量或可能的解决方案

Question

我正试图为startTextFieldListener找到一种方法来访问for循环中的一些变量。有办法做到这一点吗？如果有一个简单的解决方案，我很抱歉，但我不太确定如何解决这个问题。我看过一些例子，但我不知道如何将其应用到我的程序中。如有任何帮助，我们将不胜感激。

public class TextArea1{
JTextArea text;
JFrame frame;
JTextField textField;
public int k;
public ArrayList aList;
public String correctAnswer;
public static void main (String [] args) {
    TextArea1 gui = new TextArea1();
    gui.go();
}
private String textLine;
public void go() {
    frame = new JFrame();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    JPanel panel = new JPanel();
    textField = new JTextField("");
    textField.addActionListener(new startTextFieldListener(aList));
    JButton startButton  = new JButton ("Start!");
    startButton.addActionListener(new startButtonListener(aList));

    text = new JTextArea (30, 60);
    text.setLineWrap(true);
    JScrollPane scroller = new JScrollPane(text);
    scroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
    scroller.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
    panel.add(scroller);
    frame.getContentPane().add(BorderLayout.CENTER, panel);
    frame.getContentPane().add(BorderLayout.WEST, startButton);
    frame.getContentPane().add(BorderLayout.SOUTH, textField);      
    frame.setSize(350, 300);
    frame.setVisible(true);
}       

class startButtonListener implements ActionListener {
 ArrayList aList;
 startButtonListener(ArrayList passedInList)
 {
      aList = passedInList;
 }
 @Override
public void actionPerformed(ActionEvent event) {
     String fileName = "test.txt";
    String line;
    ArrayList aList = new ArrayList();
    try {
         try (BufferedReader input = new BufferedReader (new FileReader(fileName))) {
             if (!input.ready())   {
                 throw new IOException();
             }
             while ((line = input.readLine()) !=null) {
                 aList.add(line);
             }}
    } catch (IOException e) {
        System.out.println(e);
    }
    int sz = aList.size();
       for (int k = 0; k< sz; k++) {          
        String correctAnswer = aList.get(k).toString();
    text.append(aList.get(k).toString());
    text.append("n");
       }   
}
}       
    class startTextFieldListener implements ActionListener {
         startTextFieldListener(ArrayList passedInList)
         {
             aList = passedInList;
         }


         @Override
        public void actionPerformed(ActionEvent event) {
            text.getText();
             if (text.getText().equals(correctAnswer)) {
                JOptionPane.showMessageDialog(null, "Hooray!");
             }
             else if (!text.getText().equals(correctAnswer)) {
                JOptionPane.showMessageDialog(null, "Wrong!");

             }
            }

             }
        }

Answer 1

您可以尝试通过使整个类都可以访问变量来实现这一点。

要实现这一点，可以在类声明之后，在声明用户界面项的位置添加变量声明。

然后可以在另一个类中访问此变量。

示例代码：

public class TextArea1{
JTextArea text;
JFrame frame;
JTextField textField;
public int sampleIntToBeUsed;

您还可以使用各种get/set方法来实现这一点。

如何创建构造函数：（输入没有返回类型的类的名称）

class startButtonListener implements ActionListener {
     ArrayList aList;
     startButtonListener(ArrayList passedInList)
     {
          aList = passedInList;
     }

新的第二ActionListener

class startTextFieldListener implements ActionListener {
     String correctAnswer;
     startTextFieldListener(String answer)
     {
         correctAnswer = answer;
     }
         @Override
        public void actionPerformed(ActionEvent event) {
             if (text.getText().equals(correctAnswer)) {
                JOptionPane.showMessageDialog(null, "Hooray!");
             }
             else {
                JOptionPane.showMessageDialog(null, "Wrong!");
             }
          }
     }
    }