java - panel.setFocusable() 不起作用

Question

我正在制作一个程序，允许用户在 JTextField 中输入文件路径，并在单击“查看”JButton 或按下 Enter 键时在 JTextArea 中显示文件的内容。

问题:单击“查看”按钮即可(显示文件内容)。但是，回车键不起作用。我认为 southPanel.setFocusable(true) 很困惑。

import java.awt.BorderLayout;
import java.awt.event.*;
import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
import javax.swing.*;

public class CFrame extends JFrame{
JTextArea outputTextArea = new JTextArea(); // Create a TextArea on which the contents of the file will be displayed
JPanel southPanel = new JPanel(); // Create a panel to be placed at the bottom of the frame
JScrollPane output = new JScrollPane(outputTextArea); // Create a ScrollPane for outputTextArea
JButton view = new JButton("View"); // This button, when clicked, displays the file's contents in outputTextArea
JTextField fileNameField = new JTextField(); // File Path/Name is entered in this field
CFrame() {
    southPanel.setFocusable(true);
    southPanel.addKeyListener(new KeyAdapter() {
        @Override
        public void keyPressed(KeyEvent e) {
            if(e.getKeyCode() == e.VK_ENTER) {
                view.setEnabled(true);
            }
        }
    });
    southPanel.setLayout(new BorderLayout());
    southPanel.add(fileNameField,BorderLayout.CENTER);
    southPanel.add(new JLabel("  File Name:  "), BorderLayout.WEST);
    southPanel.add(view, BorderLayout.EAST);
    outputTextArea.setEditable(false);
    setLayout(new BorderLayout(0,1));
    add(output,BorderLayout.CENTER);
    add(southPanel,BorderLayout.SOUTH);
    view.addActionListener(new ButtonListener());
}

public class ButtonListener implements ActionListener {
    @Override
    public void actionPerformed(ActionEvent e) {
        String fileName = fileNameField.getText();
        String data = "";
        File file = new File(fileName);
        try {
            Scanner input = new Scanner(file);
            while(input.hasNextLine()) {
                data = data + input.nextLine() + "\n\r";
            }
            outputTextArea.setText(data);
        }
        catch(FileNotFoundException ex) {
            System.out.println("No such file");
        }
        southPanel.requestFocusInWindow();
    }
}
}

Answer 1

enter file path in a JTextField and displays the contents of the file in a JTextArea when the "View" JButton is clicked or the Enter Key is pressed

你的设计是错误的。您不应尝试监听面板上的 Enter 键。

将 ActionListener 添加到文本字段。如果文本字段具有焦点并且您按 Enter 键，则会调用 ActionListener。