Java 我有一个KeyListener的内部类，该类返回一个错误，即；不是抽象的，不重写抽象方法“；

我有一个包含大约10个JTextFields的JPanel，我希望在键盘上单击向上或向下箭头后，能够将焦点设置在特定的textfield上。因此，如果中间的文本字段被集中并单击上箭头，焦点将转到上面的文本字段，同样，如果单击向下箭头，则焦点将集中在其下方的文本字段。我创建了一个键侦听器的内部类，其模式类似于我的ActionListener类，我认为我可以这样做。当我编译它时，似乎有一个错误

panelEncodeMain.HandleKeyListener不是抽象的，并且不会覆盖KeyListener中的抽象方法keyReleased（KeyEvent）

有人能帮我解决这些问题吗？提前谢谢

public panelEncodemain()
{
    //setBackground(Color.WHITE);
    setLayout(new GridBagLayout());
    GridBagConstraints c = new GridBagConstraints();

    HandleControlButton control = new HandleControlButton();
    HandleKeyListener keycontrol = new HandleKeyListener();

    btn_testing = new JButton("Test Focus");
    btn_testing.addActionListener(control);

    lbl_page = new JLabel("Page :");
    lbl_line = new JLabel("Line :");
    lbl_refpage = new JLabel("Ref. Page :");
    lbl_refline = new JLabel("Ref. Line :");
    lbl_transdate = new JLabel("Transaction Date :");
    lbl_desc = new JLabel("Description :");
    lbl_accountcode = new JLabel("Account Code :");
    lbl_codetype = new JLabel("Code Type :");
    lbl_issuedate = new JLabel("Issue Date :");
    lbl_amount = new JLabel("Amount :");

    lbl_page.setFont(new Font("Arial", Font.PLAIN, 20));
    lbl_line.setFont(new Font("Arial", Font.PLAIN, 20));
    lbl_refpage.setFont(new Font("Arial", Font.PLAIN, 20));
    lbl_refline.setFont(new Font("Arial", Font.PLAIN, 20));
    lbl_transdate.setFont(new Font("Arial", Font.PLAIN, 20));
    lbl_desc.setFont(new Font("Arial", Font.PLAIN, 20));
    lbl_accountcode.setFont(new Font("Arial", Font.PLAIN, 20));
    lbl_codetype.setFont(new Font("Arial", Font.PLAIN, 20));
    lbl_issuedate.setFont(new Font("Arial", Font.PLAIN, 20));
    lbl_amount.setFont(new Font("Arial", Font.PLAIN, 20));

    text_page = new JTextField(7);
    text_line = new JTextField(5);
    text_refpage = new JTextField(40);
    text_refline = new JTextField(40);
    text_transdate = new JTextField(10);
    text_desc = new JTextField(40);
    text_desc.addKeyListener(keycontrol);
    text_accountcode = new JTextField(5);
    text_codetype = new JTextField(5);
    text_issuedate = new JTextField(10);
    text_amount = new JTextField(20);


    text_page.setFont(new Font("Arial", Font.PLAIN, 20));
    text_line.setFont(new Font("Arial", Font.PLAIN, 20));
    text_refpage.setFont(new Font("Arial", Font.PLAIN, 20));
    text_refline.setFont(new Font("Arial", Font.PLAIN, 20));
    text_transdate.setFont(new Font("Arial", Font.PLAIN, 20));
    text_desc.setFont(new Font("Arial", Font.PLAIN, 20));
    text_accountcode.setFont(new Font("Arial", Font.PLAIN, 20));
    text_codetype.setFont(new Font("Arial", Font.PLAIN, 20));
    text_issuedate.setFont(new Font("Arial", Font.PLAIN, 20));
    text_amount.setFont(new Font("Arial", Font.PLAIN, 20));


    //text_desc.setEditable(false);

    //first row

    c.gridx = 0;
    c.gridy = 0;
    c.insets = new Insets(5,0,0,10);
    c.anchor = GridBagConstraints.LINE_END;
    add(lbl_page, c);

    c.gridx = 1;
    c.anchor = GridBagConstraints.LINE_START;
    add(text_page, c);

    //second row

    c.gridy++;

    c.anchor = GridBagConstraints.LINE_END;
    c.gridx=0;
    add(lbl_line, c);

    c.gridx = 1;
    c.anchor = GridBagConstraints.LINE_START;
    add(text_line, c);

    //third row

    c.gridy++;

    c.anchor = GridBagConstraints.LINE_END;
    c.gridx=0;
    add(lbl_refpage, c);

    c.gridx = 1;
    c.anchor = GridBagConstraints.LINE_START;
    add(text_refpage, c);

    //fourth row

    c.gridy++;

    c.anchor = GridBagConstraints.LINE_END;
    c.gridx=0;
    add(lbl_refline, c);

    c.gridx = 1;
    c.anchor = GridBagConstraints.LINE_START;
    add(text_refline, c);

    //fifth row

    c.gridy++;

    c.anchor = GridBagConstraints.LINE_END;
    c.gridx=0;
    add(lbl_transdate, c);

    c.gridx = 1;
    c.anchor = GridBagConstraints.LINE_START;
    add(text_transdate, c);

    //sixth row

    c.gridy++;

    c.anchor = GridBagConstraints.LINE_END;
    c.gridx=0;
    add(lbl_desc, c);

    c.gridx = 1;
    c.anchor = GridBagConstraints.LINE_START;
    add(text_desc, c);

    //seventh row

    c.gridy++;

    c.anchor = GridBagConstraints.LINE_END;
    c.gridx=0;
    add(lbl_accountcode, c);

    c.gridx = 1;
    c.anchor = GridBagConstraints.LINE_START;
    add(text_accountcode, c);

    //eighth row

    c.gridy++;

    c.anchor = GridBagConstraints.LINE_END;
    c.gridx=0;
    add(lbl_codetype, c);

    c.gridx = 1;
    c.anchor = GridBagConstraints.LINE_START;
    add(text_codetype, c);

    //ninth row

    c.gridy++;

    c.anchor = GridBagConstraints.LINE_END;
    c.gridx=0;
    add(lbl_issuedate, c);

    c.gridx = 1;
    c.anchor = GridBagConstraints.LINE_START;
    add(text_issuedate, c);

    //tenth row

    c.gridy++;

    c.anchor = GridBagConstraints.LINE_END;
    c.gridx=0;
    add(lbl_amount, c);

    c.gridx = 1;
    c.anchor = GridBagConstraints.LINE_START;
    add(text_amount, c);

    //tenth row

    c.gridy++;

    c.gridx = 1;
    c.anchor = GridBagConstraints.LINE_END;
    add(btn_testing, c);

}

class HandleControlButton implements ActionListener
{
    public void actionPerformed (ActionEvent e)
    {
        Object source = e.getSource();

        if(source == btn_testing)
        {
                text_desc.requestFocus();    
        }
    }
}

class HandleKeyListener implements KeyListener
{
    public void keyTyped(KeyEvent x)
    {
        System.out.println(x);
    }
}
}

---

我希望能够使用键盘上的向上或向下按钮将焦点从一个文本字段转移到下一个文本字段。

如注释中所述，错误意味着您必须从界面KeyListener实现所有方法。它有三种方法

• keyTyped（您已经实现的）
• 按键（未实现）
• 密钥已释放（未实现）

因此，您可以为这些方法添加一个空的实现，但在这种情况下，最简单的方法是扩展类，而不是实现KeyListener（因为KeyAdapter实现KeyListener，并且只实现了空的方法，这正是您在这里需要的）

因此，您可以将KeyListener类更改为：

class HandleKeyListener extends KeyAdapter {
    public void keyTyped(KeyEvent x) {
        System.out.println(x);
    }
}

---

然后它应该可以工作。

就像注释中提到的那样，错误意味着您必须从接口KeyListener实现所有方法。它有三种方法

• keyTyped（您已经实现的）
• 按键（未实现）
• 密钥已释放（未实现）

因此，您可以为这些方法添加一个空的实现，但在这种情况下，最简单的方法是扩展类，而不是实现KeyListener（因为KeyAdapter实现KeyListener，并且只实现了空的方法，这正是您在这里需要的）

因此，您可以将KeyListener类更改为：

class HandleKeyListener extends KeyAdapter {
    public void keyTyped(KeyEvent x) {
        System.out.println(x);
    }
}

---

那么它应该会起作用。

因此，实施您没有实施的方法。如果您实现了一个接口，而您的类不是抽象的，这意味着您必须提供该接口方法的实现。请实现您没有实现的方法。如果您实现了一个接口，而您的类不是抽象的，这意味着您必须提供该接口方法的实现Hanks我在缺少的方法中键入了hanks，它成功了。。也许我会试试KeyAdapter..谢谢，我输入了缺少的方法，它成功了。。也许我会试试键盘适配器。。