Java Gui get.Text();不工作

Question

我得到了下面的代码来获取文本，但我有一个问题。它给我一个错误，说它无法解决。我是 java gui 的新手。希望可以有人帮帮我。我尝试使用 nameP.getText();，但没有成功。我不确定为什么会出现错误？

 private class createListener implements ActionListener{
    public void actionPerformed(ActionEvent event){

            JFrame frame = new JFrame("Create Player");
            JPanel panel = new JPanel();
            JPanel mainpanel = new JPanel();
            JButton create;
            JLabel welcome = new JLabel("Create Player");
            JLabel name = new JLabel("Enter Player Name");
            JTextField nameP = new JTextField();
            JLabel pass = new JLabel("Enter Player Password");
            JTextField passwd = new JTextField();
            JLabel chips = new JLabel("Enter Player Chips");
            JTextField chipsP = new JTextField();
            buttonCreate = new JButton("Create Player");

            setSize(400,350);
            setLocation(500,280);
            panel.setLayout(new GridLayout(0,1,10,10));

            panel.add(name);
            panel.add(nameP);
            panel.add(pass);
            panel.add(passwd);
            panel.add(chips);
            panel.add(chipsP);
            panel.add(buttonCreate);
            mainpanel.add(panel);

            getContentPane().removeAll();
            getContentPane().add(mainpanel);
            setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            setVisible(true);
            buttonCreate.addActionListener(new createListener());
        }

    }
    private class playerListener implements ActionListener{
    public void actionPerformed(ActionEvent event){
        String name = nameP.getText();

    }
}

Answer 1

nameP 变量是本地，因此您无法在 actionPerformed 之外、该范围之外引用它nameP 不存在。您可以将其声明为 class member如果您想在其他地方使用它，则可以使用变量。

JTextField nameP;

    private class createListener implements ActionListener{
      public void actionPerformed(ActionEvent event){
        nameP = new JTextField();
      }
    }

    private class playerListener implements ActionListener{
      public void actionPerformed(ActionEvent event){
        String name = nameP.getText();
    }