Question

我有一个简单的登录屏幕。我希望UserName和Password显示在第一个和第二个文本字段中，直到它们被单击为止。此功能正常运行。但是，第一个文本字段始终在应用程序启动时聚焦，因此显示为“”，直到它失去焦点。我试图设置一个默认按钮，请求焦点无济于事。看起来按钮正确默认，但由于某种原因它没有获得焦点。任何人都知道如何解决这个问题？

public class Basics implements ActionListener{

private JFrame frmBasics;
private JTextField userNameFeild;
private JTextField passwordFeild;
private JButton btnSignIn;
private JButton btnSignUp;

/**
 * Launch the application.
 */
public static void main(String[] args) {



    EventQueue.invokeLater(new Runnable() {
        public void run() {
            try {
                Basics window = new Basics();
                window.frmBasics.setVisible(true);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    });


}//end main

/**
 * Create the application.
 */
public Basics() {
    initialize();
}

/**
 * Initialize the contents of the frame.
 */
private void initialize() {
    frmBasics = new JFrame();
    frmBasics.setTitle("Welcome to the POOPalace!!!");
    frmBasics.setBounds(100, 100, 511, 344);
    frmBasics.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frmBasics.getContentPane().setLayout(null);

    userNameFeild = new JTextField("UserName");
    userNameFeild.setBounds(148, 79, 214, 20);
    userNameFeild.addFocusListener(new FocusedClass());
    frmBasics.getContentPane().add(userNameFeild);
    userNameFeild.setColumns(10);

    passwordFeild = new JTextField("Password");
    passwordFeild.setBounds(148, 126, 214, 20);
    passwordFeild.addFocusListener(new FocusedClass());
    frmBasics.getContentPane().add(passwordFeild);
    passwordFeild.setColumns(10);

    btnSignIn = new JButton("Sign In");
    btnSignIn.setBounds(148, 182, 89, 23);
    btnSignIn.addActionListener(this);
    frmBasics.getContentPane().add(btnSignIn);

    btnSignUp = new JButton("Sign Up");
    btnSignUp.setBounds(273, 182, 89, 23);
    btnSignUp.addActionListener(this);
    frmBasics.getContentPane().add(btnSignUp);

    //from what I've been reading these 2 lines should be the solution
    //but the request focus seems to not be working 
    frmBasics.getRootPane().setDefaultButton(btnSignIn);;
    btnSignIn.requestFocus();


}

@Override
public void actionPerformed(ActionEvent e) {

    //frmBasics.getContentPane().removeAll();
    //frmBasics.repaint();
    System.out.println(userNameFeild.getText());
    System.out.println(passwordFeild.getText());

}//actionPerformed


private class FocusedClass implements FocusListener {

    @Override
    public void focusGained(FocusEvent arg0) {

        if(arg0.getSource().equals(userNameFeild) && userNameFeild.getText().compareTo("UserName") == 0){
            userNameFeild.setText("");
            }
        if(arg0.getSource().equals(passwordFeild) && passwordFeild.getText().compareTo("Password") == 0){
            passwordFeild.setText("");
        }

    }

    @Override
    public void focusLost(FocusEvent arg0) {

        if(userNameFeild.getText().compareTo("") == 0){
            userNameFeild.setText("UserName");
        }

        if(passwordFeild.getText().compareTo("") == 0){
            passwordFeild.setText("Password");
        }

        frmBasics.getContentPane().repaint();
    }

}



}//class

Answer 1

请求焦点仅在窗口布局完成后才起作用。我们需要在三种特定情况之一中调用requestFocusInWindow()：

在windowOpened()方法中。
在EventQueue's invokeLater()中，将在处理完所有待处理事件后运行。
在覆盖JFrame's setVisible()方法中。

第一个选项：

//btnSignIn.requestFocusInWindow();

frmBasics.addWindowListener(new WindowAdapter() {
    @Override
    public void windowOpened(WindowEvent e) {
        btnSignIn.requestFocusInWindow();
    }
});

另请注意，requestFocusInWindow()比requestFocus()更便携 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %> <!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head runat="server"> <title></title> <style type="text/css"> .notification { background-color:#006699; min-height:40px; width:30%; margin:0 auto; text-align:center; line-height:50px; color:#fff; font-size:18px; box-shadow: 10px 10px 5px #888888; } </style> <script src="google.min.js" type="text/javascript"></script> <script language="javascript" type="text/javascript"> $(document).ready(function () { $(".btn1").click(function () { $("#dvMsg").fadeOut(5000, 0, 0); }); }); </script> </head> <body> <form id="form1"> <div id="dvMsg" class="notification" runat="server" visible="true"> <asp:Label ID="lblMsg" runat="server" Text="This is just "></asp:Label> </div> <button class="btn1">Fade out</button> </form> </body> </html>。

无法停止JTextFeild获取默认焦点

1 个答案: