Question

我希望能够在我的框架带来前景时输入文本字段。程序设置为在5秒后将我的帧置于前景并将焦点设置在文本字段上。我启动程序然后单击另一个窗口。光标闪烁后，我的画面在5秒后显示。但是当我输入某些东西时，它实际上并没有被textfield作为输入。我还实现了FocusListener，以确认当帧到达前景时焦点设置为textfield。我的操作系统是Windows 10。

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class TestMain implements FocusListener {
    /**
     * Create the GUI and show it. For thread safety, this method should be
     * invoked from the event-dispatching thread.
     */
    public JFrame frame = null;

    private void createAndShowGUI() {
        // Create and set up the window.
        frame = new JFrame();
        frame.addFocusListener(this);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JPanel panel = new JPanel();
        panel.setLayout(new FlowLayout());

        JLabel label1 = new JLabel("Label");
        panel.add(label1);

        JTextField textField1 = new JTextField();
        textField1.setPreferredSize(new Dimension(300, 40));
        panel.add(textField1);
        textField1.addFocusListener(this);
        label1.addFocusListener(this);

        frame.addWindowListener(new WindowAdapter() {
            // Program Closing Alert
            public void windowActivated(WindowEvent e) {
                System.out.println("window activated");
                textField1.requestFocusInWindow();
            }
        });

        frame.getContentPane().add(panel, BorderLayout.CENTER);

        // Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        TestMain mn = null;
        // Schedule a job for the event-dispatching thread:
        // creating and showing this application's GUI.
        mn = new TestMain();
        mn.createAndShowGUI();

        System.out.println("START");
        try {
            Thread.sleep(5000);
            mn.frame.setAlwaysOnTop(true);

        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    @Override
    public void focusGained(FocusEvent e) {
        System.out.println("Focus Gained by " + e.getComponent().getClass().getName());

    }

    @Override
    public void focusLost(FocusEvent e) {
        System.out.println("Focus Lost by " + e.getComponent().getClass().getName());

    }

}

更新：当我添加

时

frame.setLocationByPlatform( true );

之后

 frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

它仅适用于第一次。如果我改变主要功能

try {
    Thread.sleep(5000);
    mn.frame.setAlwaysOnTop(true);
    mn.frame.setAlwaysOnTop(false);
    Thread.sleep(5000);
    mn.frame.setAlwaysOnTop(true);
    mn.frame.setAlwaysOnTop(false);
} catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

它第二次不起作用

Answer 1

您确实将焦点带到了JTextField，但是您不会将焦点对准帧本身。将框架放在前面并将焦点带到框架上是不同的。可以在此处找到类似的解决方案：How to set focus the already running application?

Answer 2

移动框架不会聚焦文本字段。您应该在始终设置在顶部之后添加toFront()，这样如果窗口可见，则将窗口置于前面并使其成为焦点窗口。

try {
    Thread.sleep(5000);
    mn.frame.setVisible ( true );
    mn.frame.toFront ( );

} catch (InterruptedException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

Java将窗口带到前面并不允许我输入文本字段

2 个答案: