With this example we shall show you how to set the component that gets the focus when your application starts up. This is very useful when you have many graphical objects firing up at the start up of your application.
Let’s see the code snippet that follows and it should be pretty clear:
package com.javacodegeeks.snippets.desktop;
import java.awt.BorderLayout;
import java.awt.Button;
import java.awt.Component;
import java.awt.Frame;
import java.awt.TextArea;
import java.awt.Window;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
public class InitialFocusGain {
public static void main(String[] args) {
// Create frame with specific title
Frame frame = new Frame("Example Frame");
// Create a component to add to the frame; in this case a text area with sample text
Component textArea = new TextArea("Sample text...");
// Create a component to add to the frame; in this case a button
Component button = new Button("Click Me!!");
// Add the components to the frame; by default, the frame has a border layout
frame.add(textArea, BorderLayout.NORTH);
frame.add(button, BorderLayout.SOUTH);
// Set component with initial focus; must be done before the frame is made visible
InitialFocusSetter.setInitialFocus(frame, button);
// Show the frame
int width = 300;
int height = 300;
frame.setSize(width, height);
frame.setVisible(true);
}
static class InitialFocusSetter {
public static void setInitialFocus(Window w, Component c) {
w.addWindowListener(new FocusSetter(c));
}
public static class FocusSetter extends WindowAdapter {
Component initialComponent;
FocusSetter(Component c) {
initialComponent = c;
}
public void windowOpened(WindowEvent e) {
initialComponent.requestFocus();
// This listener is no longer needed so we remove it
e.getWindow().removeWindowListener(this);
}
}
}
}
This was an example on how to set the initial focus component in a Window.
