WindowFocusListener (Java SE 11 & JDK 11 )

All Superinterfaces:

EventListener

All Known Implementing Classes:

AWTEventMulticaster, BasicToolBarUI.FrameListener, JMenu.WinListener, WindowAdapter
```
public interface WindowFocusListener
extends EventListener
```
The listener interface for receiving WindowEvents, including WINDOW_GAINED_FOCUS and WINDOW_LOST_FOCUS events. The class that is interested in processing a WindowEvent either implements this interface (and all the methods it contains) or extends the abstract WindowAdapter class (overriding only the methods of interest). The listener object created from that class is then registered with a Window using the Window's addWindowFocusListener method. When the Window's status changes by virtue of it being opened, closed, activated, deactivated, iconified, or deiconified, or by focus being transferred into or out of the Window, the relevant method in the listener object is invoked, and the WindowEvent is passed to it.

Since:

1.4

See Also:

WindowAdapter, WindowEvent, Tutorial: Writing a Window Listener

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`windowGainedFocus(WindowEvent e)`	Invoked when the Window is set to be the focused Window, which means that the Window, or one of its subcomponents, will receive keyboard events.
`void`	`windowLostFocus(WindowEvent e)`	Invoked when the Window is no longer the focused Window, which means that keyboard events will no longer be delivered to the Window or any of its subcomponents.

- Method Detail
  - windowGainedFocus
```
void windowGainedFocus(WindowEvent e)
```
    Invoked when the Window is set to be the focused Window, which means that the Window, or one of its subcomponents, will receive keyboard events.
    
    Parameters:
    
    e - the event to be processed
  - windowLostFocus
```
void windowLostFocus(WindowEvent e)
```
    Invoked when the Window is no longer the focused Window, which means that keyboard events will no longer be delivered to the Window or any of its subcomponents.
    
    Parameters:
    
    e - the event to be processed