e606. Determining Which Component or Window Has the Focus

    // null is returned if none of the components in this application has the focus
    Component compFocusOwner =
        KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusOwner();
    
    // null is returned if none of the windows in this application has the focus
    Window windowFocusOwner =
        KeyboardFocusManager.getCurrentKeyboardFocusManager().getFocusedWindow();
    
    // Use this method to determine whether a particular component has the focus
    boolean b = component.isFocusOwner();

e606. Determining Which Component or Window Has the Focus

原文：https://www.cnblogs.com/borter/p/9596084.html