Java Reference
In-Depth Information
extends MenuItem to create arbitrarily complex menus.) Menu is subclassed
by PopupMenu to describe a menu that can be dynamically popped up at a
specified position within a component.
Component declares many nonmenu component-oriented methods. For example,
Component declaresthefollowingmethodstoinformthecalleraboutthecomponent's
displayable, visible, and showing status:
boolean isDisplayable() returnstruewhenacomponentisinthe dis-
playable state (thecomponentisconnectedtoanativescreenresource[defined
shortly], typically by being added to a container).
boolean isVisible() returns true when a component is in the visible
state (thecomponentappearsonthescreen).Thecompanion void setVis-
ible(boolean b) methodletsyoushow( b is true )orhide( b is false )
a component.
boolean isShowing() returns true when a component is in the showing
state (thecomponentisvisibleandiscontainedinacontainerthatisalsovisible
ent has been obscured by another component. It returns false when obscured,
whereas isVisible() would continue to return true.
MenuComponent 'srepertoireofmethodsismuchshorter.However,itsharessome
commonality with Component . For example, both classes declare a method for spe-
cifying the component's font.
Some of Component 's and MenuComponent 's methods have been deprecated
and should not be used. For example, Component declares
java.awt.peer.ComponentPeer getPeer() and MenuComponent de-
clares java.awt.peer.MenuComponentPeer getPeer() . Both deprecated
methods hint at how AWT implements its predefined components.
AWT leverages the platform's windowing system to create various components.
plementsa ComponentPeer or MenuComponentPeer subinterface.Forexample,
AWT creates a java.awt.peer.ButtonPeer instance when you add a Button
component class instance to a container.
Note Each AWT toolkit implementation includes its own set of peer interface im-
Behind the scenes, the component object communicates with the peer object, which
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