Component
hierarchy to which a Component belongs.
Hierarchy events are provided for notification purposes ONLY. The AWT will automatically handle changes to the hierarchy internally so that GUI layout and displayability works properly regardless of whether a program is receiving these events or not.
This event is generated by a Container object (such as a Panel) when the
Container is added, removed, moved, or resized, and passed down the
hierarchy. It is also generated by a Component object when that object's
addNotify, removeNotify, show, or
hide method is called. ANCESTOR_MOVED and ANCESTOR_RESIZED
events are dispatched to every HierarchyBoundsListener or
HierarchyBoundsAdapter object which registered to receive
such events using the Component's addHierarchyBoundsListener
method. (HierarchyBoundsAdapter objects implement the
HierarchyBoundsListener interface.) HIERARCHY_CHANGED events are
dispatched to every HierarchyListener object which registered
to receive such events using the Component's addHierarchyListener
method. Each such listener object gets this HierarchyEvent
when the event occurs.
HierarchyEvent object to identify a
change in the Component hierarchy.
Note that passing in an invalid id results in
unspecified behavior. This method throws an
IllegalArgumentException if source
is null.
HierarchyEvent object to identify
a change in the Component hierarchy.
Note that passing in an invalid id results in
unspecified behavior. This method throws an
IllegalArgumentException if source
is null.
HIERARCHY_CHANGED event
was generated due to a change in the displayability
of the hierarchy. To discern the
current displayability of the hierarchy, call
Component.isDisplayable. Displayability changes occur
in response to explicit or implicit calls to
Component.addNotify and
Component.removeNotify.HIERARCHY_CHANGED event
was generated by a reparenting operation.HIERARCHY_CHANGED event
was generated due to a change in the showing state
of the hierarchy. To discern the
current showing state of the hierarchy, call
Component.isShowing. Showing state changes occur
when either the displayability or visibility of the
hierarchy occurs. Visibility changes occur in response to explicit
or implicit calls to Component.show and
Component.hide.
The equals method implements an equivalence relation
on non-null object references:
x, x.equals(x) should return
true.
x and y, x.equals(y)
should return true if and only if
y.equals(x) returns true.
x, y, and z, if
x.equals(y) returns true and
y.equals(z) returns true, then
x.equals(z) should return true.
x and y, multiple invocations of
x.equals(y) consistently return true
or consistently return false, provided no
information used in equals comparisons on the
objects is modified.
x,
x.equals(null) should return false.
The equals method for class Object implements
the most discriminating possible equivalence relation on objects;
that is, for any non-null reference values x and
y, this method returns true if and only
if x and y refer to the same object
(x == y has the value true).
Note that it is generally necessary to override the hashCode method whenever this method is overridden, so as to maintain the general contract for the hashCode method, which states that equal objects must have equal hash codes.
getChanged(). For a HIERARCHY_CHANGED event where the
change was of type PARENT_CHANGED via a call to
Container.add, the parent returned is the parent
after the add operation. For a HIERARCHY_CHANGED event where
the change was of type PARENT_CHANGED via a call to
Container.remove, the parent returned is the parent
before the remove operation. For all other events and types,
the parent returned is the parent during the operation.java.util.Hashtable.
The general contract of hashCode is:
hashCode method on each of
the two objects must produce the same integer result.
As much as is reasonably practical, the hashCode method defined by class Object does return distinct integers for distinct objects. (This is typically implemented by converting the internal address of the object into an integer, but this implementation technique is not required by the JavaTM programming language.)
wait methods.
The awakened thread will not be able to proceed until the current thread relinquishes the lock on this object. The awakened thread will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened thread enjoys no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner of this object's monitor. A thread becomes the owner of the object's monitor in one of three ways:
synchronized statement
that synchronizes on the object.
Class, by executing a
synchronized static method of that class.
Only one thread at a time can own an object's monitor.
wait methods.
The awakened threads will not be able to proceed until the current thread relinquishes the lock on this object. The awakened threads will compete in the usual manner with any other threads that might be actively competing to synchronize on this object; for example, the awakened threads enjoy no reliable privilege or disadvantage in being the next thread to lock this object.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
This method is intended to be used only by event targeting subsystems, such as client-defined KeyboardFocusManagers. It is not for general client use.
The current thread must own this object's monitor. The thread
releases ownership of this monitor and waits until another thread
notifies threads waiting on this object's monitor to wake up
either through a call to the notify method or the
notifyAll method. The thread then waits until it can
re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait();
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.The current thread must own this object's monitor.
This method causes the current thread (call it T) to place itself in the wait set for this object and then to relinquish any and all synchronization claims on this object. Thread T becomes disabled for thread scheduling purposes and lies dormant until one of four things happens:
A thread can also wake up without being notified, interrupted, or timing out, a so-called spurious wakeup. While this will rarely occur in practice, applications must guard against it by testing for the condition that should have caused the thread to be awakened, and continuing to wait if the condition is not satisfied. In other words, waits should always occur in loops, like this one:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout);
... // Perform action appropriate to condition
}
(For more information on this topic, see Section 3.2.3 in Doug Lea's
"Concurrent Programming in Java (Second Edition)" (Addison-Wesley,
2000), or Item 50 in Joshua Bloch's "Effective Java Programming
Language Guide" (Addison-Wesley, 2001).
If the current thread is interrupted by another thread while it is waiting, then an InterruptedException is thrown. This exception is not thrown until the lock status of this object has been restored as described above.
Note that the wait method, as it places the current thread into the wait set for this object, unlocks only this object; any other objects on which the current thread may be synchronized remain locked while the thread waits.
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.
This method is similar to the wait method of one
argument, but it allows finer control over the amount of time to
wait for a notification before giving up. The amount of real time,
measured in nanoseconds, is given by:
1000000*timeout+nanos
In all other respects, this method does the same thing as the method of one argument. In particular, wait(0, 0) means the same thing as wait(0).
The current thread must own this object's monitor. The thread releases ownership of this monitor and waits until either of the following two conditions has occurred:
notify method
or the notifyAll method.
timeout
milliseconds plus nanos nanoseconds arguments, has
elapsed.
The thread then waits until it can re-obtain ownership of the monitor and resumes execution.
As in the one argument version, interrupts and spurious wakeups are possible, and this method should always be used in a loop:
synchronized (obj) {
while (<condition does not hold>)
obj.wait(timeout, nanos);
... // Perform action appropriate to condition
}
This method should only be called by a thread that is the owner
of this object's monitor. See the notify method for a
description of the ways in which a thread can become the owner of
a monitor.