By default, one InputContext instance is created per Window instance, and this input context is shared by all components within the window's container hierarchy. However, this means that only one text input operation is possible at any one time within a window, and that the text needs to be committed when moving the focus from one text component to another. If this is not desired, text components can create their own input context instances.
The Java 2 platform supports input methods that have been developed in the Java programming language, using the interfaces in the java.awt.im.spi package, and installed into a Java 2 runtime environment as extensions. Implementations may also support using the native input methods of the platforms they run on; however, not all platforms and locales provide input methods. Keyboard layouts are provided by the host platform.
Input methods are unavailable if (a) no input method written in the Java programming language has been installed and (b) the Java 2 implementation or the underlying platform does not support native input methods. In this case, input contexts can still be created and used; their behavior is specified with the individual methods below.
A text editing component may call this in a variety of situations, for example, when the user moves the insertion point within the text (but outside the composed text), or when the component's text is saved to a file or copied to the clipboard.
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.
If no input methods are available or the current input method does not provide an input method control object, then null is returned.
Not all host operating systems provide API to determine the locale of
the currently selected native input method or keyboard layout.
For host operating systems that don't provide such API,
getLocale assumes that the current locale of all native
input methods or keyboard layouts provided by the host operating system
is the system's default locale.
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.
InputMethodRequests methods
must be prepared to deal with further information requests by
the input method. The composed and/or committed text will be
sent to the client component as a sequence of
InputMethodEvents. If the input method cannot
reconvert the given text, the text is returned as committed
text in an InputMethodEvent.
Not all host operating systems provide API to determine the locale of
the currently selected native input method or keyboard layout, and to
select a native input method or keyboard layout by locale.
For host operating systems that don't provide such API,
selectInputMethod assumes that native input methods or
keyboard layouts provided by the host operating system support only the
system's default locale.
A text editing component may call this method, for example, when the user changes the insertion point, so that the user can immediately continue typing in the language of the surrounding text.
enable.
An input method that is enabled for composition interprets incoming events for both composition and control purposes, while a disabled input method does not interpret events for composition. Note however that events are passed on to the input method regardless whether it is enabled or not, and that an input method that is disabled for composition may still interpret events for control purposes, including to enable or disable itself for composition.
For input methods provided by host operating systems, it is not always possible to determine whether this operation is supported. For example, an input method may enable composition only for some locales, and do nothing for other locales. For such input methods, it is possible that this method does not throw UnsupportedOperationException , but also does not affect whether composition is enabled.
toString method returns a string that
"textually represents" this object. The result should
be a concise but informative representation that is easy for a
person to read.
It is recommended that all subclasses override this method.
The toString method for class Object
returns a string consisting of the name of the class of which the
object is an instance, the at-sign character `@', and
the unsigned hexadecimal representation of the hash code of the
object. In other words, this method returns a string equal to the
value of:
getClass().getName() + '@' + Integer.toHexString(hashCode())
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.