ImageReader
objects are normally instantiated by
the service provider interface (SPI) class for the specific format.
Service provider classes (e.g., instances of
ImageReaderSpi
) are registered with the
IIORegistry
, which uses them for format recognition
and presentation of available format readers and writers.
When an input source is set (using the setInput
method), it may be marked as "seek forward only". This setting
means that images contained within the input source will only be
read in order, possibly allowing the reader to avoid caching
portions of the input containing data associated with images that
have been read previously.
Readers should call clearAbortRequest
at the
beginning of each read operation, and poll the value of
abortRequested
regularly during the read.
IIOReadProgressListener
to the list of
registered progress listeners. If listener
is
null
, no exception will be thrown and no action
will be taken.IIOReadUpdateListener
to the list of
registered update listeners. If listener
is
null
, no exception will be thrown and no action
will be taken. The listener will receive notification of pixel
updates as images and thumbnails are decoded, including the
starts and ends of progressive passes.
If no update listeners are present, the reader may choose to perform fewer updates to the pixels of the destination images and/or thumbnails, which may result in more efficient decoding.
For example, in progressive JPEG decoding each pass contains updates to a set of coefficients, which would have to be transformed into pixel values and converted to an RGB color space for each pass if listeners are present. If no listeners are present, the coefficients may simply be accumulated and the final results transformed and color converted one time only.
The final results of decoding will be the same whether or
not intermediate updates are performed. Thus if only the final
image is desired it may be perferable not to register any
IIOReadUpdateListener
s. In general, progressive
updating is most effective when fetching images over a network
connection that is very slow compared to local CPU processing;
over a fast connection, progressive updates may actually slow
down the presentation of the image.
IIOReadWarningListener
to the list of
registered warning listeners. If listener
is
null
, no exception will be thrown and no action
will be taken. Messages sent to the given listener will be
localized, if possible, to match the current
Locale
. If no Locale
has been set,
warning messages may be localized as the reader sees fit.true
if this plug-in supports reading
just a Raster
of pixel data.
If this method returns false
, calls to
readRaster
or readTileRaster
will throw an
UnsupportedOperationException
.
The default implementation returns false
.
finalize
) subsequent to a call to this method
is undefined.
It is important for applications to call this method when they
know they will no longer be using this ImageReader
.
Otherwise, the reader may continue to hold on to resources
indefinitely.
The default implementation of this method in the superclass does nothing. Subclass implementations should ensure that all resources, especially native resources, are released.
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.
float
. For images
that are inherently resizable, this method provides a way to
determine the appropriate width given a deired height, or vice
versa. For non-resizable images, the true width and height
are used.
The default implementation simply returns
(float)getWidth(imageIndex)/getHeight(imageIndex)
.
Locale
s that may be used to
localize warning listeners and compression settings. A return
value of null
indicates that localization is not
supported.
The default implementation returns a clone of the
availableLocales
instance variable if it is
non-null
, or else returns null
.
ImageReadParam
object
appropriate for this format. All subclasses should define a
set of default values for all parameters and return them with
this call. This method may be called before the input source
is set.
The default implementation constructs and returns a new
ImageReadParam
object that does not allow source
scaling (i.e., it returns new
ImageReadParam()
.
String
identifying the format of the
input source.
The default implementation returns
originatingProvider.getFormatNames()[0]
.
Implementations that may not have an originating service
provider, or which desire a different naming policy should
override this method.
If the image can be rendered to a user-specified size, then this method returns the default height.
IIOMetadata
object containing metadata
associated with the given image, or null
if the
reader does not support reading metadata, is set to ignore
metadata, or if no metadata is available.IIOMetadata
object representing the
metadata associated with the given image, or null
if the reader does not support reading metadata or none
is available.
The resuting metadata object is only responsible for
returning documents in the format named by
formatName
. Within any documents that are
returned, only nodes whose names are members of
nodeNames
are required to be returned. In this
way, the amount of metadata processing done by the reader may
be kept to a minimum, based on what information is actually
needed.
If formatName
is not the name of a supported
metadata format, null
may be returned.
In all cases, it is legal to return a more capable metadata object than strictly necessary. The format name and node names are merely hints that may be used to reduce the reader's workload.
The default implementation simply returns the result of
calling getImageMetadata(imageIndex)
, after
checking that the format name is supported. If it is not,
null
is returned.
Iterator
containing possible image
types to which the given image may be decoded, in the form of
ImageTypeSpecifiers
s. At least one legal image
type will be returned.
The first element of the iterator should be the most "natural" type for decoding the image with as little loss as possible. For example, for a JPEG image the first entry should be an RGB image, even though the image data is stored internally in a YCbCr color space.
ImageInputStream
or other
Object
previously set as the input source. If the
input source has not been set, null
is returned.Locale
, or
null
if none has been set.seekForwardOnly()
is
false
, this value will typically remain 0,
indicating that random access is possible. Otherwise, it will
contain the value of the most recently accessed index, and
increase in a monotonic fashion. Note that some image formats (such as animated GIF) do not
specify how many images are present in the stream. Thus
determining the number of images will require the entire stream
to be scanned and may require memory for buffering. If images
are to be processed in order, it may be more efficient to
simply call read
with increasing indices until an
IndexOutOfBoundsException
is thrown to indicate
that no more images are available. The
allowSearch
parameter may be set to
false
to indicate that an exhaustive search is not
desired; the return value will be -1
to indicate
that a search is necessary. If the input has been specified
with seekForwardOnly
set to true
,
this method throws an IllegalStateException
if
allowSearch
is set to true
.
readerSupportsThumbnails
returns
false
), 0
will be returned regardless
of whether an input source has been set or whether
imageIndex
is in bounds.
The default implementation returns 0 without checking its argument.
ImageReaderSpi
that was passed in on
the constructor. Note that this value may be null
.ImageTypeSpecifier
indicating the
SampleModel
and ColorModel
which most
closely represents the "raw" internal format of the image. For
example, for a JPEG image the raw type might have a YCbCr color
space even though the image would conventionally be transformed
into an RGB color space prior to display. The returned value
should also be included in the list of values returned by
getImageTypes
.
The default implementation simply returns the first entry
from the list provided by getImageType
.
IIOMetadata
object representing the
metadata associated with the input source as a whole (i.e., not
associated with any particular image), or null
if
the reader does not support reading metadata, is set to ignore
metadata, or if no metadata is available.IIOMetadata
object representing the
metadata associated with the input source as a whole (i.e.,
not associated with any particular image). If no such data
exists, null
is returned.
The resuting metadata object is only responsible for
returning documents in the format named by
formatName
. Within any documents that are
returned, only nodes whose names are members of
nodeNames
are required to be returned. In this
way, the amount of metadata processing done by the reader may
be kept to a minimum, based on what information is actually
needed.
If formatName
is not the name of a supported
metadata format, null
is returned.
In all cases, it is legal to return a more capable metadata object than strictly necessary. The format name and node names are merely hints that may be used to reduce the reader's workload.
The default implementation simply returns the result of
calling getStreamMetadata()
, after checking that
the format name is supported. If it is not,
null
is returned.
thumbnailIndex
, associated with the image indexed
by ImageIndex
.
If the reader does not support thumbnails,
(readerSupportsThumbnails
returns
false
), an UnsupportedOperationException
will be thrown.
The default implementation simply returns
readThumbnail(imageindex,
thumbnailIndex).getHeight()
. Subclasses should
therefore override this method if possible in order to avoid
forcing the thumbnail to be read.
thumbnailIndex
, associated with the image indexed
by ImageIndex
.
If the reader does not support thumbnails,
(readerSupportsThumbnails
returns
false
), an UnsupportedOperationException
will be thrown.
The default implementation simply returns
readThumbnail(imageindex,
thumbnailIndex).getWidth()
. Subclasses should therefore
override this method if possible in order to avoid forcing the
thumbnail to be read.
A reader for which the tile grid X offset always has the same value (usually 0), may return the value without accessing any image data. In such cases, it is not necessary to throw an exception even if no input source has been set or the image index is out of bounds.
The default implementation simply returns 0, which is correct for non-tiled images and tiled images in most formats. Readers that support tiling with non-(0, 0) offsets should override this method.
A reader for which the tile grid Y offset always has the same value (usually 0), may return the value without accessing any image data. In such cases, it is not necessary to throw an exception even if no input source has been set or the image index is out of bounds.
The default implementation simply returns 0, which is correct for non-tiled images and tiled images in most formats. Readers that support tiling with non-(0, 0) offsets should override this method.
The default implementation simply returns
getHeight(imageIndex)
, which is correct for
non-tiled images. Readers that support tiling should override
this method.
The default implementation simply returns
getWidth(imageIndex)
, which is correct for
non-tiled images. Readers that support tiling should override
this method.
If the image can be rendered to a user-specified size, then this method returns the default width.
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.)
true
if the given image has thumbnail
preview images associated with it. If the format does not
support thumbnails (readerSupportsThumbnails
returns false
), false
will be
returned regardless of whether an input source has been set or
whether imageIndex
is in bounds.
The default implementation returns true
if
getNumThumbnails
returns a value greater than 0.
true
if the current input source has been
marked as allowing metadata to be ignored by passing
true
as the ignoreMetadata
argument
to the setInput
method.true
if the image is organized into
tiles, that is, equal-sized non-overlapping rectangles.
A reader plug-in may choose whether or not to expose tiling
that is present in the image as it is stored. It may even
choose to advertise tiling when none is explicitly present. In
general, tiling should only be advertised if there is some
advantage (in speed or space) to accessing individual tiles.
Regardless of whether the reader advertises tiling, it must be
capable of reading an arbitrary rectangular region specified in
an ImageReadParam
.
A reader for which all images are guaranteed to be tiled,
or are guaranteed not to be tiled, may return true
or false
respectively without accessing any image
data. In such cases, it is not necessary to throw an exception
even if no input source has been set or the image index is out
of bounds.
The default implementation just returns false
.
true
if the storage format of the given
image places no inherent impediment on random access to pixels.
For most compressed formats, such as JPEG, this method should
return false
, as a large section of the image in
addition to the region of interest may need to be decoded.
This is merely a hint for programs that wish to be
efficient; all readers must be able to read arbitrary regions
as specified in an ImageReadParam
.
Note that formats that return false
from
this method may nonetheless allow tiling (e.g. Restart
Markers in JPEG), and random access will likely be reasonably
efficient on tiles. See
isImageTiled
.
A reader for which all images are guaranteed to support
easy random access, or are guaranteed not to support easy
random access, may return true
or
false
respectively without accessing any image
data. In such cases, it is not necessary to throw an exception
even if no input source has been set or the image index is out
of bounds.
The default implementation returns false
.
true
if the current input source has been
marked as seek forward only by passing true
as the
seekForwardOnly
argument to the
setInput
method.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.
imageIndex
and returns
it as a complete BufferedImage
, using a default
ImageReadParam
. This is a convenience method
that calls read(imageIndex, null)
.
The image returned will be formatted according to the first
ImageTypeSpecifier
returned from
getImageTypes
.
Any registered IIOReadProgressListener
objects
will be notified by calling their imageStarted
method, followed by calls to their imageProgress
method as the read progresses. Finally their
imageComplete
method will be called.
IIOReadUpdateListener
objects may be updated at
other times during the read as pixels are decoded. Finally,
IIOReadWarningListener
objects will receive
notification of any non-fatal warnings that occur during
decoding.
imageIndex
and returns
it as a complete BufferedImage
, using a supplied
ImageReadParam
.
The actual BufferedImage
returned will be
chosen using the algorithm defined by the
getDestination
method.
Any registered IIOReadProgressListener
objects
will be notified by calling their imageStarted
method, followed by calls to their imageProgress
method as the read progresses. Finally their
imageComplete
method will be called.
IIOReadUpdateListener
objects may be updated at
other times during the read as pixels are decoded. Finally,
IIOReadWarningListener
objects will receive
notification of any non-fatal warnings that occur during
decoding.
The set of source bands to be read and destination bands to
be written is determined by calling getSourceBands
and getDestinationBands
on the supplied
ImageReadParam
. If the lengths of the arrays
returned by these methods differ, the set of source bands
contains an index larger that the largest available source
index, or the set of destination bands contains an index larger
than the largest legal destination index, an
IllegalArgumentException
is thrown.
If the supplied ImageReadParam
contains
optional setting values not supported by this reader (e.g.
source render size or any format-specific settings), they will
be ignored.
imageIndex
and returns
an IIOImage
containing the image, thumbnails, and
associated image metadata, using a supplied
ImageReadParam
.
The actual BufferedImage
referenced by the
returned IIOImage
will be chosen using the
algorithm defined by the getDestination
method.
Any registered IIOReadProgressListener
objects
will be notified by calling their imageStarted
method, followed by calls to their imageProgress
method as the read progresses. Finally their
imageComplete
method will be called.
IIOReadUpdateListener
objects may be updated at
other times during the read as pixels are decoded. Finally,
IIOReadWarningListener
objects will receive
notification of any non-fatal warnings that occur during
decoding.
The set of source bands to be read and destination bands to
be written is determined by calling getSourceBands
and getDestinationBands
on the supplied
ImageReadParam
. If the lengths of the arrays
returned by these methods differ, the set of source bands
contains an index larger that the largest available source
index, or the set of destination bands contains an index larger
than the largest legal destination index, an
IllegalArgumentException
is thrown.
Thumbnails will be returned in their entirety regardless of the region settings.
If the supplied ImageReadParam
contains
optional setting values not supported by this reader (e.g.
source render size or any format-specific settings), those
values will be ignored.
Iterator
containing all the images,
thumbnails, and metadata, starting at the index given by
getMinIndex
, from the input source in the form of
IIOImage
objects. An Iterator
containing ImageReadParam
objects is supplied; one
element is consumed for each image read from the input source
until no more images are available. If the read param
Iterator
runs out of elements, but there are still
more images available from the input source, default read
params are used for the remaining images.
If params
is null
, a default read
param will be used for all images.
The actual BufferedImage
referenced by the
returned IIOImage
will be chosen using the
algorithm defined by the getDestination
method.
Any registered IIOReadProgressListener
objects
will be notified by calling their sequenceStarted
method once. Then, for each image decoded, there will be a
call to imageStarted
, followed by calls to
imageProgress
as the read progresses, and finally
to imageComplete
. The
sequenceComplete
method will be called after the
last image has been decoded.
IIOReadUpdateListener
objects may be updated at
other times during the read as pixels are decoded. Finally,
IIOReadWarningListener
objects will receive
notification of any non-fatal warnings that occur during
decoding.
The set of source bands to be read and destination bands to
be written is determined by calling getSourceBands
and getDestinationBands
on the supplied
ImageReadParam
. If the lengths of the arrays
returned by these methods differ, the set of source bands
contains an index larger that the largest available source
index, or the set of destination bands contains an index larger
than the largest legal destination index, an
IllegalArgumentException
is thrown.
Thumbnails will be returned in their entirety regardless of the region settings.
If any of the supplied ImageReadParam
s contain
optional setting values not supported by this reader (e.g.
source render size or any format-specific settings), they will
be ignored.
RenderedImage
object that contains the
contents of the image indexed by imageIndex
. By
default, the returned image is simply the
BufferedImage
returned by read(imageIndex,
param)
.
The semantics of this method may differ from those of the
other read
methods in several ways. First, any
destination image and/or image type set in the
ImageReadParam
may be ignored. Second, the usual
listener calls are not guaranteed to be made, or to be
meaningful if they are. This is because the returned image may
not be fully populated with pixel data at the time it is
returned, or indeed at any time.
If the supplied ImageReadParam
contains
optional setting values not supported by this reader (e.g.
source render size or any format-specific settings), they will
be ignored.
true
if the image format understood by
this reader supports thumbnail preview images associated with
it. The default implementation returns false
.
If this method returns false
,
hasThumbnails
and getNumThumbnails
will return false
and 0
,
respectively, and readThumbnail
will throw an
UnsupportedOperationException
, regardless of their
arguments.
A reader that does not support thumbnails need not implement any of the thumbnail-related methods.
Raster
object containing the raw pixel data
from the image stream, without any color conversion applied. The
application must determine how to interpret the pixel data by other
means. Any destination or image-type parameters in the supplied
ImageReadParam
object are ignored, but all other
parameters are used exactly as in the read
method, except that any destination offset is used as a logical rather
than a physical offset. The size of the returned Raster
will always be that of the source region clipped to the actual image.
Logical offsets in the stream itself are ignored.
This method allows formats that normally apply a color conversion, such as JPEG, and formats that do not normally have an associated colorspace, such as remote sensing or medical imaging data, to provide access to raw pixel data.
Any registered readUpdateListener
s are ignored, as
there is no BufferedImage
, but all other listeners are
called exactly as they are for the read
method.
If
returns
false
, this method throws an
UnsupportedOperationException
.
If the supplied ImageReadParam
contains
optional setting values not supported by this reader (e.g.
source render size or any format-specific settings), they will
be ignored.
The default implementation throws an
UnsupportedOperationException
.
thumbnailIndex
, associated with the image indexed
by ImageIndex
as a BufferedImage
.
Any registered IIOReadProgressListener
objects
will be notified by calling their
thumbnailStarted
, thumbnailProgress
,
and thumbnailComplete
methods.
If the reader does not support thumbnails,
(readerSupportsThumbnails
returns
false
), an UnsupportedOperationException
will be thrown regardless of whether an input source has been
set or whether the indices are in bounds.
The default implementation throws an
UnsupportedOperationException
.
tileX
and
tileY
arguments, returning it as a
BufferedImage
. If the arguments are out of range,
an IllegalArgumentException
is thrown. If the
image is not tiled, the values 0, 0 will return the entire
image; any other values will cause an
IllegalArgumentException
to be thrown.
This method is merely a convenience equivalent to calling
read(int, ImageReadParam)
with a read param
specifiying a source region having offsets of
tileX*getTileWidth(imageIndex)
,
tileY*getTileHeight(imageIndex)
and width and
height of getTileWidth(imageIndex)
,
getTileHeight(imageIndex)
; and subsampling
factors of 1 and offsets of 0. To subsample a tile, call
read
with a read param specifying this region
and different subsampling parameters.
The default implementation returns the entire image if
tileX
and tileY
are 0, or throws
an IllegalArgumentException
otherwise.
Raster
object containing the raw
pixel data from the tile, without any color conversion applied.
The application must determine how to interpret the pixel data by other
means.
If
returns
false
, this method throws an
UnsupportedOperationException
.
The default implementation checks if reading
Raster
s is supported, and if so calls
if
tileX
and tileY
are 0, or throws an
IllegalArgumentException
otherwise.
IIOReadProgressListener
objects.
The default implementation sets the
progressListeners
instance variable to
null
.
IIOReadUpdateListener
objects.
The default implementation sets the
updateListeners
instance variable to
null
.
IIOReadWarningListener
objects.
The default implementation sets the
warningListeners
and warningLocales
instance variables to null
.
IIOReadProgressListener
from the list
of registered progress listeners. If the listener was not
previously registered, or if listener
is
null
, no exception will be thrown and no action
will be taken.IIOReadUpdateListener
from the list of
registered update listeners. If the listener was not
previously registered, or if listener
is
null
, no exception will be thrown and no action
will be taken.IIOReadWarningListener
from the list of
registered error listeners. If the listener was not previously
registered, or if listener
is null
,
no exception will be thrown and no action will be taken.ImageReader
to its initial state.
The default implementation calls setInput(null,
false)
, setLocale(null)
,
removeAllIIOReadUpdateListeners()
,
removeAllIIOReadWarningListeners()
,
removeAllIIOReadProgressListeners()
, and
clearAbortRequest
.
ImageInputStream
or other Object
.
The input source must be set before any of the query or read
methods are used. If input
is null
,
any currently set input source will be removed. In any case,
the value of minIndex
will be initialized to 0.
This method is equivalent to setInput(input, false,
false)
.
ImageInputStream
or other Object
.
The input source must be set before any of the query or read
methods are used. If input
is null
,
any currently set input source will be removed. In any case,
the value of minIndex
will be initialized to 0.
The seekForwardOnly
parameter controls whether
the value returned by getMinIndex
will be
increased as each image (or thumbnail, or image metadata) is
read. If seekForwardOnly
is true, then a call to
read(index)
will throw an
IndexOutOfBoundsException
if index <
this.minIndex
; otherwise, the value of
minIndex
will be set to index
. If
seekForwardOnly
is false
, the value of
minIndex
will remain 0 regardless of any read
operations.
This method is equivalent to setInput(input,
seekForwardOnly, false)
.
ImageInputStream
or other Object
.
The input source must be set before any of the query or read
methods are used. If input
is null
,
any currently set input source will be removed. In any case,
the value of minIndex
will be initialized to 0.
The seekForwardOnly
parameter controls whether
the value returned by getMinIndex
will be
increased as each image (or thumbnail, or image metadata) is
read. If seekForwardOnly
is true, then a call to
read(index)
will throw an
IndexOutOfBoundsException
if index <
this.minIndex
; otherwise, the value of
minIndex
will be set to index
. If
seekForwardOnly
is false
, the value of
minIndex
will remain 0 regardless of any read
operations.
The ignoreMetadata
parameter, if set to
true
, allows the reader to disregard any metadata
encountered during the read. Subsequent calls to the
getStreamMetadata
and
getImageMetadata
methods may return
null
, and an IIOImage
returned from
readAll
may return null
from their
getMetadata
method. Setting this parameter may
allow the reader to work more efficiently. The reader may
choose to disregard this setting and return metadata normally.
Subclasses should take care to remove any cached information based on the previous stream, such as header information or partially decoded image data.
Use of a general Object
other than an
ImageInputStream
is intended for readers that
interact directly with a capture device or imaging protocol.
The set of legal classes is advertised by the reader's service
provider's getInputTypes
method; most readers
will return a single-element array containing only
ImageInputStream.class
to indicate that they
accept only an ImageInputStream
.
The default implementation checks the input
argument against the list returned by
originatingProvider.getInputTypes()
and fails
if the argument is not an instance of one of the classes
in the list. If the originating provider is set to
null
, the input is accepted only if it is an
ImageInputStream
.
Locale
of this
ImageReader
to the given value. A value of
null
removes any previous setting, and indicates
that the reader should localize as it sees fit.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.