ImageInputStream
interface.
This class is designed to reduce the number of methods that must
be implemented by subclasses.
In particular, this class handles most or all of the details of byte order interpretation, buffering, mark/reset, discarding, closing, and disposing.
ImageInputStreamImpl
.IOException
s or incorrect
behavior. Calling this method may allow classes implementing
this interface to release resources associated with the stream
such as memory, disk space, or file descriptors.
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.
flushBefore(getStreamPosition())
.IndexOutOfBoundsException
.
Calling flushBefore
may allow classes
implementing this interface to free up resources such as memory
or disk space that are being used to store data from the
stream.
readBits
method. A value of 0 indicates the
most-significant bit, and a value of 7 indicates the least
significant bit, of the byte being read.
The bit offset is set to 0 when a stream is first
opened, and is reset to 0 by calls to seek
,
skipBytes
, or any read
or
readFully
method.
java.nio.ByteOrder
enumeration.flushBefore
.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 this ImageInputStream
caches data itself in order to allow seeking backwards.
Applications may consult this in order to decide how frequently,
or whether, to flush in order to conserve cache resources.true
if this ImageInputStream
caches data itself in order to allow seeking backwards, and
the cache is kept in a temporary file. Applications may consult
this in order to decide how frequently, or whether, to flush
in order to conserve cache resources.true
if this ImageInputStream
caches data itself in order to allow seeking backwards, and
the cache is kept in main memory. Applications may consult
this in order to decide how frequently, or whether, to flush
in order to conserve cache resources.-1
is returned.reset
. Unlike a standard
InputStream
, all ImageInputStream
s
support marking. Additionally, calls to mark
and
reset
may be nested arbitrarily.
Unlike the mark
methods declared by the
Reader
InputStream
interfaces, no
readLimit
parameter is used. An arbitrary amount
of data may be read following the call to mark
.
The bit position used by the readBits
method
is saved and restored by each pair of calls to
mark
and reset
.
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.
The bit offset within the stream is reset to zero before the read occurs.
b.length
bytes from the stream, and
stores them into b
starting at index 0. The
number of bytes read is returned. If no bytes can be read
because the end of the stream has been reached, -1 is returned.
The bit offset within the stream is reset to zero before the read occurs.
len
bytes from the stream, and stores
them into b
starting at index off
.
The number of bytes read is returned. If no bytes can be read
because the end of the stream has been reached, -1
is returned.
The bit offset within the stream is reset to zero before the read occurs.
int
with the value 0
or
1
. The bit offset is advanced by one and reduced
modulo 8.long
, with the first bit read becoming the most
significant bit of the output. The read starts within the byte
indicated by getStreamPosition
, at the bit given
by getBitOffset
. The bit offset is advanced by
numBits
and reduced modulo 8.
The byte order of the stream has no effect on this method. The return value of this method is constructed as though the bits were read one at a time, and shifted into the right side of the return value, as shown by the following pseudo-code:
long accum = 0L; for (int i = 0; i < numBits; i++) { accum <<= 1; // Shift left one bit to make room accum |= readBit(); }Note that the result of
readBits(32)
may thus not
be equal to that of readInt()
if a reverse network
byte order is being used (i.e., getByteOrder() ==
false
).
If the end of the stream is encountered before all the bits
have been read, an EOFException
is thrown.
boolean
value of true
if it is nonzero, false
if it is zero.
The bit offset within the stream is reset to zero before the read occurs.
byte
value. Byte values between 0x00
and 0x7f
represent integer values between
0
and 127
. Values between
0x80
and 0xff
represent negative
values from -128
to /1
.
The bit offset within the stream is reset to zero before the read occurs.
len
bytes from the stream, and
modifies the supplied IIOByteBuffer
to indicate
the byte array, offset, and length where the data may be found.
The caller should not attempt to modify the data found in the
IIOByteBuffer
.
The bit offset within the stream is reset to zero before the read occurs.
readUnsignedShort
, except that the
result is returned using the char
datatype.
The bit offset within the stream is reset to zero before the read occurs.
double
.
The bit offset within the stream is reset to zero before the read occurs.
float
.
The bit offset within the stream is reset to zero before the read occurs.
b.length
bytes from the stream, and stores them
into b
starting at index 0
.
If the end of the stream is reached, an EOFException
will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
len
bytes from the stream, and stores them
into b
starting at index off
.
If the end of the stream is reached, an EOFException
will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
len
chars (unsigned 16-bit integers) from the
stream according to the current byte order, and
stores them into c
starting at index
off
. If the end of the stream is reached, an
EOFException
will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
len
doubles (64-bit IEEE double-precision
floats) from the stream according to the current byte order,
and stores them into d
starting at
index off
. If the end of the stream is reached,
an EOFException
will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
len
floats (32-bit IEEE single-precision
floats) from the stream according to the current byte order,
and stores them into f
starting at
index off
. If the end of the stream is reached,
an EOFException
will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
len
ints (signed 32-bit integers) from the
stream according to the current byte order, and
stores them into i
starting at index
off
. If the end of the stream is reached, an
EOFException
will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
len
longs (signed 64-bit integers) from the
stream according to the current byte order, and
stores them into l
starting at index
off
. If the end of the stream is reached, an
EOFException
will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
len
shorts (signed 16-bit integers) from the
stream according to the current byte order, and
stores them into s
starting at index
off
. If the end of the stream is reached, an
EOFException
will be thrown.
The bit offset within the stream is reset to zero before the read occurs.
int
.
The bit offset within the stream is ignored and treated as though it were zero.
String
. Note that because this method processes
bytes, it does not support input of the full Unicode character
set.
If end of file is encountered before even one byte can be
read, then null
is returned. Otherwise, each byte
that is read is converted to type char
by
zero-extension. If the character '\n'
is
encountered, it is discarded and reading ceases. If the
character '\r'
is encountered, it is discarded
and, if the following byte converts to the character
'\n'
, then that is discarded also; reading then
ceases. If end of file is encountered before either of the
characters '\n'
and '\r'
is
encountered, reading ceases. Once reading has ceased, a
String
is returned that contains all the
characters read and not discarded, taken in order. Note that
every character in this string will have a value less than
\u0100
, that is, (char)256
.
The bit offset within the stream is reset to zero before the read occurs.
long
.
The bit offset within the stream is reset to zero before the read occurs.
short
value.
The bit offset within the stream is reset to zero before the read occurs.
0xff
in order to strip off
any sign-extension bits, and returns it as a byte
value.
Thus, byte values between 0x00
and
0x7f
are simply returned as integer values between
0
and 127
. Values between
0x80
and 0xff
, which normally
represent negative byte
values, will be mapped into
positive integers between 128
and
255
.
The bit offset within the stream is reset to zero before the read occurs.
0xffffffffL
in order to
strip off any sign-extension bits, and returns the result as an
unsigned long
value.
The bit offset within the stream is reset to zero before the read occurs.
int
, masks it with
0xffff
in order to strip off any sign-extension
buts, and returns the result as an unsigned int
value.
The bit offset within the stream is reset to zero before the read occurs.
readUTF
is that
it reads a representation of a Unicode character string encoded
in modified UTF-8 format; this string of characters is
then returned as a String
.
First, two bytes are read and used to construct an unsigned
16-bit integer in the manner of the
readUnsignedShort
method, using network byte order
(regardless of the current byte order setting). This integer
value is called the UTF length and specifies the number
of additional bytes to be read. These bytes are then converted
to characters by considering them in groups. The length of each
group is computed from the value of the first byte of the
group. The byte following a group, if any, is the first byte of
the next group.
If the first byte of a group matches the bit pattern
0xxxxxxx
(where x
means "may be
0
or 1
"), then the group consists of
just that byte. The byte is zero-extended to form a character.
If the first byte of a group matches the bit pattern
110xxxxx
, then the group consists of that byte
a
and a second byte b
. If there is no
byte b
(because byte a
was the last
of the bytes to be read), or if byte b
does not
match the bit pattern 10xxxxxx
, then a
UTFDataFormatException
is thrown. Otherwise, the
group is converted to the character:
(char)(((a& 0x1F) << 6) | (b & 0x3F))
If the first byte of a group matches the bit pattern
1110xxxx
, then the group consists of that byte
a
and two more bytes b
and
c
. If there is no byte c
(because
byte a
was one of the last two of the bytes to be
read), or either byte b
or byte c
does not match the bit pattern 10xxxxxx
, then a
UTFDataFormatException
is thrown. Otherwise, the
group is converted to the character:
(char)(((a & 0x0F) << 12) | ((b & 0x3F) << 6) | (c & 0x3F))
If the first byte of a group matches the pattern
1111xxxx
or the pattern 10xxxxxx
,
then a UTFDataFormatException
is thrown.
If end of file is encountered at any time during this
entire process, then an EOFException
is thrown.
After every group has been converted to a character by this
process, the characters are gathered, in the same order in
which their corresponding groups were read from the input
stream, to form a String
, which is returned.
The current byte order setting is ignored.
The bit offset within the stream is reset to zero before the read occurs.
Note: This method should not be used in the implementation of image formats that use standard UTF-8, because the modified UTF-8 used here is incompatible with standard UTF-8.
mark
.
Calls to reset
without a corresponding call
to mark
have no effect.
An IOException
will be thrown if the previous
marked position lies in the discarded portion of the stream.
An IndexOutOfBoundsException
will be thrown if
pos
is smaller than the flushed position (as
returned by getflushedPosition
).
It is legal to seek past the end of the file; an
EOFException
will be thrown only if a read is
performed.
getStreamPosition
, is left unchanged.
A value of 0 indicates the
most-significant bit, and a value of 7 indicates the least
significant bit, of the byte being read. The enumeration class java.nio.ByteOrder
is
used to specify the byte order. A value of
ByteOrder.BIG_ENDIAN
specifies so-called
big-endian or network byte order, in which the high-order byte
comes first. Motorola and Sparc processors store data in this
format, while Intel processors store data in the reverse
ByteOrder.LITTLE_ENDIAN
order.
The byte order has no effect on the results returned from
the readBits
method (or the value written by
ImageOutputStream.writeBits
).
skipBytes(int)
except
that it allows for a larger skip distance.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.