jdk.io.InputStream
This abstract class is the superclass of all classes representing an input stream of bytes.
Applications that need to define a subclass of InputStream must always provide a method that returns the next byte of input.
This abstract class is the superclass of all classes representing an input stream of bytes. Applications that need to define a subclass of InputStream must always provide a method that returns the next byte of input.
availableclj
(available this)Returns an estimate of the number of bytes that can be read (or skipped over) from this input stream without blocking by the next invocation of a method for this input stream. The next invocation might be the same thread or another thread. A single read or skip of this many bytes will not block, but may read or skip fewer bytes.
Note that while some implementations of InputStream will return the total number of bytes in the stream, many will not. It is never correct to use the return value of this method to allocate a buffer intended to hold all data in this stream.
A subclass' implementation of this method may choose to throw an IOException if this input stream has been closed by invoking the close() method.
The available method for class InputStream always returns 0.
This method should be overridden by subclasses.
returns: an estimate of the number of bytes that can be read (or skipped
over) from this input stream without blocking or 0 when
it reaches the end of the input stream. - int
throws: java.io.IOException - if an I/O error occurs.
Returns an estimate of the number of bytes that can be read (or
skipped over) from this input stream without blocking by the next
invocation of a method for this input stream. The next invocation
might be the same thread or another thread. A single read or skip of this
many bytes will not block, but may read or skip fewer bytes.
Note that while some implementations of InputStream will return
the total number of bytes in the stream, many will not. It is
never correct to use the return value of this method to allocate
a buffer intended to hold all data in this stream.
A subclass' implementation of this method may choose to throw an
IOException if this input stream has been closed by
invoking the close() method.
The available method for class InputStream always
returns 0.
This method should be overridden by subclasses.
returns: an estimate of the number of bytes that can be read (or skipped
over) from this input stream without blocking or 0 when
it reaches the end of the input stream. - `int`
throws: java.io.IOException - if an I/O error occurs.closeclj
(close this)Closes this input stream and releases any system resources associated with the stream.
The close method of InputStream does nothing.
throws: java.io.IOException - if an I/O error occurs.
Closes this input stream and releases any system resources associated with the stream. The close method of InputStream does nothing. throws: java.io.IOException - if an I/O error occurs.
markclj
(mark this readlimit)Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes.
The readlimit arguments tells this input stream to allow that many bytes to be read before the mark position gets invalidated.
The general contract of mark is that, if the method markSupported returns true, the stream somehow remembers all the bytes read after the call to mark and stands ready to supply those same bytes again if and whenever the method reset is called. However, the stream is not required to remember any data at all if more than readlimit bytes are read from the stream before reset is called.
Marking a closed stream should not have any effect on the stream.
The mark method of InputStream does nothing.
readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid. - int
Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes. The readlimit arguments tells this input stream to allow that many bytes to be read before the mark position gets invalidated. The general contract of mark is that, if the method markSupported returns true, the stream somehow remembers all the bytes read after the call to mark and stands ready to supply those same bytes again if and whenever the method reset is called. However, the stream is not required to remember any data at all if more than readlimit bytes are read from the stream before reset is called. Marking a closed stream should not have any effect on the stream. The mark method of InputStream does nothing. readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid. - `int`
mark-supportedclj
(mark-supported this)Tests if this input stream supports the mark and reset methods. Whether or not mark and reset are supported is an invariant property of a particular input stream instance. The markSupported method of InputStream returns false.
returns: true if this stream instance supports the mark
and reset methods; false otherwise. - boolean
Tests if this input stream supports the mark and
reset methods. Whether or not mark and
reset are supported is an invariant property of a
particular input stream instance. The markSupported method
of InputStream returns false.
returns: true if this stream instance supports the mark
and reset methods; false otherwise. - `boolean`readclj
(read this)(read this b)(read this b off len)Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read as many as len bytes, but a smaller number may be read. The number of bytes actually read is returned as an integer.
This method blocks until input data is available, end of file is detected, or an exception is thrown.
If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read at least one byte. If no byte is available because the stream is at end of file, the value -1 is returned; otherwise, at least one byte is read and stored into b.
The first byte read is stored into element b[off], the next one into b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k] through b[off+len-1] unaffected.
In every case, elements b[0] through b[off] and elements b[off+len] through b[b.length-1] are unaffected.
The read(b, off, len) method for class InputStream simply calls the method read() repeatedly. If the first such call results in an IOException, that exception is returned from the call to the read(b, off, len) method. If any subsequent call to read() results in a IOException, the exception is caught and treated as if it were end of file; the bytes read up to that point are stored into b and the number of bytes read before the exception occurred is returned. The default implementation of this method blocks until the requested amount of input data len has been read, end of file is detected, or an exception is thrown. Subclasses are encouraged to provide a more efficient implementation of this method.
b - the buffer into which the data is read. - byte[]
off - the start offset in array b at which the data is written. - int
len - the maximum number of bytes to read. - int
returns: the total number of bytes read into the buffer, or
-1 if there is no more data because the end of
the stream has been reached. - int
throws: java.io.IOException - If the first byte cannot be read for any reason other than end of file, or if the input stream has been closed, or if some other I/O error occurs.
Reads up to len bytes of data from the input stream into
an array of bytes. An attempt is made to read as many as
len bytes, but a smaller number may be read.
The number of bytes actually read is returned as an integer.
This method blocks until input data is available, end of file is
detected, or an exception is thrown.
If len is zero, then no bytes are read and
0 is returned; otherwise, there is an attempt to read at
least one byte. If no byte is available because the stream is at end of
file, the value -1 is returned; otherwise, at least one
byte is read and stored into b.
The first byte read is stored into element b[off], the
next one into b[off+1], and so on. The number of bytes read
is, at most, equal to len. Let k be the number of
bytes actually read; these bytes will be stored in elements
b[off] through b[off+k-1],
leaving elements b[off+k] through
b[off+len-1] unaffected.
In every case, elements b[0] through
b[off] and elements b[off+len] through
b[b.length-1] are unaffected.
The read(b, off, len) method
for class InputStream simply calls the method
read() repeatedly. If the first such call results in an
IOException, that exception is returned from the call to
the read(b, off, len) method. If
any subsequent call to read() results in a
IOException, the exception is caught and treated as if it
were end of file; the bytes read up to that point are stored into
b and the number of bytes read before the exception
occurred is returned. The default implementation of this method blocks
until the requested amount of input data len has been read,
end of file is detected, or an exception is thrown. Subclasses are encouraged
to provide a more efficient implementation of this method.
b - the buffer into which the data is read. - `byte[]`
off - the start offset in array b at which the data is written. - `int`
len - the maximum number of bytes to read. - `int`
returns: the total number of bytes read into the buffer, or
-1 if there is no more data because the end of
the stream has been reached. - `int`
throws: java.io.IOException - If the first byte cannot be read for any reason other than end of file, or if the input stream has been closed, or if some other I/O error occurs.resetclj
(reset this)Repositions this stream to the position at the time the mark method was last called on this input stream.
The general contract of reset is:
If the method markSupported returns true, then:
If the method mark has not been called since
the stream was created, or the number of bytes read from the stream
since mark was last called is larger than the argument
to mark at that last call, then an
IOException might be thrown.
If such an IOException is not thrown, then the
stream is reset to a state such that all the bytes read since the
most recent call to mark (or since the start of the
file, if mark has not been called) will be resupplied
to subsequent callers of the read method, followed by
any bytes that otherwise would have been the next input data as of
the time of the call to reset.
If the method markSupported returns false, then:
The call to reset may throw an
IOException.
If an IOException is not thrown, then the stream
is reset to a fixed state that depends on the particular type of the
input stream and how it was created. The bytes that will be supplied
to subsequent callers of the read method depend on the
particular type of the input stream.
The method reset for class InputStream does nothing except throw an IOException.
throws: java.io.IOException - if this stream has not been marked or if the mark has been invalidated.
Repositions this stream to the position at the time the
mark method was last called on this input stream.
The general contract of reset is:
If the method markSupported returns
true, then:
If the method mark has not been called since
the stream was created, or the number of bytes read from the stream
since mark was last called is larger than the argument
to mark at that last call, then an
IOException might be thrown.
If such an IOException is not thrown, then the
stream is reset to a state such that all the bytes read since the
most recent call to mark (or since the start of the
file, if mark has not been called) will be resupplied
to subsequent callers of the read method, followed by
any bytes that otherwise would have been the next input data as of
the time of the call to reset.
If the method markSupported returns
false, then:
The call to reset may throw an
IOException.
If an IOException is not thrown, then the stream
is reset to a fixed state that depends on the particular type of the
input stream and how it was created. The bytes that will be supplied
to subsequent callers of the read method depend on the
particular type of the input stream.
The method reset for class InputStream
does nothing except throw an IOException.
throws: java.io.IOException - if this stream has not been marked or if the mark has been invalidated.skipclj
(skip this n)Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from any of a number of conditions; reaching end of file before n bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If n is negative, the skip method for class InputStream always returns 0, and no bytes are skipped. Subclasses may handle the negative value differently.
The skip method of this class creates a byte array and then repeatedly reads into it until n bytes have been read or the end of the stream has been reached. Subclasses are encouraged to provide a more efficient implementation of this method. For instance, the implementation may depend on the ability to seek.
n - the number of bytes to be skipped. - long
returns: the actual number of bytes skipped. - long
throws: java.io.IOException - if the stream does not support seek, or if some other I/O error occurs.
Skips over and discards n bytes of data from this input stream. The skip method may, for a variety of reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from any of a number of conditions; reaching end of file before n bytes have been skipped is only one possibility. The actual number of bytes skipped is returned. If n is negative, the skip method for class InputStream always returns 0, and no bytes are skipped. Subclasses may handle the negative value differently. The skip method of this class creates a byte array and then repeatedly reads into it until n bytes have been read or the end of the stream has been reached. Subclasses are encouraged to provide a more efficient implementation of this method. For instance, the implementation may depend on the ability to seek. n - the number of bytes to be skipped. - `long` returns: the actual number of bytes skipped. - `long` throws: java.io.IOException - if the stream does not support seek, or if some other I/O error occurs.
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