java::io::InputStream Class Reference

Inheritance diagram for java::io::InputStream:

Inheritance graph
java::io::BufferedInputStreamjava::io::ByteArrayInputStreamjava::io::FileInputStreamjava::io::FilterInputStreamjava::io::RandomAccessFilejava::lang::Interfacejava::lang::Objectjava::io::DataInputStream
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Collaboration diagram for java::io::InputStream:

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java::lang::Interfacejava::lang::Object
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List of all members.


Detailed Description

The interface 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.

Author:
Arthur van Hoff
Version:
1.36, 02/02/00
Since:
JDK1.0

Public Member Functions

virtual jint read ()=0
 Reads the next byte of data from the input stream.
virtual jint read (Array< jbyte > &b, jint ofs=0, jint len=-1)=0
 Reads up to len bytes of data from the input stream into an array of bytes.
virtual jlong skip (jlong n)=0
 Skips over and discards n bytes of data from this input stream.
virtual jint available ()
 Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream.
virtual void close ()
 Closes this input stream and releases any system resources associated with the stream.
virtual void mark (jint readlimit=0)
 Marks the current position in this input stream.
virtual void reset ()
 Repositions this stream to the position at the time the mark method was last called on this input stream.
virtual jboolean markSupported ()
 Tests if this input stream supports the mark and reset methods.

Member Function Documentation

virtual jint java::io::InputStream::read (  )  [pure virtual]

Reads the next byte of data from the input stream.

The value byte is returned as an int in the range 0 to 255. If no byte is available because the end of the stream has been reached, the value -1 is returned. This method blocks until input data is available, the end of the stream is detected, or an exception is thrown.

A subclass must provide an implementation of this method.

Returns:
the next byte of data, or -1 if the end of the stream is reached.
Exceptions:
IOException if an I/O error occurs.

Implemented in java::io::BufferedInputStream, java::io::ByteArrayInputStream, java::io::DataInputStream, java::io::FileInputStream, java::io::FilterInputStream, and java::io::RandomAccessFile.

virtual jint java::io::InputStream::read ( Array< jbyte > &  b,
jint  ofs = 0,
jint  len = -1 
) [pure virtual]

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, possibly zero. 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 b is null, a NullPointerException is thrown.

If off is negative, or len is negative, or off+len is greater than the length of the array b, then an IndexOutOfBoundsException 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.

If the first byte cannot be read for any reason other than end of file, then an IOException is thrown. In particular, an IOException is thrown if the input stream has been closed.

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. Subclasses are encouraged to provide a more efficient implementation of this method.

Parameters:
src the buffer into which the data is read.
ofs the start offset in array b at which the data is written.
len the maximum number of bytes to read.
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.
Exceptions:
IOException if an I/O error occurs.

Implemented in java::io::BufferedInputStream, java::io::ByteArrayInputStream, java::io::DataInputStream, java::io::FileInputStream, java::io::FilterInputStream, and java::io::RandomAccessFile.

virtual jlong java::io::InputStream::skip ( jlong  n  )  [pure virtual]

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, no bytes are skipped.

The skip method of InputStream 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.

Parameters:
n the number of bytes to be skipped.
Returns:
the actual number of bytes skipped.
Exceptions:
IOException if an I/O error occurs.

Implemented in java::io::BufferedInputStream, java::io::ByteArrayInputStream, java::io::DataInputStream, java::io::FileInputStream, java::io::FilterInputStream, and java::io::RandomAccessFile.

virtual jint java::io::InputStream::available (  )  [virtual]

Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next caller of a method for this input stream.

The next caller might be the same thread or or another thread.

The available method for class InputStream always returns 0.

This method should be overridden by subclasses.

Returns:
the number of bytes that can be read from this input stream without blocking.
Exceptions:
IOException if an I/O error occurs.

Reimplemented in java::io::BufferedInputStream, java::io::ByteArrayInputStream, java::io::FileInputStream, java::io::FilterInputStream, and java::io::RandomAccessFile.

virtual void java::io::InputStream::close (  )  [virtual]

Closes this input stream and releases any system resources associated with the stream.

The close method of InputStream does nothing.

Exceptions:
IOException if an I/O error occurs.

Reimplemented in java::io::BufferedInputStream, java::io::ByteArrayInputStream, java::io::FileInputStream, java::io::FilterInputStream, and java::io::RandomAccessFile.

virtual void java::io::InputStream::mark ( jint  readlimit = 0  )  [virtual]

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.

The mark method of InputStream does nothing.

Parameters:
readlimit the maximum limit of bytes that can be read before the mark position becomes invalid.

Reimplemented in java::io::BufferedInputStream, java::io::ByteArrayInputStream, and java::io::FilterInputStream.

virtual void java::io::InputStream::reset (  )  [virtual]

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:

The method reset for class InputStream does nothing and always throws an IOException.

Exceptions:
IOException if this stream has not been marked or if the mark has been invalidated.

Reimplemented in java::io::BufferedInputStream, java::io::ByteArrayInputStream, and java::io::FilterInputStream.

virtual jboolean java::io::InputStream::markSupported (  )  [virtual]

Tests if this input stream supports the mark and reset methods.

The markSupported method of InputStream returns false.

Returns:
true if this true type supports the mark and reset method; false otherwise.

Reimplemented in java::io::BufferedInputStream, java::io::ByteArrayInputStream, and java::io::FilterInputStream.


The documentation for this class was generated from the following file:
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