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§2.13 Class InputStream

public  abstract  class  java.io.InputStream
    extends  java.lang.Object  (I-§1.12)
{
        // Constructors
    public InputStream();	§2.13.1

        // Methods
    public int available();	§2.13.2
    public void close();	§2.13.3
    public void mark(int  readlimit);	§2.13.4
    public boolean markSupported();	§2.13.5
    public abstract int read();	§2.13.6
    public int read(byte  b[]);	§2.13.7
    public int read(byte  b[], int  off, int  len);	§2.13.8
    public void reset();	§2.13.9
    public long skip(long  n);	§2.13.10
}
This class is an abstract class that 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 (I-§2.13.6).


Constructors

InputStream

public InputStream()
The default constructor. This constructor is only called by subclasses.

Methods

available

public int available() throws IOException
Determines the number of bytes that can be read from this input stream without blocking. The available method of InputStream returns 0. This method should be overridden by subclasses.
Returns:
the number of bytes that can be read from this input stream without blocking.
Throws
IOException (I-§2.29)
If an I/O error occurs.

close

public void close() throws IOException
Closes this input stream and releases any system resources associated with the stream.
The close method of InputStream does nothing.
Throws
IOException (I-§2.29)
If an I/O error occurs.

mark

public void mark(int readlimit)
Marks the current position in this input stream. A subsequent call to the reset method (I-§2.13.9) 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 mark method of InputStream does nothing.
Parameters:
readlimit - the maximum limit of bytes that can be read before the mark position becomes invalid.

markSupported

public boolean markSupported()
Determines if this input stream supports the mark (I-§2.13.4) and reset (I-§2.13.9) methods. The markSupported method of InputStream returns false.

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

read

public abstract int read() throws IOException
Reads the next byte of data from this 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 either 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.
Throws
IOException (I-§2.29)
If an I/O error occurs.

read

public int read(byte b[]) throws IOException
Reads up to b.length bytes of data from this input instream into an array of bytes.
The read method of InputStream calls the the read method of three arguments (I-§2.13.8) with the arguments b, 0, and b.length.

Parameters:
b - the buffer into which the data is read
Returns:
the total number of bytes read into the buffer, or -1 is there is no more data because the end of the stream has been reached.
Throws
IOException (I-§2.29)
If an I/O error occurs.

read

public int read(byte b[], int off, int len) throws IOException
Reads up to len bytes of data from this input stream into an array of bytes. This method blocks until some input is available. If the first argument is null, up to len bytes are read and discarded.
The read method of InputStream reads a single byte at a time using the read method of zero arguments (I-§2.13.6) to fill in the array. Subclasses are encouraged to provide a more efficient implementation of this method.

Parameters:
b - the buffer into which the data is read
off - the start offset of the data
len - the maximum number of bytes read
Returns:
the total number of bytes read into the buffer, or -1 is there is no more data because the end of the stream has been reached.
Throws
IOException (I-§2.29)
If an I/O error occurs.

reset

public void reset() throws IOException
Repositions this stream to the position at the time the mark method (I-§2.13.4) was last called on this input stream


The reset method of InputStream throws an IOException (I-§2.29), since input streams, by default, do not support mark and reset.

Throws
IOException (I-§2.29)
If this stream has not been marked or if the mark has been invalidated.

skip

public long skip(long n) throws IOException
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 zero. The actual number of bytes skipped is returned.
The skip method of InputStream creates a byte array of length n and then 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.
Throws
IOException (I-§2.29)
If an I/O error occurs.

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Java API Document (HTML generated by dkramer on April 22, 1996)
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