Package java.io

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Class InputStream

public  abstract  class  java.io.InputStream
    extends  java.lang.Object  
{
        // Constructors
    public InputStream();	

        // Methods
    public int available();	
    public void close();	
    public void mark(int  readlimit);	
    public boolean markSupported();	
    public abstract int read();	
    public int read(byte  b[]);	
    public int read(byte  b[], int  off, int  len);	
    public void reset();	
    public long skip(long  n);	
}

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 .

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.

Return Value:

Returns the number of bytes that can be read from this input stream without blocking.

Throw:

IOException

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.

Throw:

IOException

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 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.

Parameter	Description
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 and reset methods. The markSupported method of InputStream returns false.

Return Value:

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.

Return Value:

Returns the next byte of data, or -1 if the end of the stream is reached.

Throw:

IOException

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 with the arguments b, 0, and b.length.

Return Value:

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.

Parameter	Description
b	the buffer into which the data is read

Throw:

IOException

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 to fill in the array. Subclasses are encouraged to provide a more efficient implementation of this method.

Return Value:

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.

Parameter	Description
b	the buffer into which the data is read
off	the start offset of the data
len	the maximum number of bytes read

Throw:

IOException

If an I/O error occurs.

reset

public void reset() 

throws IOException 

Repositions this stream to the position at the time the mark method was last called on this input stream

The reset method of InputStream throws an IOException , since input streams, by default, do not support mark and reset.

Throw:

IOException

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.

Return Value:

Returns the actual number of bytes skipped.

Parameter	Description
n	the number of bytes to be skipped

Throw:

IOException

If an I/O error occurs.