22.3

java.io.InputStream

THE PACKAGE JAVA.IO

22.3 The Class

java.io.InputStream

An input stream makes input bytes available from some source.

public abstract class InputStream {

public abstract int read() throws IOException;

public int read(byte[] b)

throws IOException, NullPointerException;

public int read(byte[] b, int off, int len)

throws IOException, NullPointerException,

IndexOutOfBoundsException;

public long skip(long n) throws IOException;

public int available() throws IOException;

public void close() throws IOException;

public void mark(int readlimit);

public void reset() throws IOException;

public boolean markSupported();

}

22.3.1

public abstract int read() throws IOException

The general contract of

read

 is that it reads one byte from the input stream. The

byte is returned as an integer in the range

0

 to

255

  (

0x00

0xff

). If no byte is

available because the stream is at end of file, the value

 1

 is returned.

This method blocks until input data is available, end of file is detected, or an

exception is thrown.

If the byte cannot be read for any reason other than end of file, an

IOExcep 

tion

 is thrown. In particular, an

IOException

 is thrown if the input stream has

been closed ( 22.3.6).

22.3.2

public int read(byte[] b)

throws IOException, NullPointerException

The general contract of

read(b)

 is that it reads some number of bytes from the

input stream and stores them into the buffer array

b

. 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 the length of

b

 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

680