java.io
Class InputStream

java.lang.Object sample code for java.lang.Object definition code for java.lang.Object 
  extended by java.io.InputStream
All Implemented Interfaces:
Closeable sample code for java.io.Closeable definition code for java.io.Closeable
Direct Known Subclasses:
AudioInputStream sample code for javax.sound.sampled.AudioInputStream definition code for javax.sound.sampled.AudioInputStream , ByteArrayInputStream sample code for java.io.ByteArrayInputStream definition code for java.io.ByteArrayInputStream , FileInputStream sample code for java.io.FileInputStream definition code for java.io.FileInputStream , FilterInputStream sample code for java.io.FilterInputStream definition code for java.io.FilterInputStream , InputStream sample code for org.omg.CORBA.portable.InputStream definition code for org.omg.CORBA.portable.InputStream , ObjectInputStream sample code for java.io.ObjectInputStream definition code for java.io.ObjectInputStream , PipedInputStream sample code for java.io.PipedInputStream definition code for java.io.PipedInputStream , SequenceInputStream sample code for java.io.SequenceInputStream definition code for java.io.SequenceInputStream , StringBufferInputStream sample code for java.io.StringBufferInputStream definition code for java.io.StringBufferInputStream

public abstract class InputStream
extends Object sample code for java.lang.Object definition code for java.lang.Object
implements Closeable sample code for java.io.Closeable definition code for java.io.Closeable

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.

Since:
JDK1.0
See Also:
BufferedInputStream sample code for java.io.BufferedInputStream definition code for java.io.BufferedInputStream , ByteArrayInputStream sample code for java.io.ByteArrayInputStream definition code for java.io.ByteArrayInputStream , DataInputStream sample code for java.io.DataInputStream definition code for java.io.DataInputStream , FilterInputStream sample code for java.io.FilterInputStream definition code for java.io.FilterInputStream , read() sample code for java.io.InputStream.read() definition code for java.io.InputStream.read() , OutputStream sample code for java.io.OutputStream definition code for java.io.OutputStream , PushbackInputStream sample code for java.io.PushbackInputStream definition code for java.io.PushbackInputStream

Constructor Summary
InputStream sample code for java.io.InputStream.InputStream() definition code for java.io.InputStream.InputStream() ()
           
 
Method Summary
 int available sample code for java.io.InputStream.available() definition code for java.io.InputStream.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.
 void close sample code for java.io.InputStream.close() definition code for java.io.InputStream.close() ()
          Closes this input stream and releases any system resources associated with the stream.
 void mark sample code for java.io.InputStream.mark(int) definition code for java.io.InputStream.mark(int) (int readlimit)
          Marks the current position in this input stream.
 boolean markSupported sample code for java.io.InputStream.markSupported() definition code for java.io.InputStream.markSupported() ()
          Tests if this input stream supports the mark and reset methods.
abstract  int read sample code for java.io.InputStream.read() definition code for java.io.InputStream.read() ()
          Reads the next byte of data from the input stream.
 int read sample code for java.io.InputStream.read(byte[]) definition code for java.io.InputStream.read(byte[]) (byte[] b)
          Reads some number of bytes from the input stream and stores them into the buffer array b.
 int read sample code for java.io.InputStream.read(byte[], int, int) definition code for java.io.InputStream.read(byte[], int, int) (byte[] b, int off, int len)
          Reads up to len bytes of data from the input stream into an array of bytes.
 void reset sample code for java.io.InputStream.reset() definition code for java.io.InputStream.reset() ()
          Repositions this stream to the position at the time the mark method was last called on this input stream.
 long skip sample code for java.io.InputStream.skip(long) definition code for java.io.InputStream.skip(long) (long n)
          Skips over and discards n bytes of data from this input stream.
 
Methods inherited from class java.lang.Object sample code for java.lang.Object definition code for java.lang.Object
clone sample code for java.lang.Object.clone() definition code for java.lang.Object.clone() , equals sample code for java.lang.Object.equals(java.lang.Object) definition code for java.lang.Object.equals(java.lang.Object) , finalize sample code for java.lang.Object.finalize() definition code for java.lang.Object.finalize() , getClass sample code for java.lang.Object.getClass() definition code for java.lang.Object.getClass() , hashCode sample code for java.lang.Object.hashCode() definition code for java.lang.Object.hashCode() , notify sample code for java.lang.Object.notify() definition code for java.lang.Object.notify() , notifyAll sample code for java.lang.Object.notifyAll() definition code for java.lang.Object.notifyAll() , toString sample code for java.lang.Object.toString() definition code for java.lang.Object.toString() , wait sample code for java.lang.Object.wait() definition code for java.lang.Object.wait() , wait sample code for java.lang.Object.wait(long) definition code for java.lang.Object.wait(long) , wait sample code for java.lang.Object.wait(long, int) definition code for java.lang.Object.wait(long, int)
 

Constructor Detail

InputStream sample code for java.io.InputStream() definition code for java.io.InputStream()

public InputStream()
Method Detail

read sample code for java.io.InputStream.read() definition code for java.io.InputStream.read()

public abstract int read()
                  throws IOException sample code for java.io.IOException definition code for java.io.IOException 
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.
Throws:
IOException sample code for java.io.IOException definition code for java.io.IOException - if an I/O error occurs.

read sample code for java.io.InputStream.read(byte[]) definition code for java.io.InputStream.read(byte[])

public int read(byte[] b)
         throws IOException sample code for java.io.IOException definition code for java.io.IOException 
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 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[0], the next one into b[1], and so on. The number of bytes read is, at most, equal to the length of b. Let k be the number of bytes actually read; these bytes will be stored in elements b[0] through b[k-1], leaving elements b[k] through b[b.length-1] 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) method for class InputStream has the same effect as:

 read(b, 0, 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 sample code for java.io.IOException definition code for java.io.IOException - if an I/O error occurs.
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if b is null.
See Also:
read(byte[], int, int) sample code for java.io.InputStream.read(byte[], int, int) definition code for java.io.InputStream.read(byte[], int, int)

read sample code for java.io.InputStream.read(byte[], int, int) definition code for java.io.InputStream.read(byte[], int, int)

public int read(byte[] b,
                int off,
                int len)
         throws IOException sample code for java.io.IOException definition code for java.io.IOException 
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 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:
b - the buffer into which the data is read.
off - 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.
Throws:
IOException sample code for java.io.IOException definition code for java.io.IOException - if an I/O error occurs.
NullPointerException sample code for java.lang.NullPointerException definition code for java.lang.NullPointerException - if b is null.
See Also:
read() sample code for java.io.InputStream.read() definition code for java.io.InputStream.read()

skip sample code for java.io.InputStream.skip(long) definition code for java.io.InputStream.skip(long)

public long skip(long n)
          throws IOException sample code for java.io.IOException definition code for java.io.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 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.
Throws:
IOException sample code for java.io.IOException definition code for java.io.IOException - if an I/O error occurs.

available sample code for java.io.InputStream.available() definition code for java.io.InputStream.available()

public int available()
              throws IOException sample code for java.io.IOException definition code for java.io.IOException 
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 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.
Throws:
IOException sample code for java.io.IOException definition code for java.io.IOException - if an I/O error occurs.

close sample code for java.io.InputStream.close() definition code for java.io.InputStream.close()

public void close()
           throws IOException sample code for java.io.IOException definition code for java.io.IOException 
Closes this input stream and releases any system resources associated with the stream.

The close method of InputStream does nothing.

Specified by:
close sample code for java.io.Closeable.close() definition code for java.io.Closeable.close() in interface Closeable sample code for java.io.Closeable definition code for java.io.Closeable
Throws:
IOException sample code for java.io.IOException definition code for java.io.IOException - if an I/O error occurs.

mark sample code for java.io.InputStream.mark(int) definition code for java.io.InputStream.mark(int)

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 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.
See Also:
reset() sample code for java.io.InputStream.reset() definition code for java.io.InputStream.reset()

reset sample code for java.io.InputStream.reset() definition code for java.io.InputStream.reset()

public void reset()
           throws IOException sample code for java.io.IOException definition code for java.io.IOException 
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 except throw an IOException.

Throws:
IOException sample code for java.io.IOException definition code for java.io.IOException - if this stream has not been marked or if the mark has been invalidated.
See Also:
mark(int) sample code for java.io.InputStream.mark(int) definition code for java.io.InputStream.mark(int) , IOException sample code for java.io.IOException definition code for java.io.IOException

markSupported sample code for java.io.InputStream.markSupported() definition code for java.io.InputStream.markSupported()

public boolean markSupported()
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.
See Also:
mark(int) sample code for java.io.InputStream.mark(int) definition code for java.io.InputStream.mark(int) , reset() sample code for java.io.InputStream.reset() definition code for java.io.InputStream.reset()