java.io

Class FileInputStream

java.lang.Object

java.io.InputStream

java.io.FileInputStream

All Implemented Interfaces:

Closeable

public class FileInputStream
extends InputStream

Reads a stream of bytes from a file. This stream uses an internal Buffer of 256 bytes.

Author:

Brian Bagnall, Sven Köhler

Constructor Summary

Constructors

Constructor and Description
FileInputStream(File f)
FileInputStream(String name) This method initializes a FileInputStream to read from the specified named file.

Method Summary

Modifier and Type	Method and Description
int	available() This method returns the number of bytes that can be read from this stream before a read can block.
int	read() This method reads an unsigned byte from the input stream and returns it as an int in the range of 0-255.
int	read(byte[] b, int off, int len) This method read bytes from a stream and stores them into a caller supplied buffer.
long	skip(long n) This method skips the specified number of bytes in the stream.

Methods inherited from class java.io.InputStream

close, mark, markSupported, read, reset

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

FileInputStream

public FileInputStream(File f)
                throws FileNotFoundException

Throws:

FileNotFoundException

FileInputStream

public FileInputStream(String name)
                throws IOException

This method initializes a FileInputStream to read from the specified named file. A security check is first made to determine whether or not access to this file is allowed. This is done by calling the checkRead() method of the SecurityManager (if one exists) with the name of this file. An exception is thrown if reading is not allowed. If the file does not exist, an exception is also thrown.

Parameters:

name - The name of the file this stream should read from

Throws:

IOException

Method Detail

available

public int available()
              throws IOException

Description copied from class: InputStream

This method returns the number of bytes that can be read from this stream before a read can block. A return of 0 indicates that blocking might (or might not) occur on the very next read attempt.

This method always returns 0 in this class

Overrides:

available in class InputStream

Returns:

The number of bytes that can be read before blocking could occur

Throws:

IOException - If an error occurs

read

public int read()
         throws IOException

Description copied from class: InputStream

This method reads an unsigned byte from the input stream and returns it as an int in the range of 0-255. This method also will return -1 if the end of the stream has been reached.

This method will block until the byte can be read.

Specified by:

read in class InputStream

Returns:

The byte read or -1 if end of stream

Throws:

IOException - If an error occurs

read

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

Description copied from class: InputStream

This method read bytes from a stream and stores them into a caller supplied buffer. It starts storing the data at index off into the buffer and attempts to read len bytes. This method can return before reading the number of bytes requested. The actual number of bytes read is returned as an int. A -1 is returned to indicate the end of the stream.

This method will block until some data can be read.

This method operates by calling the single byte read() method in a loop until the desired number of bytes are read. The read loop stops short if the end of the stream is encountered or if an IOException is encountered on any read operation except the first. If the first attempt to read a bytes fails, the IOException is allowed to propagate upward. And subsequent IOException is caught and treated identically to an end of stream condition. Subclasses can (and should if possible) override this method to provide a more efficient implementation.

Overrides:

read in class InputStream

Parameters:

b - The array into which the bytes read should be stored

off - The offset into the array to start storing bytes

len - The requested number of bytes to read

Returns:

The actual number of bytes read, or -1 if end of stream.

Throws:

IOException - If an error occurs.

skip

public long skip(long n)
          throws IOException

Description copied from class: InputStream

This method skips the specified number of bytes in the stream. It returns the actual number of bytes skipped, which may be less than the requested amount.

This method reads and discards bytes into a byte array until the specified number of bytes were skipped or until either the end of stream is reached or a read attempt returns a short count. Subclasses can override this metho to provide a more efficient implementation where one exists.

Overrides:

skip in class InputStream

Parameters:

n - The requested number of bytes to skip

Returns:

The actual number of bytes skipped.

Throws:

IOException - If an error occurs