Class FileInputStream

public FileInputStream(File file)
            throws FileNotFoundException

This method initializes a FileInputStream to read from the specified File object. 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:

file - The File object this stream should read from

Throws:

SecurityException - If read access to the file is not allowed

FileNotFoundException - If the file does not exist or if it is a directory.

public FileInputStream(FileDescriptor fdObj)

This method initializes a FileInputStream to read from the specified FileDescriptor object. 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 specified FileDescriptor An exception is thrown if reading is not allowed.

Parameters:

fdObj - The FileDescriptor object this stream should read from

Throws:

SecurityException - If read access to the file is not allowed

public FileInputStream(String name)
            throws FileNotFoundException

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:

SecurityException - If read access to the file is not allowed

FileNotFoundException - If the file does not exist or if it is a directory

public int available()
            throws IOException

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 returns the number of unread bytes remaining in the file if the descriptor being read from is an actual file. If this method is reading from a ''special'' file such a the standard input, this method will return the appropriate value for the stream being read.

Be aware that reads on plain files that do not reside locally might possibly block even if this method says they should not. For example, a remote server might crash, preventing an NFS mounted file from being read.

Overrides:

available in interface InputStream

Returns:

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

Throws:

IOException - If an error occurs

public void close()
            throws IOException

This method closes the stream. Any futher attempts to read from the stream will likely generate an IOException since the underlying file will be closed.

Specified by:

close in interface Closeable

Overrides:

close in interface InputStream

Throws:

IOException - If an error occurs.

protected void finalize()
            throws IOException

Called on an object by the Virtual Machine at most once, at some point after the Object is determined unreachable but before it is destroyed. You would think that this means it eventually is called on every Object, but this is not necessarily the case. If execution terminates abnormally, garbage collection does not always happen. Thus you cannot rely on this method to always work. For finer control over garbage collection, use references from the java.lang.ref package.

Virtual Machines are free to not call this method if they can determine that it does nothing important; for example, if your class extends Object and overrides finalize to do simply super.finalize().

finalize() will be called by a Thread that has no locks on any Objects, and may be called concurrently. There are no guarantees on the order in which multiple objects are finalized. This means that finalize() is usually unsuited for performing actions that must be thread-safe, and that your implementation must be use defensive programming if it is to always work.

If an Exception is thrown from finalize() during garbage collection, it will be patently ignored and the Object will still be destroyed.

It is allowed, although not typical, for user code to call finalize() directly. User invocation does not affect whether automatic invocation will occur. It is also permitted, although not recommended, for a finalize() method to "revive" an object by making it reachable from normal code again.

Unlike constructors, finalize() does not get called for an object's superclass unless the implementation specifically calls super.finalize().

The default implementation does nothing.

Overrides:

finalize in interface Object

See Also:

System.gc(), System.runFinalizersOnExit(boolean), java.lang.ref

public FileChannel getChannel()

This method creates a java.nio.channels.FileChannel. Nio does not allow one to create a file channel directly. A file channel must be created by first creating an instance of Input/Output/RandomAccessFile and invoking the getChannel() method on it.

public final FileDescriptor getFD()
            throws IOException

This method returns a FileDescriptor object representing the underlying native file handle of the file this stream is reading from

Returns:

A FileDescriptor for this stream

Throws:

IOException - If an error occurs

public int read()
            throws IOException

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.

Overrides:

read in interface InputStream

Returns:

The byte read or -1 if end of stream

Throws:

IOException - If an error occurs

public int read(byte[] buf)
            throws IOException

This method reads bytes from a stream and stores them into a caller supplied buffer. This method attempts to completely fill the buffer, but can return before doing so. 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 an overloaded read method like so: read(buf, 0, buf.length)

Overrides:

read in interface InputStream

Parameters:

buf - The buffer into which the bytes read will be stored.

Returns:

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

Throws:

IOException - If an error occurs.

public int read(byte[] buf,
                int offset,
                int len)
            throws IOException

This method read bytes from a stream and stores them into a caller supplied buffer. It starts storing the data at index offset 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.

Overrides:

read in interface InputStream

Parameters:

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

offset - 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.

public long skip(long numBytes)
            throws IOException

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.

Overrides:

skip in interface InputStream

Parameters:

numBytes - The requested number of bytes to skip

Returns:

The actual number of bytes skipped.

Throws:

IOException - If an error occurs