public FileInputStream(String name) throws FileNotFoundException 
{
        this(name != null ? new File(name) : null);
}

Creates a FileInputStream by opening a connection to an actual file, the file named by the path name name in the file system. A new FileDescriptor object is created to represent this file connection.

First, if there is a security manager, its checkRead method is called with the name argument as its argument.

If the named file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading then a FileNotFoundException is thrown.

Parameters:

name - the system-dependent file name.

Throws:

FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.

SecurityException - if a security manager exists and its checkRead method denies read access to the file.

Also see:

java.lang.SecurityManager#checkRead(java.lang.String)
exception: FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.

exception: SecurityException - if a security manager exists and its checkRead method denies read access to the file.

 public FileInputStream(File file) throws FileNotFoundException 
{
        String name = (file != null ? file.getPath() : null);
        SecurityManager security = System.getSecurityManager();
        if (security != null) {
            security.checkRead(name);
        }
        if (name == null) {
            throw new NullPointerException();
        }
        fd = new FileDescriptor();
        fd.incrementAndGetUseCount();
        open(name);
}

Creates a FileInputStream by opening a connection to an actual file, the file named by the File object file in the file system. A new FileDescriptor object is created to represent this file connection.

First, if there is a security manager, its checkRead method is called with the path represented by the file argument as its argument.

If the named file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading then a FileNotFoundException is thrown.

Parameters:

file - the file to be opened for reading.

Throws:

FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.

SecurityException - if a security manager exists and its checkRead method denies read access to the file.

Also see:

java.io.File#getPath()
java.lang.SecurityManager#checkRead(java.lang.String)
exception: FileNotFoundException - if the file does not exist, is a directory rather than a regular file, or for some other reason cannot be opened for reading.

exception: SecurityException - if a security manager exists and its checkRead method denies read access to the file.

 public FileInputStream(FileDescriptor fdObj) 
{
        SecurityManager security = System.getSecurityManager();
        if (fdObj == null) {
            throw new NullPointerException();
        }
        if (security != null) {
            security.checkRead(fdObj);
        }
        fd = fdObj;
        /*
         * FileDescriptor is being shared by streams.
         * Ensure that it's GC'ed only when all the streams/channels are done
         * using it.
         */
        fd.incrementAndGetUseCount();
}

Creates a FileInputStream by using the file descriptor fdObj, which represents an existing connection to an actual file in the file system.

If there is a security manager, its checkRead method is called with the file descriptor fdObj as its argument to see if it's ok to read the file descriptor. If read access is denied to the file descriptor a SecurityException is thrown.

If fdObj is null then a NullPointerException is thrown.

This constructor does not throw an exception if fdObj is invalid . However, if the methods are invoked on the resulting stream to attempt I/O on the stream, an IOException is thrown.

Parameters:

fdObj - the file descriptor to be opened for reading.

Throws:

SecurityException - if a security manager exists and its checkRead method denies read access to the file descriptor.

Also see:

SecurityManager#checkRead(java.io.FileDescriptor)

 public native int available() throws IOException
Returns an estimate of the number of remaining bytes that can be read (or
skipped over) from this input stream without blocking by the next
invocation of a method for this input stream. The next invocation might be
the same thread or another thread.  A single read or skip of this
many bytes will not block, but may read or skip fewer bytes.

 In some cases, a non-blocking read (or skip) may appear to be
blocked when it is merely slow, for example when reading large
files over slow networks.

 public  void close() throws IOException 
{
        synchronized (closeLock) {
            if (closed) {
                return;
            }
            closed = true;
        }
        if (channel != null) {
            /*
             * Decrement the FD use count associated with the channel
             * The use count is incremented whenever a new channel
             * is obtained from this stream.
             */
           fd.decrementAndGetUseCount();
           channel.close();
        }
        /*
         * Decrement the FD use count associated with this stream
         */
        int useCount = fd.decrementAndGetUseCount();
        /*
         * If FileDescriptor is still in use by another stream, the finalizer
         * will not close it.
         */
        if ((useCount < = 0) || !isRunningFinalize()) {
            close0();
        }
}

Closes this file input stream and releases any system resources associated with the stream.

If this stream has an associated channel then the channel is closed as well.

 protected  void finalize() throws IOException 
{
        if ((fd != null) &&  (fd != FileDescriptor.in)) {
            /*
             * Finalizer should not release the FileDescriptor if another
             * stream is still using it. If the user directly invokes
             * close() then the FileDescriptor is also released.
             */
            runningFinalize.set(Boolean.TRUE);
            try {
                close();
            } finally {
                runningFinalize.set(Boolean.FALSE);
            }
        }
}

Ensures that the close method of this file input stream is called when there are no more references to it.

 public FileChannel getChannel() 
{
        synchronized (this) {
            if (channel == null) {
                channel = FileChannelImpl.open(fd, true, false, this);
                /*
                 * Increment fd's use count. Invoking the channel's close()
                 * method will result in decrementing the use count set for
                 * the channel.
                 */
                fd.incrementAndGetUseCount();
            }
            return channel;
        }
}

Returns the unique FileChannel object associated with this file input stream.

The initial position of the returned channel will be equal to the number of bytes read from the file so far. Reading bytes from this stream will increment the channel's position. Changing the channel's position, either explicitly or by reading, will change this stream's file position.

 public final FileDescriptor getFD() throws IOException 
{
        if (fd != null) return fd;
        throw new IOException();
}

Returns the FileDescriptor object that represents the connection to the actual file in the file system being used by this FileInputStream.

 public native int read() throws IOException
Reads a byte of data from this input stream. This method blocks
if no input is yet available.

 public int read(byte[] b) throws IOException 
{
        return readBytes(b, 0, b.length);
}

Reads up to b.length bytes of data from this input stream into an array of bytes. This method blocks until some input is available.

 public int read(byte[] b,
    int off,
    int len) throws IOException 
{
        return readBytes(b, off, len);
}

Reads up to len bytes of data from this input stream into an array of bytes. If len is not zero, the method blocks until some input is available; otherwise, no bytes are read and 0 is returned.

 public native long skip(long n) throws IOException
Skips over and discards n bytes of data from the
input stream.

The skip method may, for a variety of
reasons, end up skipping over some smaller number of bytes,
possibly 0. If n is negative, an
IOException is thrown, even though the skip
method of the InputStream  superclass does nothing in this case.
The actual number of bytes skipped is returned.

This method may skip more bytes than are remaining in the backing
file. This produces no exception and the number of bytes skipped
may include some number of bytes that were beyond the EOF of the
backing file. Attempting to read from the stream after skipping past
the end will result in -1 indicating the end of the file.