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Class java.io.FileInputStream

java.lang.Object
  |
  +--java.io.InputStream
        |
        +--java.io.FileInputStream

public class FileInputStream

extends java.io.InputStream

A FileInputStream obtains input bytes from a file in a file system. What files are available depends on the host environment.

Since:

JDK1.0

Version:

1.38, 06/29/98

See Also:

File, java.io.FileDescriptor, java.io.FileOutputStream

Field Summary

java.io.FileDescriptor

fd

Constructor Summary

FileInputStream(java.lang.String name)
Creates a FileInputStream by opening a connection to an actual file, the file named by the path name name in the file system.

FileInputStream(File file)
Creates a FileInputStream by opening a connection to an actual file, the file named by the File object file in the file system.

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

Method Summary

static void	()
int	available() Returns the number of bytes that can be read from this file input stream without blocking.
void	close() Closes this file input stream and releases any system resources associated with the stream.
void	finalize() Ensures that the close method of this file input stream is called when there are no more references to it.
java.io.FileDescriptor	getFD() Returns the FileDescriptor object that represents the connection to the actual file in the file system being used by this FileInputStream.
static void	initIDs()
void	open(java.lang.String name) Opens the specified file for reading.
int	readBytes(byte[] b, int off, int len) Reads a subarray as a sequence of bytes.
int	read() Reads a byte of data from this input stream.
int	read(byte[] b) Reads up to b.length bytes of data from this input stream into an array of bytes.
int	read(byte[] b, int off, int len) Reads up to len bytes of data from this input stream into an array of bytes.
long	skip(long n) Skips over and discards n bytes of data from the input stream.

Methods inherited from class java.io.InputStream

available, close, mark, markSupported, read, read, read, reset, skip

Methods inherited from class java.lang.Object

, clone, equals, finalize, getClass, hashCode, notifyAll, notify, registerNatives, toString, wait, wait, wait

Field Detail

fd

private java.io.FileDescriptor fd

Constructor Detail

FileInputStream

public FileInputStream(java.lang.String name)
                throws FileNotFoundException

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 actual file cannot be opened, a FileNotFoundException is thrown.

Parameters:

name - the system-dependent file name.

Throws:

FileNotFoundException - if the file is not found.

java.lang.SecurityException - if a security manager exists, its checkRead method is called with the name argument to see if the application is allowed read access to the file.

See Also:

checkRead(java.lang.String)

FileInputStream

public FileInputStream(File file)
                throws FileNotFoundException

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 actual file cannot be opened, a FileNotFoundException is thrown.

Parameters:

file - the file to be opened for reading.

Throws:

FileNotFoundException - if the file is not found.

java.lang.SecurityException - if a security manager exists, its checkRead method is called with the pathname of this File argument to see if the application is allowed read access to the file.

See Also:

getPath(), checkRead(java.lang.String)

FileInputStream

public FileInputStream(java.io.FileDescriptor fdObj)

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

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

Parameters:

fdObj - the file descriptor to be opened for reading.

Throws:

java.lang.SecurityException - if a security manager exists, its checkRead method is called with the file descriptor to see if the application is allowed to read from the specified file descriptor.

See Also:

checkRead(java.io.FileDescriptor)

Method Detail

open

private void open(java.lang.String name)
          throws IOException

Opens the specified file for reading.

Parameters:

name - the name of the file

read

public int read()
        throws IOException

Reads a byte of data from this input stream. This method blocks if no input is yet available.

Returns:

the next byte of data, or -1 if the end of the file is reached.

Throws:

IOException - if an I/O error occurs.

Overrides:

read in class java.io.InputStream

readBytes

private int readBytes(byte[] b,
                      int off,
                      int len)
              throws IOException

Reads a subarray as a sequence of bytes.

Parameters:

b - the data to be written

off - the start offset in the data

len - the number of bytes that are written

Throws:

IOException - If an I/O error has occurred.

read

public int read(byte[] b)
        throws IOException

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.

Parameters:

b - the buffer into which the data is read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the file has been reached.

Throws:

IOException - if an I/O error occurs.

Overrides:

read in class java.io.InputStream

read

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

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

Parameters:

b - the buffer into which the data is read.

off - the start offset of the data.

len - the maximum number of bytes read.

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the file has been reached.

Throws:

IOException - if an I/O error occurs.

Overrides:

read in class java.io.InputStream

skip

public 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. The actual number of bytes skipped is returned.

Parameters:

n - the number of bytes to be skipped.

Returns:

the actual number of bytes skipped.

Throws:

IOException - if an I/O error occurs.

Overrides:

skip in class java.io.InputStream

available

public int available()
             throws IOException

Returns the number of bytes that can be read from this file input stream without blocking.

Returns:

the number of bytes that can be read from this file input stream without blocking.

Throws:

IOException - if an I/O error occurs.

Overrides:

available in class java.io.InputStream

close

public void close()
          throws IOException

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

Throws:

IOException - if an I/O error occurs.

Overrides:

close in class java.io.InputStream

getFD

public final java.io.FileDescriptor getFD()
                                  throws IOException

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

Returns:

the file descriptor object associated with this stream.

Throws:

IOException - if an I/O error occurs.

See Also:

java.io.FileDescriptor

initIDs

private static void initIDs()

static void ()

finalize

protected void finalize()
                throws IOException

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

Throws:

IOException - if an I/O error occurs.

Overrides:

finalize in class java.lang.Object

See Also:

close()