Skip to content

Most visited

Recently visited

navigation
Added in API level 1

FileInputStream

public class FileInputStream
extends InputStream

java.lang.Object
   ↳ java.io.InputStream
     ↳ java.io.FileInputStream
Known Direct Subclasses
Known Indirect Subclasses


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

FileInputStream is meant for reading streams of raw bytes such as image data. For reading streams of characters, consider using FileReader.

See also:

Summary

Public constructors

FileInputStream(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(FileDescriptor fdObj)

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

Public methods

int available()

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.

void close()

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

FileChannel getChannel()

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

final FileDescriptor getFD()

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

int read()

Reads a byte of data from this input stream.

int read(byte[] b, int off, int len)

Reads up to len bytes of data from this input stream into an array of bytes.

int read(byte[] b)

Reads up to b.length 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.

Protected methods

void finalize()

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

Inherited methods

From class java.io.InputStream
From class java.lang.Object
From interface java.io.Closeable
From interface java.lang.AutoCloseable

Public constructors

FileInputStream

Added in API level 1
FileInputStream (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. 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 String: 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.

See also:

FileInputStream

Added in API level 1
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. 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 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.

See also:

FileInputStream

Added in API level 1
FileInputStream (FileDescriptor fdObj)

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 FileDescriptor: the file descriptor to be opened for reading.

Public methods

available

Added in API level 1
int available ()

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.

Returns
int an estimate of the number of remaining bytes that can be read (or skipped over) from this input stream without blocking.
Throws
IOException if this file input stream has been closed by calling close or an I/O error occurs.

close

Added in API level 1
void close ()

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.

Throws
IOException if an I/O error occurs.

getChannel

Added in API level 1
FileChannel getChannel ()

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.

Returns
FileChannel the file channel associated with this file input stream

getFD

Added in API level 1
FileDescriptor getFD ()

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

Returns
FileDescriptor the file descriptor object associated with this stream.
Throws
IOException if an I/O error occurs.

See also:

read

Added in API level 1
int read ()

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

Returns
int the next byte of data, or -1 if the end of the file is reached.
Throws
IOException if an I/O error occurs.

read

Added in API level 1
int read (byte[] b, 
                int off, 
                int 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.

Parameters
b byte: the buffer into which the data is read.
off int: the start offset in the destination array b
len int: the maximum number of bytes read.
Returns
int 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
NullPointerException If b is null.
IndexOutOfBoundsException If off is negative, len is negative, or len is greater than b.length - off
IOException if an I/O error occurs.

read

Added in API level 1
int read (byte[] b)

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 byte: the buffer into which the data is read.
Returns
int 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.

skip

Added in API level 1
long skip (long n)

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.

Parameters
n long: the number of bytes to be skipped.
Returns
long the actual number of bytes skipped.
Throws
IOException if n is negative, if the stream does not support seek, or if an I/O error occurs.

Protected methods

finalize

Added in API level 1
void finalize ()

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.

See also:

This site uses cookies to store your preferences for site-specific language and display options.

Hooray!

This class requires API level or higher

This doc is hidden because your selected API level for the documentation is . You can change the documentation API level with the selector above the left navigation.

For more information about specifying the API level your app requires, read Supporting Different Platform Versions.