Added in API level 1

FileInputStream

open class FileInputStream : InputStream
kotlin.Any
   ↳ java.io.InputStream
   ↳ java.io.FileInputStream

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.

Summary

Public constructors

Creates a FileInputStream by opening a connection to an actual file, the file named by the path name name in the file system.

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

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

Public methods
open Int

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.

open Unit

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

open FileChannel!

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

FileDescriptor!

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

open Int

Reads a byte of data from this input stream.

open Int

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

open Int
read(b: ByteArray!, off: Int, len: Int)

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

open Long
skip(n: Long)

Skips over and discards n bytes of data from the input stream.

Protected methods
open Unit

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

Inherited functions

Public constructors

FileInputStream

Added in API level 1
FileInputStream(name: String!)

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.
Exceptions
java.io.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.
java.lang.SecurityException if a security manager exists and its checkRead method denies read access to the file.

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.
Exceptions
java.io.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.
java.lang.SecurityException if a security manager exists and its checkRead method denies read access to the file.

FileInputStream

Added in API level 1
FileInputStream(fdObj: FileDescriptor!)

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.

Android-specific warning: #close() method doesn't close the fdObj provided, because this object doesn't own the file descriptor, but the caller does. The caller can call android.system.Os#close(FileDescriptor) to close the fd.

Parameters
fdObj FileDescriptor!: the file descriptor to be opened for reading.
Exceptions
java.lang.SecurityException if a security manager exists and its checkRead method denies read access to the file descriptor.

Public methods

available

Added in API level 1
open fun available(): Int

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. Returns 0 when the file position is beyond EOF. 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.

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

close

Added in API level 1
open fun close(): Unit

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.

Exceptions
java.lang.Exception if this resource cannot be closed
java.io.IOException if an I/O error occurs.

getChannel

Added in API level 1
open fun getChannel(): FileChannel!

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.

Return
FileChannel! the file channel associated with this file input stream

getFD

Added in API level 1
fun getFD(): FileDescriptor!

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

Return
FileDescriptor! the file descriptor object associated with this stream.
Exceptions
java.io.IOException if an I/O error occurs.

read

Added in API level 1
open fun read(): Int

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

Return
Int the next byte of data, or -1 if the end of the file is reached.
Exceptions
java.io.IOException if an I/O error occurs.

read

Added in API level 1
open fun read(b: ByteArray!): Int

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 ByteArray!: the buffer into which the data is read.
Return
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.
Exceptions
java.io.IOException if an I/O error occurs.
java.lang.NullPointerException if b is null.

read

Added in API level 1
open fun read(
    b: ByteArray!,
    off: Int,
    len: Int
): Int

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 ByteArray!: 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.
Return
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.
Exceptions
java.io.IOException if an I/O error occurs.
java.lang.NullPointerException If b is null.
java.lang.IndexOutOfBoundsException If off is negative, len is negative, or len is greater than b.length - off

skip

Added in API level 1
open fun skip(n: Long): Long

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, the method will try to skip backwards. In case the backing file does not support backward skip at its current position, an IOException is thrown. The actual number of bytes skipped is returned. If it skips forwards, it returns a positive value. If it skips backwards, it returns a negative value.

This method may skip more bytes than what 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.
Return
Long the actual number of bytes skipped.
Exceptions
java.io.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
protected open fun finalize(): Unit

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

Exceptions
java.lang.Throwable the Exception raised by this method
java.io.IOException if an I/O error occurs.

See Also