Added in API level 1

FileInputStream

open class FileInputStream : InputStream

kotlin.Any
↳	java.io.InputStream
	↳	java.io.FileInputStream

Known Direct Subclasses ParcelFileDescriptor.AutoCloseInputStream ParcelFileDescriptor.AutoCloseInputStream An InputStream you can create on a ParcelFileDescriptor, which will take care of calling android.

Known Indirect Subclasses AssetFileDescriptor.AutoCloseInputStream AssetFileDescriptor.AutoCloseInputStream An InputStream you can create on a ParcelFileDescriptor, which will take care of calling android.

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

Public methods
open 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.
open Unit	close() Closes this file input stream and releases any system resources associated with the stream.
open FileChannel!	getChannel() Returns the unique FileChannel object associated with this file input stream.
FileDescriptor!	getFD() Returns the FileDescriptor object that represents the connection to the actual file in the file system being used by this FileInputStream.
open Int	read() Reads a byte of data from this input stream.
open Int	read(b: ByteArray!) 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	finalize() Ensures that the close method of this file input stream is called when there are no more references to it.

Inherited functions

From class InputStream Unit mark(readlimit: Int) Marks the current position in this input stream. A subsequent call to the reset method repositions this stream at the last marked position so that subsequent reads re-read the same bytes. The readlimit arguments tells this input stream to allow that many bytes to be read before the mark position gets invalidated. The general contract of mark is that, if the method markSupported returns true, the stream somehow remembers all the bytes read after the call to mark and stands ready to supply those same bytes again if and whenever the method reset is called. However, the stream is not required to remember any data at all if more than readlimit bytes are read from the stream before reset is called. Marking a closed stream should not have any effect on the stream. The mark method of InputStream does nothing. Boolean markSupported() Tests if this input stream supports the mark and reset methods. Whether or not mark and reset are supported is an invariant property of a particular input stream instance. The markSupported method of InputStream returns false. InputStream! nullInputStream() Returns a new InputStream that reads no bytes. The returned stream is initially open. The stream is closed by calling the close() method. Subsequent calls to close() have no effect. While the stream is open, the available(), read(), read(byte[]), read(byte[], int, int), readAllBytes(), readNBytes(byte[], int, int), readNBytes(int), skip(long), skipNBytes(long), and transferTo() methods all behave as if end of stream has been reached. After the stream has been closed, these methods all throw IOException. The markSupported() method returns false. The mark() method does nothing, and the reset() method throws IOException. ByteArray! readAllBytes() Reads all remaining bytes from the input stream. This method blocks until all remaining bytes have been read and end of stream is detected, or an exception is thrown. This method does not close the input stream. When this stream reaches end of stream, further invocations of this method will return an empty byte array. Note that this method is intended for simple cases where it is convenient to read all bytes into a byte array. It is not intended for reading input streams with large amounts of data. The behavior for the case where the input stream is asynchronously closed, or the thread interrupted during the read, is highly input stream specific, and therefore not specified. If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes have been read. Consequently the input stream may not be at end of stream and may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs. Int readNBytes(b: ByteArray!, off: Int, len: Int) Reads the requested number of bytes from the input stream into the given byte array. This method blocks until len bytes of input data have been read, end of stream is detected, or an exception is thrown. The number of bytes actually read, possibly zero, is returned. This method does not close the input stream. In the case where end of stream is reached before len bytes have been read, then the actual number of bytes read will be returned. When this stream reaches end of stream, further invocations of this method will return zero. If len is zero, then no bytes are read and 0 is returned; otherwise, there is an attempt to read up to len bytes. The first byte read is stored into element b[off], the next one in to b[off+1], and so on. The number of bytes read is, at most, equal to len. Let k be the number of bytes actually read; these bytes will be stored in elements b[off] through b[off+k-1], leaving elements b[off+k ] through b[off+len-1] unaffected. The behavior for the case where the input stream is asynchronously closed, or the thread interrupted during the read, is highly input stream specific, and therefore not specified. If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes of b have been updated with data from the input stream. Consequently the input stream and b may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs. ByteArray! readNBytes(len: Int) Reads up to a specified number of bytes from the input stream. This method blocks until the requested number of bytes has been read, end of stream is detected, or an exception is thrown. This method does not close the input stream. The length of the returned array equals the number of bytes read from the stream. If len is zero, then no bytes are read and an empty byte array is returned. Otherwise, up to len bytes are read from the stream. Fewer than len bytes may be read if end of stream is encountered. When this stream reaches end of stream, further invocations of this method will return an empty byte array. Note that this method is intended for simple cases where it is convenient to read the specified number of bytes into a byte array. The total amount of memory allocated by this method is proportional to the number of bytes read from the stream which is bounded by len. Therefore, the method may be safely called with very large values of len provided sufficient memory is available. The behavior for the case where the input stream is asynchronously closed, or the thread interrupted during the read, is highly input stream specific, and therefore not specified. If an I/O error occurs reading from the input stream, then it may do so after some, but not all, bytes have been read. Consequently the input stream may not be at end of stream and may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs. Unit reset() Repositions this stream to the position at the time the mark method was last called on this input stream. The general contract of reset is: If the method markSupported returns true, then: If the method mark has not been called since the stream was created, or the number of bytes read from the stream since mark was last called is larger than the argument to mark at that last call, then an IOException might be thrown. If such an IOException is not thrown, then the stream is reset to a state such that all the bytes read since the most recent call to mark (or since the start of the file, if mark has not been called) will be resupplied to subsequent callers of the read method, followed by any bytes that otherwise would have been the next input data as of the time of the call to reset. If the method markSupported returns false, then: The call to reset may throw an IOException. If an IOException is not thrown, then the stream is reset to a fixed state that depends on the particular type of the input stream and how it was created. The bytes that will be supplied to subsequent callers of the read method depend on the particular type of the input stream. The method reset for class InputStream does nothing except throw an IOException. Unit skipNBytes(n: Long) Skips over and discards exactly n bytes of data from this input stream. If n is zero, then no bytes are skipped. If n is negative, then no bytes are skipped. Subclasses may handle the negative value differently. This method blocks until the requested number of bytes has been skipped, end of file is reached, or an exception is thrown. If end of stream is reached before the stream is at the desired position, then an EOFException is thrown. If an I/O error occurs, then the input stream may be in an inconsistent state. It is strongly recommended that the stream be promptly closed if an I/O error occurs. Long transferTo(out: OutputStream!) Reads all bytes from this input stream and writes the bytes to the given output stream in the order that they are read. On return, this input stream will be at end of stream. This method does not close either stream. This method may block indefinitely reading from the input stream, or writing to the output stream. The behavior for the case where the input and/or output stream is asynchronously closed, or the thread interrupted during the transfer, is highly input and output stream specific, and therefore not specified. If an I/O error occurs reading from the input stream or writing to the output stream, then it may do so after some bytes have been read or written. Consequently the input stream may not be at end of stream and one, or both, streams may be in an inconsistent state. It is strongly recommended that both streams be promptly closed if an I/O error occurs.

Public constructors

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.

See Also

• java.io.File#getPath()
• java.lang.SecurityManager#checkRead(java.lang.String)

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.

See Also

• java.lang.SecurityManager#checkRead(java.io.FileDescriptor)

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.

See Also

• java.lang.SecurityManager#checkRead(java.lang.String)

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.

See Also

• java.io.FileDescriptor

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