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 | |
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FileInputStream(name: String!) Creates a |
|
FileInputStream(file: File!) Creates a |
|
FileInputStream(fdObj: FileDescriptor!) Creates a |
Public methods | |
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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 |
close() Closes this file input stream and releases any system resources associated with the stream. |
open FileChannel! |
Returns the unique |
FileDescriptor! |
getFD() Returns the |
open Int |
read() Reads a byte of data from this input stream. |
open Int |
Reads up to |
open Int |
Reads up to |
open Long |
Skips over and discards |
Protected methods | |
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open Unit |
finalize() Ensures that the |
Inherited functions | |
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Public constructors
FileInputStream
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 | |
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name |
String!: the system-dependent file name. |
Exceptions | |
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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
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 | |
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file |
File!: the file to be opened for reading. |
Exceptions | |
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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
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 | |
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fdObj |
FileDescriptor!: the file descriptor to be opened for reading. |
Exceptions | |
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java.lang.SecurityException |
if a security manager exists and its checkRead method denies read access to the file descriptor. |
Public methods
available
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 | |
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Int |
an estimate of the number of remaining bytes that can be read (or skipped over) from this input stream without blocking. |
Exceptions | |
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java.io.IOException |
if this file input stream has been closed by calling close or an I/O error occurs. |
close
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 | |
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java.lang.Exception |
if this resource cannot be closed |
java.io.IOException |
if an I/O error occurs. |
getChannel
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 | |
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FileChannel! |
the file channel associated with this file input stream |
getFD
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 | |
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FileDescriptor! |
the file descriptor object associated with this stream. |
Exceptions | |
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java.io.IOException |
if an I/O error occurs. |
See Also
read
open fun read(): Int
Reads a byte of data from this input stream. This method blocks if no input is yet available.
Return | |
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Int |
the next byte of data, or -1 if the end of the file is reached. |
Exceptions | |
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java.io.IOException |
if an I/O error occurs. |
read
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 | |
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b |
ByteArray!: the buffer into which the data is read. |
Return | |
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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 | |
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java.io.IOException |
if an I/O error occurs. |
java.lang.NullPointerException |
if b is null . |
read
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 | |
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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 | |
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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 | |
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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
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 | |
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n |
Long: the number of bytes to be skipped. |
Return | |
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Long |
the actual number of bytes skipped. |
Exceptions | |
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java.io.IOException |
if n is negative, if the stream does not support seek, or if an I/O error occurs. |
Protected methods
finalize
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 | |
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java.lang.Throwable |
the Exception raised by this method |
java.io.IOException |
if an I/O error occurs. |
See Also