FileInputStream (Java Platform SE 7 ) (original) (raw)

java.lang.Object
- java.io.InputStream
- - java.io.FileInputStream
All Implemented Interfaces:
Closeable, AutoCloseable

public class FileInputStream
extends InputStream
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 usingFileReader.
Since:
JDK1.0
See Also:
File, FileDescriptor, FileOutputStream, Files.newInputStream(java.nio.file.Path, java.nio.file.OpenOption...)

Constructor Summary

Constructors

Constructor and Description
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 descriptorfdObj, which represents an existing connection to an actual file in the file system.
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.

Method Summary

Methods

Modifier and Type	Method and Description
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.
protected void	finalize() Ensures that the close method of this file input stream is called when there are no more references to it.
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.
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](../../java/io/InputStream.html "class in java.io")  
   `[mark](../../java/io/InputStream.html#mark%28int%29), [markSupported](../../java/io/InputStream.html#markSupported%28%29), [reset](../../java/io/InputStream.html#reset%28%29)`  
   * ### Methods inherited from class java.lang.[Object](../../java/lang/Object.html "class in java.lang")  
   `[clone](../../java/lang/Object.html#clone%28%29), [equals](../../java/lang/Object.html#equals%28java.lang.Object%29), [getClass](../../java/lang/Object.html#getClass%28%29), [hashCode](../../java/lang/Object.html#hashCode%28%29), [notify](../../java/lang/Object.html#notify%28%29), [notifyAll](../../java/lang/Object.html#notifyAll%28%29), [toString](../../java/lang/Object.html#toString%28%29), [wait](../../java/lang/Object.html#wait%28%29), [wait](../../java/lang/Object.html#wait%28long%29), [wait](../../java/lang/Object.html#wait%28long,%20int%29)`

Constructor Detail

 * #### FileInputStream  
 public FileInputStream([String](../../java/lang/String.html "class in java.lang") name)  
                 throws [FileNotFoundException](../../java/io/FileNotFoundException.html "class in java.io")  
 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` \- the system-dependent file name.  
 Throws:  
 `[FileNotFoundException](../../java/io/FileNotFoundException.html "class in java.io")` \- 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](../../java/lang/SecurityException.html "class in java.lang")` \- if a security manager exists and its`checkRead` method denies read access to the file.  
 See Also:  
 [SecurityManager.checkRead(java.lang.String)](../../java/lang/SecurityManager.html#checkRead%28java.lang.String%29)  
 * #### FileInputStream  
 public FileInputStream([File](../../java/io/File.html "class in java.io") file)  
                 throws [FileNotFoundException](../../java/io/FileNotFoundException.html "class in java.io")  
 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` \- the file to be opened for reading.  
 Throws:  
 `[FileNotFoundException](../../java/io/FileNotFoundException.html "class in java.io")` \- 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](../../java/lang/SecurityException.html "class in java.lang")` \- if a security manager exists and its`checkRead` method denies read access to the file.  
 See Also:  
 [File.getPath()](../../java/io/File.html#getPath%28%29), [SecurityManager.checkRead(java.lang.String)](../../java/lang/SecurityManager.html#checkRead%28java.lang.String%29)  
 * #### FileInputStream  
 public FileInputStream([FileDescriptor](../../java/io/FileDescriptor.html "class in java.io") 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](../../java/io/FileDescriptor.html#valid%28%29). However, if the methods are invoked on the resulting stream to attempt I/O on the stream, an `IOException` is thrown.  
 Parameters:  
 `fdObj` \- the file descriptor to be opened for reading.  
 Throws:  
 `[SecurityException](../../java/lang/SecurityException.html "class in java.lang")` \- if a security manager exists and its`checkRead` method denies read access to the file descriptor.  
 See Also:  
 [SecurityManager.checkRead(java.io.FileDescriptor)](../../java/lang/SecurityManager.html#checkRead%28java.io.FileDescriptor%29)

Method Detail

* #### read  
public int read()  
         throws [IOException](../../java/io/IOException.html "class in java.io")  
Reads a byte of data from this input stream. This method blocks if no input is yet available.  
**Specified by:**  
`[read](../../java/io/InputStream.html#read%28%29)` in class `[InputStream](../../java/io/InputStream.html "class in java.io")`  
Returns:  
the next byte of data, or `-1` if the end of the file is reached.  
Throws:  
`[IOException](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
* #### read  
public int read(byte[] b)  
         throws [IOException](../../java/io/IOException.html "class in java.io")  
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.  
**Overrides:**  
`[read](../../java/io/InputStream.html#read%28byte[]%29)` in class `[InputStream](../../java/io/InputStream.html "class in java.io")`  
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](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
See Also:  
[InputStream.read(byte\[\], int, int)](../../java/io/InputStream.html#read%28byte[],%20int,%20int%29)  
* #### read  
public int read(byte[] b,  
       int off,  
       int len)  
         throws [IOException](../../java/io/IOException.html "class in java.io")  
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.  
**Overrides:**  
`[read](../../java/io/InputStream.html#read%28byte[],%20int,%20int%29)` in class `[InputStream](../../java/io/InputStream.html "class in java.io")`  
Parameters:  
`b` \- the buffer into which the data is read.  
`off` \- the start offset in the destination array `b`  
`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:  
`[NullPointerException](../../java/lang/NullPointerException.html "class in java.lang")` \- If `b` is `null`.  
`[IndexOutOfBoundsException](../../java/lang/IndexOutOfBoundsException.html "class in java.lang")` \- If `off` is negative,`len` is negative, or `len` is greater than`b.length - off`  
`[IOException](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
See Also:  
[InputStream.read()](../../java/io/InputStream.html#read%28%29)  
* #### skip  
public long skip(long n)  
          throws [IOException](../../java/io/IOException.html "class in java.io")  
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](../../java/io/InputStream.html "class in java.io") 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.  
**Overrides:**  
`[skip](../../java/io/InputStream.html#skip%28long%29)` in class `[InputStream](../../java/io/InputStream.html "class in java.io")`  
Parameters:  
`n` \- the number of bytes to be skipped.  
Returns:  
the actual number of bytes skipped.  
Throws:  
`[IOException](../../java/io/IOException.html "class in java.io")` \- if n is negative, if the stream does not support seek, or if an I/O error occurs.  
* #### available  
public int available()  
              throws [IOException](../../java/io/IOException.html "class in java.io")  
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.  
**Overrides:**  
`[available](../../java/io/InputStream.html#available%28%29)` in class `[InputStream](../../java/io/InputStream.html "class in java.io")`  
Returns:  
an estimate of the number of remaining bytes that can be read (or skipped over) from this input stream without blocking.  
Throws:  
`[IOException](../../java/io/IOException.html "class in java.io")` \- if this file input stream has been closed by calling`close` or an I/O error occurs.  
* #### close  
public void close()  
           throws [IOException](../../java/io/IOException.html "class in java.io")  
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.  
**Specified by:**  
`[close](../../java/io/Closeable.html#close%28%29)` in interface `[Closeable](../../java/io/Closeable.html "interface in java.io")`  
**Specified by:**  
`[close](../../java/lang/AutoCloseable.html#close%28%29)` in interface `[AutoCloseable](../../java/lang/AutoCloseable.html "interface in java.lang")`  
**Overrides:**  
`[close](../../java/io/InputStream.html#close%28%29)` in class `[InputStream](../../java/io/InputStream.html "class in java.io")`  
Throws:  
`[IOException](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
* #### getFD  
public final [FileDescriptor](../../java/io/FileDescriptor.html "class in java.io") getFD()  
                           throws [IOException](../../java/io/IOException.html "class in java.io")  
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](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
See Also:  
[FileDescriptor](../../java/io/FileDescriptor.html "class in java.io")  
* #### getChannel  
public [FileChannel](../../java/nio/channels/FileChannel.html "class in java.nio.channels") getChannel()  
Returns the unique [FileChannel](../../java/nio/channels/FileChannel.html "class in java.nio.channels") object associated with this file input stream.  
 The initial [position](../../java/nio/channels/FileChannel.html#position%28%29) 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:  
the file channel associated with this file input stream  
Since:  
1.4  
* #### finalize  
protected void finalize()  
                 throws [IOException](../../java/io/IOException.html "class in java.io")  
Ensures that the `close` method of this file input stream is called when there are no more references to it.  
**Overrides:**  
`[finalize](../../java/lang/Object.html#finalize%28%29)` in class `[Object](../../java/lang/Object.html "class in java.lang")`  
Throws:  
`[IOException](../../java/io/IOException.html "class in java.io")` \- if an I/O error occurs.  
See Also:  
[close()](../../java/io/FileInputStream.html#close%28%29)

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FileInputStream (Java Platform SE 7 ) (original) (raw)

Constructor Summary

Method Summary

Constructor Detail

Method Detail