Class FileOutputStream
- All Implemented Interfaces:
Closeable,Flushable,AutoCloseable
File or to a FileDescriptor. Whether or not
a file is available or may be created depends upon the underlying
platform. Some platforms, in particular, allow a file to be opened
for writing by only one FileOutputStream (or other
file-writing object) at a time. In such situations the constructors in
this class will fail if the file involved is already open.
FileOutputStream is meant for writing streams of raw bytes
such as image data. For writing streams of characters, consider using
FileWriter.
- API Note:
- The
close()method should be called to release resources used by this stream, either directly, or with thetry-with-resources statement. - Implementation Requirements:
- Subclasses are responsible for the cleanup of resources acquired by the subclass.
Subclasses requiring that resource cleanup take place after a stream becomes
unreachable should use
Cleaneror some other mechanism. - Since:
- 1.0
- See Also:
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Constructor Summary
ConstructorsConstructorDescriptionFileOutputStream(File file) Creates a file output stream to write to the file represented by the specifiedFileobject.FileOutputStream(FileDescriptor fdObj) Creates a file output stream to write to the specified file descriptor, which represents an existing connection to an actual file in the file system.FileOutputStream(File file, boolean append) Creates a file output stream to write to the file represented by the specifiedFileobject.FileOutputStream(String name) Creates a file output stream to write to the file with the specified name.FileOutputStream(String name, boolean append) Creates a file output stream to write to the file with the specified name. -
Method Summary
Modifier and TypeMethodDescriptionvoidclose()Closes this file output stream and releases any system resources associated with this stream.Returns the uniqueFileChannelobject associated with this file output stream.final FileDescriptorgetFD()Returns the file descriptor associated with this stream.voidwrite(byte[] b) Writesb.lengthbytes from the specified byte array to this file output stream.voidwrite(byte[] b, int off, int len) Writeslenbytes from the specified byte array starting at offsetoffto this file output stream.voidwrite(int b) Writes the specified byte to this file output stream.Methods declared in class java.io.OutputStream
flush, nullOutputStream
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Constructor Details
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FileOutputStream
Creates a file output stream to write to the file with the specified name. If the file exists, it is truncated, otherwise a new file is created. Symbolic links are automatically redirected to the target of the link. A newFileDescriptorobject is created to represent this file connection.If the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason then a
FileNotFoundExceptionis thrown.- Implementation Requirements:
- Invoking this constructor with the parameter
nameis equivalent to invokingnew FileOutputStream(name, false). - Parameters:
name- the system-dependent filename- Throws:
FileNotFoundException- if the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason
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FileOutputStream
Creates a file output stream to write to the file with the specified name. If the file exists, it is truncated unless the second argument istrue, in which case bytes will be written to the end of the file rather than the beginning. If the file does not exist, it is created. Symbolic links are automatically redirected to the target of the link. A newFileDescriptorobject is created to represent this file connection.If the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason then a
FileNotFoundExceptionis thrown.- Parameters:
name- the system-dependent file nameappend- iftrue, then bytes will be written to the end of the file rather than the beginning- Throws:
FileNotFoundException- if the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason.- Since:
- 1.1
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FileOutputStream
Creates a file output stream to write to the file represented by the specifiedFileobject. If the file exists, it is truncated, otherwise a new file is created. Symbolic links are automatically redirected to the target of the link. A newFileDescriptorobject is created to represent this file connection.If the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason then a
FileNotFoundExceptionis thrown.- Parameters:
file- the file to be opened for writing.- Throws:
FileNotFoundException- if the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason- See Also:
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FileOutputStream
Creates a file output stream to write to the file represented by the specifiedFileobject. If the file exists, it is truncated unless the second argument istrue, in which case bytes will be written to the end of the file rather than the beginning. If the file does not exist, it is created. Symbolic links are automatically redirected to the target of the link. A newFileDescriptorobject is created to represent this file connection.If the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason then a
FileNotFoundExceptionis thrown.- Parameters:
file- the file to be opened for writing.append- iftrue, then bytes will be written to the end of the file rather than the beginning- Throws:
FileNotFoundException- if the file exists but is a directory rather than a regular file, does not exist but cannot be created, or cannot be opened for any other reason- Since:
- 1.4
- See Also:
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FileOutputStream
Creates a file output stream to write to the specified file descriptor, which represents an existing connection to an actual file in the file system.If
fdObjis null then aNullPointerExceptionis thrown.This constructor does not throw an exception if
fdObjisinvalid. However, if the methods are invoked on the resulting stream to attempt I/O on the stream, anIOExceptionis thrown.- Parameters:
fdObj- the file descriptor to be opened for writing
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Method Details
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write
Writes the specified byte to this file output stream. Implements thewritemethod ofOutputStream.- Specified by:
writein classOutputStream- Parameters:
b- the byte to be written.- Throws:
IOException- if an I/O error occurs.
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write
Writesb.lengthbytes from the specified byte array to this file output stream.- Overrides:
writein classOutputStream- Parameters:
b- the data.- Throws:
IOException- if an I/O error occurs.- See Also:
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write
Writeslenbytes from the specified byte array starting at offsetoffto this file output stream.- Overrides:
writein classOutputStream- Parameters:
b- the data.off- the start offset in the data.len- the number of bytes to write.- Throws:
IOException- if an I/O error occurs.IndexOutOfBoundsException- Ifoffis negative,lenis negative, orlenis greater thanb.length - off
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close
Closes this file output stream and releases any system resources associated with this stream. This file output stream may no longer be used for writing bytes.If this stream has an associated channel then the channel is closed as well.
- Specified by:
closein interfaceAutoCloseable- Specified by:
closein interfaceCloseable- Overrides:
closein classOutputStream- API Note:
- Overriding
close()to perform cleanup actions is reliable only when called directly or when called by try-with-resources. - Implementation Requirements:
- Subclasses requiring that resource cleanup take place after a stream becomes
unreachable should use the
Cleanermechanism.If this stream has an associated channel then this method will close the channel, which in turn will close this stream. Subclasses that override this method should be prepared to handle possible reentrant invocation.
- Throws:
IOException- if an I/O error occurs.
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getFD
Returns the file descriptor associated with this stream.- Returns:
- the
FileDescriptorobject that represents the connection to the file in the file system being used by thisFileOutputStreamobject. - Throws:
IOException- if an I/O error occurs.- See Also:
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getChannel
Returns the uniqueFileChannelobject associated with this file output stream.The initial
positionof the returned channel will be equal to the number of bytes written to the file so far unless this stream is in append mode, in which case it will be equal to the size of the file. Writing bytes to this stream will increment the channel's position accordingly. Changing the channel's position, either explicitly or by writing, will change this stream's file position.- Returns:
- the file channel associated with this file output stream
- Since:
- 1.4
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