- java.lang.Object
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- java.io.OutputStream
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- java.io.FileOutputStream
 
 
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- All Implemented Interfaces:
- Closeable,- Flushable,- AutoCloseable
 
 public class FileOutputStream extends OutputStream A file output stream is an output stream for writing data to aFileor to aFileDescriptor. 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 oneFileOutputStream(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.FileOutputStreamis meant for writing streams of raw bytes such as image data. For writing streams of characters, consider usingFileWriter.- API Note:
- To release resources used by this stream close()should be called directly or by try-with-resources. Subclasses are responsible for the cleanup of resources acquired by the subclass. Subclasses that overridefinalize()in order to perform cleanup should be modified to use alternative cleanup mechanisms such asCleanerand remove the overridingfinalizemethod.
- Implementation Requirements:
- If this FileOutputStream has been subclassed and the close()method has been overridden, theclose()method will be called when the FileInputStream is unreachable. Otherwise, it is implementation specific how the resource cleanup described inclose()is performed.
- Since:
- 1.0
- See Also:
- File,- FileDescriptor,- FileInputStream,- Files.newOutputStream(java.nio.file.Path, java.nio.file.OpenOption...)
 
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Constructor SummaryConstructors Constructor Description FileOutputStream(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.
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Method SummaryAll Methods Instance Methods Concrete Methods Deprecated Methods Modifier and Type Method Description voidclose()Closes this file output stream and releases any system resources associated with this stream.protected voidfinalize()Deprecated, for removal: This API element is subject to removal in a future version.Thefinalizemethod has been deprecated and will be removed.FileChannelgetChannel()Returns the uniqueFileChannelobject associated with this file output stream.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.OutputStreamflush, nullOutputStream
 
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Constructor Detail- 
FileOutputStreampublic FileOutputStream(String name) throws FileNotFoundException Creates a file output stream to write to the file with the specified name. A newFileDescriptorobject is created to represent this file connection.First, if there is a security manager, its checkWritemethod is called withnameas its argument.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
- SecurityException- if a security manager exists and its- checkWritemethod denies write access to the file.
- See Also:
- SecurityManager.checkWrite(java.lang.String)
 
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FileOutputStreampublic FileOutputStream(String name, boolean append) throws FileNotFoundException Creates a file output stream to write to the file with the specified name. If the second argument istrue, then bytes will be written to the end of the file rather than the beginning. A newFileDescriptorobject is created to represent this file connection.First, if there is a security manager, its checkWritemethod is called withnameas its argument.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 name
- append- if- true, 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.
- SecurityException- if a security manager exists and its- checkWritemethod denies write access to the file.
- Since:
- 1.1
- See Also:
- SecurityManager.checkWrite(java.lang.String)
 
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FileOutputStreampublic FileOutputStream(File file) throws FileNotFoundException Creates a file output stream to write to the file represented by the specifiedFileobject. A newFileDescriptorobject is created to represent this file connection.First, if there is a security manager, its checkWritemethod is called with the path represented by thefileargument as its argument.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
- SecurityException- if a security manager exists and its- checkWritemethod denies write access to the file.
- See Also:
- File.getPath(),- SecurityException,- SecurityManager.checkWrite(java.lang.String)
 
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FileOutputStreampublic FileOutputStream(File file, boolean append) throws FileNotFoundException Creates a file output stream to write to the file represented by the specifiedFileobject. If the second argument istrue, then bytes will be written to the end of the file rather than the beginning. A newFileDescriptorobject is created to represent this file connection.First, if there is a security manager, its checkWritemethod is called with the path represented by thefileargument as its argument.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- if- true, 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
- SecurityException- if a security manager exists and its- checkWritemethod denies write access to the file.
- Since:
- 1.4
- See Also:
- File.getPath(),- SecurityException,- SecurityManager.checkWrite(java.lang.String)
 
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FileOutputStreampublic 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.First, if there is a security manager, its checkWritemethod is called with the file descriptorfdObjargument as its argument.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
- Throws:
- SecurityException- if a security manager exists and its- checkWritemethod denies write access to the file descriptor
- See Also:
- SecurityManager.checkWrite(java.io.FileDescriptor)
 
 
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Method Detail- 
writepublic void write(int b) throws IOExceptionWrites the specified byte to this file output stream. Implements thewritemethod ofOutputStream.- Specified by:
- writein class- OutputStream
- Parameters:
- b- the byte to be written.
- Throws:
- IOException- if an I/O error occurs.
 
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writepublic void write(byte[] b) throws IOExceptionWritesb.lengthbytes from the specified byte array to this file output stream.- Overrides:
- writein class- OutputStream
- Parameters:
- b- the data.
- Throws:
- IOException- if an I/O error occurs.
- See Also:
- OutputStream.write(byte[], int, int)
 
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writepublic void write(byte[] b, int off, int len) throws IOExceptionWriteslenbytes from the specified byte array starting at offsetoffto this file output stream.- Overrides:
- writein class- OutputStream
- 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.
 
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closepublic void close() throws IOExceptionCloses 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 interface- AutoCloseable
- Specified by:
- closein interface- Closeable
- Overrides:
- closein class- OutputStream
- API Note:
- Overriding close()to perform cleanup actions is reliable only when called directly or when called by try-with-resources. Do not depend on finalization to invokeclose; finalization is not reliable and is deprecated. If cleanup of native resources is needed, other mechanisms such as Cleaner should be used.
- Throws:
- IOException- if an I/O error occurs.
 
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getFDpublic final FileDescriptor getFD() throws IOException 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:
- FileDescriptor
 
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getChannelpublic FileChannel 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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finalize@Deprecated(since="9", forRemoval=true) protected void finalize() throws IOException Deprecated, for removal: This API element is subject to removal in a future version.Thefinalizemethod has been deprecated and will be removed. Subclasses that overridefinalizein order to perform cleanup should be modified to use alternative cleanup mechanisms and to remove the overridingfinalizemethod. When overriding thefinalizemethod, its implementation must explicitly ensure thatsuper.finalize()is invoked as described inObject.finalize(). See the specification forObject.finalize()for further information about migration options.Cleans up the connection to the file, and ensures that theclose()method of this file output stream is called when there are no more references to this stream. Thefinalize()method does not callclose()directly.- Overrides:
- finalizein class- Object
- API Note:
- To release resources used by this stream close()should be called directly or by try-with-resources.
- Implementation Requirements:
- If this FileOutputStream has been subclassed and the close()method has been overridden, theclose()method will be called when the FileOutputStream is unreachable. Otherwise, it is implementation specific how the resource cleanup described inclose()is performed.
- Throws:
- IOException- if an I/O error occurs.
- See Also:
- FileInputStream.close()
 
 
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