Closeable, Flushable, AutoCloseable
public class FileOutputStream extends OutputStream
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.
close() method should be called to release resources used by this stream, either directly, or with the try-with-resources statement.Cleaner or some other mechanism.| Constructor | Description |
|---|---|
FileOutputStream |
Creates a file output stream to write to the file represented by the specified File object. |
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. |
FileOutputStream |
Creates a file output stream to write to the file represented by the specified File object. |
FileOutputStream |
Creates a file output stream to write to the file with the specified name. |
FileOutputStream |
Creates a file output stream to write to the file with the specified name. |
| Modifier and Type | Method | Description |
|---|---|---|
void |
close() |
Closes this file output stream and releases any system resources associated with this stream. |
FileChannel |
getChannel() |
Returns the unique FileChannel object associated with this file output stream. |
final FileDescriptor |
getFD() |
Returns the file descriptor associated with this stream. |
void |
write |
Writes b.length bytes from the specified byte array to this file output stream. |
void |
write |
Writes len bytes from the specified byte array starting at offset off to this file output stream. |
void |
write |
Writes the specified byte to this file output stream. |
flush, nullOutputStream
public FileOutputStream(String name) throws FileNotFoundException
FileDescriptor object is created to represent this file connection. First, if there is a security manager, its checkWrite method is called with name 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 FileNotFoundException is thrown.
name is equivalent to invoking new FileOutputStream(name, false).name - the system-dependent filenameFileNotFoundException - 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 reasonSecurityException - if a security manager exists and its checkWrite method denies write access to the file.public FileOutputStream(String name, boolean append) throws FileNotFoundException
true, then bytes will be written to the end of the file rather than the beginning. A new FileDescriptor object is created to represent this file connection. First, if there is a security manager, its checkWrite method is called with name 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 FileNotFoundException is thrown.
name - the system-dependent file nameappend - if true, then bytes will be written to the end of the file rather than the beginningFileNotFoundException - 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 checkWrite method denies write access to the file.public FileOutputStream(File file) throws FileNotFoundException
File object. A new FileDescriptor object is created to represent this file connection. First, if there is a security manager, its checkWrite method is called with the path represented by the file argument 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 FileNotFoundException is thrown.
file - the file to be opened for writing.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 reasonSecurityException - if a security manager exists and its checkWrite method denies write access to the file.public FileOutputStream(File file, boolean append) throws FileNotFoundException
File object. If the second argument is true, then bytes will be written to the end of the file rather than the beginning. A new FileDescriptor object is created to represent this file connection. First, if there is a security manager, its checkWrite method is called with the path represented by the file argument 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 FileNotFoundException is thrown.
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 beginningFileNotFoundException - 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 reasonSecurityException - if a security manager exists and its checkWrite method denies write access to the file.public FileOutputStream(FileDescriptor fdObj)
First, if there is a security manager, its checkWrite method is called with the file descriptor fdObj argument as its argument.
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.
fdObj - the file descriptor to be opened for writingSecurityException - if a security manager exists and its checkWrite method denies write access to the file descriptorpublic void write(int b) throws IOException
write method of OutputStream.write in class OutputStream
b - the byte to be written.IOException - if an I/O error occurs.public void write(byte[] b) throws IOException
b.length bytes from the specified byte array to this file output stream.write in class OutputStream
b - the data.IOException - if an I/O error occurs.public void write(byte[] b, int off, int len) throws IOException
len bytes from the specified byte array starting at offset off to this file output stream.write in class OutputStream
b - the data.off - the start offset in the data.len - the number of bytes to write.IOException - if an I/O error occurs.IndexOutOfBoundsException - If off is negative, len is negative, or len is greater than b.length - off
public void close() throws IOException
If this stream has an associated channel then the channel is closed as well.
close in interface AutoCloseable
close in interface Closeable
close in class OutputStream
close() to perform cleanup actions is reliable only when called directly or when called by try-with-resources.Cleaner mechanism. 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.
IOException - if an I/O error occurs.public final FileDescriptor getFD() throws IOException
FileDescriptor object that represents the connection to the file in the file system being used by this FileOutputStream object.IOException - if an I/O error occurs.public FileChannel getChannel()
FileChannel object associated with this file output stream. The initial position of 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.
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