Package java.io

Class FileOutputStream

java.lang.Object
java.io.OutputStream
java.io.FileOutputStream
All Implemented Interfaces:
Closeable, Flushable, AutoCloseable
public class FileOutputStream
extends OutputStream
An output stream that writes bytes to a file. If the output file exists, it can be replaced or appended to. If it does not exist, a new file will be created. 
   
   File file = ...
   OutputStream out = null;
   try {
     out = new BufferedOutputStream(new FileOutputStream(file));
     ...
   } finally {
     if (out != null) {
       out.close();
     }
   }

This stream is not buffered. Most callers should wrap this stream with a BufferedOutputStream.

Use FileWriter to write characters, as opposed to bytes, to a file.

See Also:
BufferedOutputStream, FileInputStream

  • Constructor Details

    • FileOutputStream

      public FileOutputStream​(File file) throws FileNotFoundException
      Constructs a new FileOutputStream that writes to file. The file will be truncated if it exists, and created if it doesn't exist.
      Throws:
      FileNotFoundException - if file cannot be opened for writing.

    • FileOutputStream

      public FileOutputStream​(File file, boolean append) throws FileNotFoundException
      Constructs a new FileOutputStream that writes to file. If append is true and the file already exists, it will be appended to; otherwise it will be truncated. The file will be created if it does not exist.
      Throws:
      FileNotFoundException - if the file cannot be opened for writing.

    • FileOutputStream

      public FileOutputStream​(FileDescriptor fd)
      Constructs a new FileOutputStream that writes to fd.
      Throws:
      NullPointerException - if fd is null.

    • FileOutputStream

      public FileOutputStream​(String path) throws FileNotFoundException
      Constructs a new FileOutputStream that writes to path. The file will be truncated if it exists, and created if it doesn't exist.
      Throws:
      FileNotFoundException - if file cannot be opened for writing.

    • FileOutputStream

      public FileOutputStream​(String path, boolean append) throws FileNotFoundException
      Constructs a new FileOutputStream that writes to path. If append is true and the file already exists, it will be appended to; otherwise it will be truncated. The file will be created if it does not exist.
      Throws:
      FileNotFoundException - if the file cannot be opened for writing.

  • Method Details

    • close

      public void close() throws IOException
      Description copied from class: OutputStream
      Closes this stream. Implementations of this method should free any resources used by the stream. This implementation does nothing.
      Specified by:
      close in interface AutoCloseable
      Specified by:
      close in interface Closeable
      Overrides:
      close in class OutputStream
      Throws:
      IOException - if an error occurs while closing this stream.

    • finalize

      protected void finalize() throws IOException
      Description copied from class: Object
      Invoked when the garbage collector has detected that this instance is no longer reachable. The default implementation does nothing, but this method can be overridden to free resources.

      Note that objects that override finalize are significantly more expensive than objects that don't. Finalizers may be run a long time after the object is no longer reachable, depending on memory pressure, so it's a bad idea to rely on them for cleanup. Note also that finalizers are run on a single VM-wide finalizer thread, so doing blocking work in a finalizer is a bad idea. A finalizer is usually only necessary for a class that has a native peer and needs to call a native method to destroy that peer. Even then, it's better to provide an explicit close method (and implement Closeable), and insist that callers manually dispose of instances. This works well for something like files, but less well for something like a BigInteger where typical calling code would have to deal with lots of temporaries. Unfortunately, code that creates lots of temporaries is the worst kind of code from the point of view of the single finalizer thread.

      If you must use finalizers, consider at least providing your own ReferenceQueue and having your own thread process that queue.

      Unlike constructors, finalizers are not automatically chained. You are responsible for calling super.finalize() yourself.

      Uncaught exceptions thrown by finalizers are ignored and do not terminate the finalizer thread. See Effective Java Item 7, "Avoid finalizers" for more.

      Overrides:
      finalize in class Object
      Throws:
      IOException

    • getChannel

      public FileChannel getChannel()
      Returns a write-only FileChannel that shares its position with this stream.

    • getFD

      public final FileDescriptor getFD() throws IOException
      Returns the underlying file descriptor.
      Throws:
      IOException

    • write

      public void write​(byte[] buffer, int byteOffset, int byteCount) throws IOException
      Description copied from class: OutputStream
      Writes count bytes from the byte array buffer starting at position offset to this stream.
      Overrides:
      write in class OutputStream
      Parameters:
      buffer - the buffer to be written.
      byteOffset - the start position in buffer from where to get bytes.
      byteCount - the number of bytes from buffer to write to this stream.
      Throws:
      IOException - if an error occurs while writing to this stream.

    • write

      public void write​(int oneByte) throws IOException
      Description copied from class: OutputStream
      Writes a single byte to this stream. Only the least significant byte of the integer oneByte is written to the stream.
      Specified by:
      write in class OutputStream
      Parameters:
      oneByte - the byte to be written.
      Throws:
      IOException - if an error occurs while writing to this stream.