FileImageOutputStream (Java Platform SE 8 )
Keywords: javax.imageio.stream.FileImageOutputStream class
Date: 2026-04-17

javax.imageio.stream

## Class FileImageOutputStream

- java.lang.Object
- - javax.imageio.stream.ImageInputStreamImpl
  - - javax.imageio.stream.ImageOutputStreamImpl
    - - javax.imageio.stream.FileImageOutputStream

- All Implemented Interfaces:
    Closeable, DataInput, DataOutput, AutoCloseable, ImageInputStream, ImageOutputStream

      public class FileImageOutputStream
      extends ImageOutputStreamImpl

  An implementation of `ImageOutputStream` that writes its output directly to a `File` or `RandomAccessFile`.

- - ### Field Summary

    - ### Fields inherited from class javax.imageio.stream.ImageInputStreamImpl

      `bitOffset, byteOrder, flushedPos, streamPos`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `FileImageOutputStream(File f)` Constructs a `FileImageOutputStream` that will write to a given `File`.
    `FileImageOutputStream(RandomAccessFile raf)` Constructs a `FileImageOutputStream` that will write to a given `RandomAccessFile`.

  - ### Method Summary

    All Methods Instance Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `close()` Closes the stream.
    `protected void` | `finalize()` Finalizes this object prior to garbage collection.
    `long` | `length()` Returns `-1L` to indicate that the stream has unknown length.
    `int` | `read()` Reads a single byte from the stream and returns it as an `int` between 0 and 255.
    `int` | `read(byte[] b, int off, int len)` Reads up to `len` bytes from the stream, and stores them into `b` starting at index `off`.
    `void` | `seek(long pos)` Sets the current stream position and resets the bit offset to 0.
    `void` | `write(byte[] b, int off, int len)` Writes a sequence of bytes to the stream at the current position.
    `void` | `write(int b)` Writes a single byte to the stream at the current position.

    - ### Methods inherited from class javax.imageio.stream.ImageOutputStreamImpl

      `flushBits, write, writeBit, writeBits, writeBoolean, writeByte, writeBytes, writeChar, writeChars, writeChars, writeDouble, writeDoubles, writeFloat, writeFloats, writeInt, writeInts, writeLong, writeLongs, writeShort, writeShorts, writeUTF`

    - ### Methods inherited from class javax.imageio.stream.ImageInputStreamImpl

      `checkClosed, flush, flushBefore, getBitOffset, getByteOrder, getFlushedPosition, getStreamPosition, isCached, isCachedFile, isCachedMemory, mark, read, readBit, readBits, readBoolean, readByte, readBytes, readChar, readDouble, readFloat, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedInt, readUnsignedShort, readUTF, reset, setBitOffset, setByteOrder, skipBytes, skipBytes`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

    - ### Methods inherited from interface javax.imageio.stream.ImageOutputStream

      `flushBefore`

    - ### Methods inherited from interface javax.imageio.stream.ImageInputStream

      `flush, getBitOffset, getByteOrder, getFlushedPosition, getStreamPosition, isCached, isCachedFile, isCachedMemory, mark, read, readBit, readBits, readBoolean, readByte, readBytes, readChar, readDouble, readFloat, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedInt, readUnsignedShort, readUTF, reset, setBitOffset, setByteOrder, skipBytes, skipBytes`

- - ### Constructor Detail

    - #### FileImageOutputStream

          public FileImageOutputStream(File f)
                                throws FileNotFoundException,
                                       IOException

      Constructs a `FileImageOutputStream` that will write to a given `File`.
      Parameters:
        `f` - a `File` to write to.
      Throws:
        `IllegalArgumentException` - if `f` is `null`.
        `SecurityException` - if a security manager exists and does not allow write access to the file.
        `FileNotFoundException` - if `f` does not denote a regular file or it cannot be opened for reading and writing for any other reason.
        `IOException` - if an I/O error occurs.

    - #### FileImageOutputStream

          public FileImageOutputStream(RandomAccessFile raf)

      Constructs a `FileImageOutputStream` that will write to a given `RandomAccessFile`.
      Parameters:
        `raf` - a `RandomAccessFile` to write to.
      Throws:
        `IllegalArgumentException` - if `raf` is `null`.

  - ### Method Detail

    - #### read

          public int read()
                   throws IOException

      Description copied from class: `ImageInputStreamImpl`
      Reads a single byte from the stream and returns it as an `int` between 0 and 255. If EOF is reached, `-1` is returned.

      Subclasses must provide an implementation for this method. The subclass implementation should update the stream position before exiting.

      The bit offset within the stream must be reset to zero before the read occurs.

      Specified by:
        `read` in interface `ImageInputStream`
      Specified by:
        `read` in class `ImageInputStreamImpl`
      Returns:
        the value of the next byte in the stream, or `-1` if EOF is reached.
      Throws:
        `IOException` - if the stream has been closed.

    - #### read

          public int read(byte[] b,
                          int off,
                          int len)
                   throws IOException

      Description copied from class: `ImageInputStreamImpl`
      Reads up to `len` bytes from the stream, and stores them into `b` starting at index `off`. If no bytes can be read because the end of the stream has been reached, `-1` is returned.

      The bit offset within the stream must be reset to zero before the read occurs.

      Subclasses must provide an implementation for this method. The subclass implementation should update the stream position before exiting.

      Specified by:
        `read` in interface `ImageInputStream`
      Specified by:
        `read` in class `ImageInputStreamImpl`
      Parameters:
        `b` - an array of bytes to be written to.
        `off` - the starting position within `b` to write to.
        `len` - the maximum number of bytes to read.
      Returns:
        the number of bytes actually read, or `-1` to indicate EOF.
      Throws:
        `IOException` - if an I/O error occurs.

    - #### write

          public void write(int b)
                     throws IOException

      Description copied from interface: `ImageOutputStream`
      Writes a single byte to the stream at the current position. The 24 high-order bits of `b` are ignored.

      If the bit offset within the stream is non-zero, the remainder of the current byte is padded with 0s and written out first. The bit offset will be 0 after the write. Implementers can use the `flushBits` method of `ImageOutputStreamImpl` to guarantee this.

      Specified by:
        `write` in interface `DataOutput`
      Specified by:
        `write` in interface `ImageOutputStream`
      Specified by:
        `write` in class `ImageOutputStreamImpl`
      Parameters:
        `b` - an `int` whose lower 8 bits are to be written.
      Throws:
        `IOException` - if an I/O error occurs.

    - #### write

          public void write(byte[] b,
                            int off,
                            int len)
                     throws IOException

      Description copied from interface: `ImageOutputStream`
      Writes a sequence of bytes to the stream at the current position. If `len` is 0, nothing is written. The byte `b[off]` is written first, then the byte `b[off + 1]`, and so on.

      If the bit offset within the stream is non-zero, the remainder of the current byte is padded with 0s and written out first. The bit offset will be 0 after the write. Implementers can use the `flushBits` method of `ImageOutputStreamImpl` to guarantee this.

      Specified by:
        `write` in interface `DataOutput`
      Specified by:
        `write` in interface `ImageOutputStream`
      Specified by:
        `write` in class `ImageOutputStreamImpl`
      Parameters:
        `b` - an array of `byte`s to be written.
        `off` - the start offset in the data.
        `len` - the number of `byte`s to write.
      Throws:
        `IOException` - if an I/O error occurs.

    - #### length

          public long length()

      Description copied from class: `ImageInputStreamImpl`
      Returns `-1L` to indicate that the stream has unknown length. Subclasses must override this method to provide actual length information.
      Specified by:
        `length` in interface `ImageInputStream`
      Overrides:
        `length` in class `ImageInputStreamImpl`
      Returns:
        -1L to indicate unknown length.

    - #### seek

          public void seek(long pos)
                    throws IOException

      Sets the current stream position and resets the bit offset to 0. It is legal to seeking past the end of the file; an `EOFException` will be thrown only if a read is performed. The file length will not be increased until a write is performed.
      Specified by:
        `seek` in interface `ImageInputStream`
      Overrides:
        `seek` in class `ImageInputStreamImpl`
      Parameters:
        `pos` - a `long` containing the desired file pointer position.
      Throws:
        `IndexOutOfBoundsException` - if `pos` is smaller than the flushed position.
        `IOException` - if any other I/O error occurs.

    - #### close

          public void close()
                     throws IOException

      Description copied from interface: `ImageInputStream`
      Closes the stream. Attempts to access a stream that has been closed may result in `IOException`s or incorrect behavior. Calling this method may allow classes implementing this interface to release resources associated with the stream such as memory, disk space, or file descriptors.
      Specified by:
        `close` in interface `Closeable`
      Specified by:
        `close` in interface `AutoCloseable`
      Specified by:
        `close` in interface `ImageInputStream`
      Overrides:
        `close` in class `ImageInputStreamImpl`
      Throws:
        `IOException` - if an I/O error occurs.

    - #### finalize

          protected void finalize()
                           throws Throwable

      Finalizes this object prior to garbage collection. The `close` method is called to close any open input source. This method should not be called from application code.
      Overrides:
        `finalize` in class `ImageInputStreamImpl`
      Throws:
        `Throwable` - if an error occurs during superclass finalization.
      See Also:
        `WeakReference`, `PhantomReference`

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