ObjectOutputStream class methods in Java

java.io.ObjectOutputStream

An ObjectOutputStream writes primitive data types and graphs of Java objects to an OutputStream. The objects can be read using an ObjectInputStream.

Persistent storage of objects can be accomplished by using a file for the stream. If the stream is a network socket stream, the objects can be reconstituted on another host or in another process.

The method writeObject is used to write an object to the stream. Any object, including Strings and arrays, is written with writeObject. Multiple objects or primitives can be written to the stream. The objects must be read back from the corresponding ObjectInputstream with the same types and in the same order as they were written.

Primitive data types can also be written to the stream using the appropriate methods from DataOutput. Strings can also be written using the writeUTF method.

Some methods of ObjectOutputStream class

close(): This method must be called to release any resources associated with the stream.

defaultWriteObject(): This method writes the non-static and non-transient fields of the current class to this stream.

flush(): This method flushes the stream.

putFields(): This method retrieves the object used to buffer persistent fields to be written to the stream.

reset(): The state is reset to be the same as a new ObjectOutputStream.

useProtocolVersion(int): This method specifies the stream protocol version to use when writing the stream.

write(byte[]): This method writes an array of bytes. 

write(int): This method writes a byte.

write(byte[], int, int): This method writes a sub array of bytes.

writeBoolean(boolean): This method writes a boolean.

writeByte(int): This method writes an 8-bit byte.

writeBytes(String): This method writes a String as a sequence of bytes.

writeChar(int): This method writes a 16-bit char.

writeChars(String): This method writes a String as a sequence of chars.

writeDouble(double): This method writes a 64-bit double.

writeFields(): This method writes the buffered fields to the stream.

writeFloat(float): This method writes a 32-bit float.

writeInt(int): This method writes a 32-bit int.

writeLong(long): This method writes a 64-bit long.

writeObject(Object): This method writes the specified object to the ObjectOutputStream.

writeShort(int): This method writes a 16-bit short.

writeUnshared(Object): This method writes an "unshared" object to the ObjectOutputStream.

writeUTF(String): This method is primitive data are written of this String in modified UTF-8 format.