ObjectOutputStream class

ObjectOutput interface

The ObjectOutput interface extends the DataOutput interface and supports object serialization. It defines the methods shown in the following table:

void close( )

Closes the invoking stream.

void flush( )

Flushes the output buffers.

void write(byte buffer[ ])

Writes an array of bytes to the invoking stream.

void write(byte buffer[ ], int offset, int numBytes)

Writes a subrange of numBytes bytes from the array buffer, beginning at buffer[offset].

void write(int b)

Writes a single byte to the invoking stream. The byte written is the low-order byte of b.

void writeObject(Object obj)

Writes object obj to the invoking stream.

ObjectOutputStream class

The ObjectOutputStream class extends the OutputStream class and implements the ObjectOutput interface. It is responsible for writing objects to a stream.

A constructor of this class is

ObjectOutputStream(OutputStream outStream) throws IOException

outStream is the output stream to which serialized objects will be written.

void close( )

Closes the invoking stream.

void flush( )

Flushes the output buffers.

void write(byte buffer[ ])

Writes an array of bytes to the invoking stream.

void write(byte buffer[ ], int offset, int numBytes)

Writes a subrange of numBytes bytes from the array buffer, beginning at buffer[offset].

void write(int b)

Writes a single byte to the invoking stream. The byte written is the low-order byte of b.

void writeBoolean(boolean b)

Writes a boolean to the invoking stream.

void writeByte(int b)

Writes a byte to the invoking stream. The byte written is the low-order byte of b.

void writeBytes(String str)

Writes the bytes representing str to the invoking stream.

void writeChar(int c)

Writes a char to the invoking stream.

void writeChars(String str)

Writes the characters in str to the invoking stream.

void writeDouble(double d)

Writes a double to the invoking stream.

void writeFloat(float f )

Writes a float to the invoking stream.

void writeInt(int i)

Writes an int to the invoking stream.

void writeLong(long l)

Writes a long to the invoking stream.

final void writeObject(Object obj)

Writes obj to the invoking stream.

void writeShort(int i)

Writes a short to the invoking stream.

Revised from Open JDK source code

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.util.Date;

public class Main {
  public static void main(String args[]) throws IOException {
    FileOutputStream fos = new FileOutputStream("t.tmp");
    ObjectOutputStream oos = new ObjectOutputStream(fos);

    oos.writeInt(12345);
    oos.writeObject("Today");
    oos.writeObject(new Date());

    oos.close();

  }
}