This document discusses Java I/O and serialization. It explains that streams in Java represent an abstraction for input/output and are linked to physical devices. Byte and character streams are defined using input/output stream hierarchies. Object serialization involves writing Java objects to files by converting their state to a byte series. Classes like ObjectInputStream and ObjectOutputStream are used for reading and writing objects. The transient keyword indicates a variable should not be part of an object's persisted state during serialization.

1. JAVA I/O
KIRAN V KULKARNI
ROLL NO: 28 DIV: A
MCA IV SEMESTER
NAVNEET PRAKASH
ROLL NO: 40 DIV: A
MCA IV SEMESTER

2.  It is an abstraction that either produces or consumes
information.
 Stream is linked to a physical device by the Java I/O system.
 A stream is a sequence of data.
 Stream is composed of bytes.
 It's called a stream because it's like a stream of water that
continues to flow.

3.  Java implements streams within class hierarchies
defined in the java.io package.
 Input and Output (I/O) is used to process the input and
produce the output based on the input.
 Java uses the concept of stream to make I/O operations
fast.
 java.io package contains all the classes required for
input and output operations.

5.  Byte streams are defined by using two class hierarchies.
1. Inputstream
2. Outputstream
 Provides convenient means for handling input and
output of bytes.

6. System Class Meaning

7.  Character streams are defined by using two class
hierarchies.
1. Reader
2. Writer
 Character streams provide a convenient means for
handling input and output of characters.

8. Object Serialization
 Serializing objects is the process of writing objects to a file.
 When an object is serialized, its state and other attributes are
converted into an ordered series of bytes.
 This byte series can be written into streams.

9. How to serialize Objects in Java
 Any object whose class implements the java.io.Serializable interface can
be made persistent
import java.io.*;
public class UserData implements Serializable
{
-----member data------
-----member methods-----
}

10. Classes used for Reading and writing objects
 The ObjectInputStream class
 The ObjectOutputStream class
The Classes are found
in
java.io package

11. ObjectOutputStream
Methods
 public void writeObject(Object obj)
 Write the specified object to the ObjectOutputStream.
 public void WriteUTF(String str)
 Primitive data write of this String in UTF format.
 public void flush()
 Flushes the stream
 public void close()
 Closes the stream

16. Introduction to Transient variables
 You use the transient keyword to indicate to the Java virtual machine
that the indicated variable is not part of the persistent state of the
object.
 Variables that are part of the persistent state of an object must be
saved when the object is archived
class MyData implements Serializable
{String name;
transient int age;
---constructor to enterdata
}

17. Summary (Contd.)
• Serialization allows reducing time taken to write code for
save and restoration of object or application state
• Serialization makes it easier for objects to travel over a
network connection.
• Transient Variables are not persisted.