Java I/O and Object Serialization
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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.
Java I/O and Object 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.
- 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.