1. Java Basics
Introduction to Streams

2. Topics To Be Covered Objectives Introduction to Streams
Object Serialization
Summary
Quiz

3. Objectives Write programs using Byte Streams Serialize Objects
At the end of this course,
you will be able to:
Write programs using Byte Streams
Serialize Objects
Write programs using Character Streams

4. Streams

5. Streams Files are used for Store Java classes, programs
Store pictures, music, videos
Can also use files to store program I/O
A stream is a flow of input or output data
Characters
Numbers
Bytes

6. Streams Key board input is a temporary data .
When we close the program the data is vanished .
But we can save that data in files for future use .
It may be used for this program next time.
It may be use in another program.
Input stream
Output stream
Keyboard
Monitor
Input stream
Output stream
Hard disc
Compact disc

7. Streams There are two types of files used in file programming :
Binary files
All data stored in the form of zero’s and one’s
Movies, music and same files are binary files
Text files
It can be viewed by text editor and may also be edited .

8. Streams A text file and binary file having same values. 1 2 3 4 5 - 77 8
A binary file
12345
-4027 8

9. Streams
Output stream
Output stream is used to write data in a file or array .
Input stream
Input stream is used to read data from the source.

10. Streams How do we take an input from keyboard?
Input Streams are used to read data from any data source like keyboard, socket, file etc.
Output Streams are used to write data to any data destination like console, socket, file etc.

11. Streams What is an I/O Stream?
An abstract representation of data connected to some input or output device is called as Stream
Java Program { … }
InputStream
File.txt
OutputStream

12. Streams Two Types of Stream Classes: Byte Stream Character Stream
Usually works for bytes & binary objects
InputStreais and OutputStream are the abstract classes which represent Byte Streams
Character Stream
Usually works for Characters & Strings
Follows the Unicode
Introduced to cater to the needs of internationalization
Reader and writer are the abstract classes which represents Character Streams

13. Streams May be buffered or unbuffered I/O Streams
Byte Oriented Streams
InputStream
FileInputStream, DataInputStream
OutputStream
FileOutputStream, DataOutputStream
Unicode Character Oriented Streams
Reader
InputStreamReader
FileReader
OutputStreamWriter
FileWriter
Writer
Streams
Abstract Classes
May be buffered or unbuffered

14. Streams Byte Streams FileOutputStream & FilelnputStream classes:
These are sub classes of OutPutStream and InPutStream Classes respectively
These are used to write & read binary data and /or binary object to and from the data source
FileOutputStream fos = new FileOutputStream (“abc.txt”);
FilelnputStream fis = new FileInputStream (“abc.txt”);

15. read() returns -1 on encountering end of file
Streams
Byte Streams
import java.io.*;
public class ReadWriteFile {
public static void main(String args[]) {
try {
FilelnputStream fis = new FilelnputStream(“Source.txt");
FileOutputStream fos = new FileOutputStream(“Dest.txt");
int nextByte ;
while((nextByte = fis.read()) != -1) {
fos.write((char)nextByte);
System.out.println(nextByte); }
fis.close();
fos.close();
catch (IOException e) {
System.out.println("Error reading file" + e );
FilelnputStream object is used to read data from the file
FileOutputStream object is used to write data to a file
read() returns -1 on encountering end of file

16. Streams BufferedlnputStream & Buf feredOuputStream classes:
Subclasses of InputStream & OutputStream classes respectively
We can wrap a BufferedlnputStream around the FilelnputStream for reading and storing large chunks of data in a buffer at once for later use
Java Program { … }
BufferedInputStream
File
FileInputStream
Internal Buffer
We can then read data from the BufferedlnputStream.
Data is read from the buffer instead of directly from the file on each read
The BufferedlnputStream reads data from the File in large chunks and stores the data in an internal buffer

17. Streams BufferedlnputStream adds buffering to FilelnputStream object
import java.io.*;
public class BufferedDemo {
public static void main(String[] args) {
try {
Bufferedlnputstream bufferedFile = new Bufferedlnputstream(
new Filelnputstream(“Source.txt"));
int nextByte;
while ((nextByte = bufferedFile.read()) != -1) {
System.out.print((char)nextByte); }
} catch (IOException e) {
System.out.println("Error reading file" + e);

18. Streams Data I/O Streams
We may want an even higher level of abstraction and wish to read and write data to and from streams in the form of primitive data variables (rather than just bytes or characters)
Java has built in stream classes to automatically handle converting this information into the necessary raw bytes that a stream can use

19. Streams DatalnputStream & DataOutputStream classes:
import java.io.*;
public class DataStream {
public static void main(String[] args) {
try {
BufferedOutputStream bos = new BufferedOutputStream
(new FileOutputStream("Number.txt”));
DataOutputStream dos = new DataOutputStream(bos);
dos.writelnt(5);
dos.close();
bos.close();
BufferedlnputStream bis = new BufferedlnputStream
(new FileInputStream("Number.txt"));
DatalnputStream dis = new DatalnputStream(bis);
int n = dis.readInt();
System.out.println("Number in File is...” + n);
dis.close();
bis.close(); }
catch(IOException e) {
System.out.println("Error writing to file” + e );
DatalnputStream & DataOutputStream classes:
Allow to read and write primitive data types to input and output streams respectively

20. Streams Character Streams Two types of Character Stream classes:
Reader
Writer
FileReader and Filewriter classes:
Subclasses of Reader & writer class
Used to read and write characters or strings from a data source like file
Filewriter fw = new Filewriter("abc.txt",true);
FileReader fr = new FileReader(“abc.txt");

21. Streams BufferedReader & BufferedWriter classes:
Provides buffering to Character streams
Subclasses of Reader & writer classes
BufferedReader is used to read data from console & files
InputStreamReader class:
Serves as a wrapper for any InputStream object
Converts the raw bytes as they are read from the InputStream and serves them to the user as Unicode characters

22. Streams Reading data from console:
We can wrap InputStreamReaders around InputStreams to make them useful In reading character data
BufferedReader provides a readLine() method for additional functionality
BufferedReader stdin = new BufferedReader (new
InputStreamReader(Systeni.in));
try {
String input = stdin.readline();
System.out.println("The input from the command line was " + input);
} catch(IOException e) {
System.err.println("Error reading data"); }

23. Common method used in output stream class
Description
1) public void write(int)throws IOException:
is used to write a byte to the current output stream.
2) public void write(byte[])throws IOException:
is used to write an array of byte to the current output stream.
3) public void flush()throws IOException:
flushes the current output stream.
4) public void close()throws IOException:
is used to close the current output stream.

24. Common method used in input stream class
Description
1) public abstract int read()throws IOException:
reads the next byte of data from the input stream.It returns -1 at the end of file.
2) public int available()throws IOException:
returns an estimate of the number of bytes that can be read from the current input stream.
3) public void close()throws IOException:
is used to close the current input stream.

25. Example of Java FileOutputStream class
import java.io.*;  
class Test{  
  public static void main(String args[]){  
   try{  
     FileOutputstream fout=new FileOutputStream("abc.txt");  
     String s=“This is file output stream";  
     byte b[]=s.getBytes(); //converting string into byte array  
     fout.write(b);  
     fout.close();  
     System.out.println("success...");  
    }catch(Exception e){system.out.println(e);}  
  }  
}  

26. Example of Java FileInputStream class
import java.io.*;  
class SimpleRead{  
 public static void main(String args[]){  
  try{  
    FileInputStream fin=new FileInputStream("abc.txt");  
    int i=0;  
    while((i=fin.read())!=-1){  
     System.out.println((char)i);  
    }  
    fin.close();  
  }catch(Exception e){system.out.println(e);}  
 }   } 

27. Object Serialization

28. Object Serialization
The process of writing the state of an object to a byte stream
Saves the state of an Object to any data destination like file
This may later be restored by the process of Deserialization
Only an object that implements the Serilizable interface can be saved and restored by the serilization facilities
The Serializable interface defines no members: It is simply used to indicate that a class may be serialized
All subclasses of a serializable class are also serializable

29. Object Serialization ObjectOutputStream & ObjectlnputStream classe
Subclasses of InputStream & OutputStream classes
Same functionality as DatalnputStream & DataOutputStream
Also includes support for reading and writing objects data via the readObject() & writeObject() methods
Employee e1 = new Employee(12345, "Bipin Kabra");
ObjectOutputStream oos = new 0bject0utputstream(
new FileOutputStream("Emp.txt”));
oos.writeobject(el);
Employee e2 ;
ObjectlnputStream ois = new ObjectlnputStream(
new FilelnputStream("Emp.txt"));
e2 = (Employee) ois.readObject();

30. Object Serialization Serialization Example
public class Employee implements Serializable{
private int empNo;
private String eName;
public Employee(int empNo, String eName) { this.empNo = empNo;
this.eName = eName; }
public int getEmpNo() {
return empNo;
public String getEName() {
return eName;

31. Object Serialization Serialization Example www.prolearninghub.com
import java.io.* ;
public class SerializationDemo {
public static void main(String[] args) {
try{
Employee el = new Employee(1234, "Bhushan”);
ObjectOutputStream oos = new ObjectOutputStream(
new FileOutputStream("Emp.txt“));
oos.writeObject(el);
Employee e2 ;
ObjectlnputStream ois = new ObjectInputStream(
new FileInputStream("Emp.txt“));
e2 = (Employee) ois.readObject();
System.out.println(e2.getEmpNo()+ “ ”+ e2.getEName()); }
catch(Exception e){
System.out.printIn(e);

32. Summary In this session, we have covered: What is an I/O Stream?
Types of Streams
Byte Streams
Object Serialization
Character Streams

33. Assessment – Java Basics: Part 4
The quiz contains 10 questions.
You will have one attempt to answer each question.
You can exit the quiz at any time.
If you exit the quiz without completing all 10 questions, on return you will have to start the quiz from the beginning.
Scoring 80% or higher means you have understood the topic well.
Start

34. For writing state of an object, which method is used?
readObject()
storeObject()
writeObject()

35. Which class you will use for reading and storing large chunks of data in a buffer?
BufferedInputStream
FileInputStream
FileOutputStream

36. Which of the following class allows to red primitive data?
FileOutputStream
DataInputStream
FileInputStream

37. For reading the state of an object, which method is used?
readObject()
storeObject()
writeObject()

38. Serialization is process of writing state of an object to a destination?
True
False

39. Which stream is used to write data to any destination?
Input
Output
InputOutput

40. All subclasses of a serializable class are not serializable?
True
False

41. Which of the following is not an abstract class in stream family?
DataInputStream
InputStream
OutputStream

42. The class whose state you want to write to a destination must interface?
Serializable
Externizable
Storable

43. Find the odd one from following.
Byte Steam
Character Steam
Bit Steam

44. The Results