Multithreading is the ability of a program or an operating system process to manage its use by more than one user at a time and to even manage multiple requests by the same user without having to have multiple copies of the programming running in the computer.

1. Multithreading
M. Raihan
Computer Science and Engineering Discipline , Khulna University

2. What is Thread ?
 A thread is similar to a program that has a single flow of control
 A thread has a beginning , a body and an end and executes commands
sequentially.
 Each thread is a statically ordered sequence of
instructions.
 Threads are being extensively used express concurrency on both single and
multiprocessors machines.

3. What is Multithread?
Multithreading is the ability of a program or an
operating system process to manage its use by
more than one user at a time and to even manage
multiple requests by the same user without
having to have multiple copies of the
programming running in the computer.

4. A Single Thread

5. A Multithread Program

6. Threads Methods
 Java has built in thread support for Multithreading
 Thread Methods :

7. Thread Declaration
Thread can be declared in two ways :
 Create a class that extends the Thread class
 Create a class that implements the Runnable interface

8. 1st way:
 Create a class by extending Thread class and override
run() method:
class MyThread extends Thread
{
public void run()
{
// thread body of execution
}
}
Create a thread:
MyThread thr1 = new MyThread();
Start Execution of threads:
thr1.start();
Create and Execute:
new MyThread().start();

9. 2nd way:
 Create a class that implements the interface Runnable
and override run() method:
class MyThread implements Runnable
{
.....
public void run()
{
// thread body of execution
}
}
Creating Object:
MyThread myObject = new MyThread();
Creating Thread Object:
Thread thr1 = new Thread( myObject );
Start Execution:
thr1.start();

10. Life Circle

11. Synchronization
 Synchronization in java is the capability of control the access of
multiple threads to any shared resource.
 Java Synchronization is better option where we want to allow only one
thread to access the shared resource.
 Why we use :
1. To prevent thread interference.
2. To prevent consistency problem.

12. Synchronization
 Synchronization in java is the capability of control the access of multiple threads to
any shared resource.
 Java Synchronization is better option where we want to allow only one thread to
access the shared resource.
 Why we use :
1. To prevent thread interference.
2. To prevent consistency problem.
Synchronized method is used to lock an object for any shared resource.

13. Example
class Table{
synchronized void printTable(int n){//synchronized method
for(int i=1;i<=5;i++){
System.out.println(n*i);
try{
Thread.sleep(400);
}catch(Exception e){System.out.println(e);}
}
}
}

14. Example (Continue)
class MyThread1 extends Thread{
Table t;
MyThread1(Table t){
this.t=t;
}
public void run(){
t.printTable(2);
}
}
class MyThread2 extends Thread{
Table t;
MyThread2(Table t){
this.t=t;
}
public void run(){
t.printTable(100);
}
}

15. Example (Continue)
public class TestSynchronization{
public static void main(String args[]){
Table obj = new Table();//only one object
MyThread1 t1=new MyThread1(obj);
MyThread2 t2=new MyThread2(obj);
t1.start();
t2.start();
}
}

16. Thank You