28, మార్చి 2012, బుధవారం

MULTI THREADING CONCEPTS AND ITS IMPLEMENTATION IN JAVA


Threads:-
-          A thread represents a process or Execution
//PROGRAM-1find out the currently running thread
class Current
{
public static void main(String args[])
{
System.out.println("this is first line");
Thread t = Thread.currentThread();
System.out.println(t);
System.out.println("Name = " + t.getName());
}
}
In every java program the default is main thread
The purpose of thread is to execute the statements one by one.
Executing the statements is of two types
1)      single tasking
2)      Multi tasking
1)      Single tasking:-
         Single tasking execute only one job at a time by the processor is called single tasking.
2)      Multi tasking:-
          Executing several tasks simultaneously is called multitasking.
Time slicing:-
   The part of the time allotted for each job by Microprocessor.
Round Robin Method:-
            The microprocessor goes to the first job after it has executed the last job , in a cyclic manner is called round robin method.
Processed based Multitasking:-
     Executing several programs at a time is called process based Multi tasking.
Thread based Multitasking:-
       Executing different parts of the same program with the help of threads is called thread based multitasking.
Multithreading:-
         Using more than one thread is called Multithreading
Threads are light weight process.
IIQ) why thread is called lightweight process?
A thread is a lightweight process it uses less resources of the system.

Uses of threads:-
1)      Threads are used at server side programs to handle multiple clients.
2)      Threads are used in Animation and games.

Creating a Thread:-
1.      write a class that extends Thread class or implements runnable Interface.
2.      Thread a runnable interface in java.lang package
3.      write public void run() methods inside that class
     note:- A thread can execute the statements of run method only.
4.      create an object to the class
5.      create a thread and attach the thread to that object
6.      thread t = new thread( obj , ”threadname”);
7.      Run the thread on the object.

//creating a thread and running it.
class Myclass extends Thread
{
boolean stop = false;
public void run()
{
for(int i=1;i<100000;i++)
{
System.out.println(i);
if(stop) return;
}
}
}
class TDemo
{
public static void main(String args[]) throws Exception
{
//create an object to myclass
Myclass obj = new Myclass();
//create a thread and attach thread to that object
Thread t = new Thread(obj);
//Run the thread
t.start();
System.in.read();
obj.stop=true;
}
}

 how can you stop the thread
Stop method is deprecated
1)      create a Boolean variable and store false in that variable
 boolean stop = false;
2)      Make this variable true when the thread should be stopped
//stop the thread when enter pressed
System.in.read();
Obj.sop = true;
3)      if the variable is true return from the run() method
if(stop) return;









కామెంట్‌లు లేవు:

కామెంట్‌ను పోస్ట్ చేయండి