This document discusses multithreading in Java. It defines threads as pieces of code that run concurrently with other threads. It describes the life cycle of a thread as starting, running, and stopping. It also discusses how to create multithreaded programs in Java by either extending the Thread class or implementing the Runnable interface.

1. Java
Multithreading in Java
By Nishant S Mevawala

2. What are Threads?
• A piece of code that run in concurrent with other
threads.
• Each thread is a statically ordered sequence of
instructions.
• Threads are being extensively used express
concurrency on both single and multiprocessors
machines.
• Programming a task having multiple threads of
control – Multithreading or Multithreaded
Programming.
2

3. Life Cycle of
Thread

4. Threads
• Java has built in thread support for
Multithreading
• Synchronization
• Thread Scheduling
• Inter-Thread Communication:
currentThread
yield
sleep
start
run
stop
setPriority
getPriority
suspend
resume
• Java Garbage Collector is a low-priority thread

5. Types of Priority
1. Thread.MIN_PRIORITY - 1
2. Thread.MAX_PRIORITY - 10
3. Thread.NORM_PRIORITY - 5

6. Born
Stop
Start
Run
Running
Yield
Sleep
Suspended
Wait
Runnable
Stop
Resume
Wait
Notify
Stop
Dead

7. Ways of Multithreading in Java
•
•
Create a class that extends the Thread class
Create a class that implements the Runnable interface
• 1st Method: Extending the Thread class
class MyThread extends Thread
{
public void run()
{
// thread body of execution
•
•
}
}
Creating thread:
MyThread thr1 = new MyThread();
Start Execution:
thr1.start();

8. Extends Method example
class A extends Thread
{
public void run()
{
for(int i=1;i<=5;i++)
{
System.out.println("t From Thread A: i= "+i);
}
System.out.println("Exit from A");
}
}
class B extends Thread
{
public void run()
{
for(int j=1;j<=5;j++)
{
System.out.println("t From Thread B: j= "+j);
}
System.out.println("Exit from B");
}
}

9. class C extends Thread
{
public void run()
{
for(int k=1;k<=5;k++)
{
System.out.println("t From Thread C: k= "+k);
}
System.out.println("Exit from C");
}
}
class ThreadTest
{
public static void main(String S[])
{
new A().start();
new B().start();
new C().start();
}
}

10. 2nd method: Threads by implementing Runnable
interface
class ClassName implements Runnable
{
.....
public void run()
{
// thread body of execution
}
}
• Creating Object:
ClassName myObject = new ClassName();
• Creating Thread Object:
Thread thr1 = new Thread( myObject );
• Start Execution:
thr1.start();

11. Runnable method Example
class ththead implements Runnable
{
String nm;
Thread t;
public ththead(String st)
{
nm=st;
t=new Thread(this);
}
public void run()
{
for(int i=1;i<=5;i++)
{
System.out.println(nm + ":" +i);
}
}
}

12. class theadrun
{
public static void main(String args[])
{
ththead f1=new ththead("one");
ththead f2=new ththead("Two");
ththead f3=new ththead("Three");
f1.t.start();
f2.t.start();
f3.t.start();
}
}