Java Threads
- A thread is a process that runs independently.
- A program starts off running using a single thread which spawns other threads.
- Multi-threading is a major part of Java Network Programming.
- To start the execution of a thread, the start( ) method is called.
- In turn, the start( ) method calls the run( ) method.
- You may stop or interrupt a thread by calling the stop( ) or interrupt( )
method, respectively.
- There are two types of threads: a daemon thread and a user thread.
- A daemon thread is a background thread that is subordinate to the thread that
created it. It is created by calling the setDaemon( ) method with an argument set
to true before it starts.
- A user thread has a life of its own.
- There are two ways of defining a multi-threaded application: instantiate a thread
or implement a Runnable interface.
// A Thread subclass application
public class SampleThread extends Thread {
private int threadNum;
public SampleThread(int val){
threadNum = val;
}//end of constructor
public void run( ){
System.out.println("Starting Thread Number: " + threadNum);
try {
Thread.sleep((long)(Math.random()*10000));
}catch (InterruptedException e) { }
System.out.println("Stopping Thread Number: " + threadNum);
}//end of run
public static void main (String [ ] args){
for (int i=0; i<5; i++){
Thread thr = new SampleThread(i);
thr.start();
}
}//end of main
}//end of class definition
- Sometimes, it is better to create a thread by implementing a Runnable because we
may need to extend the functionality of the instance object. Note that, in Java,
inheritance is allowed only once.
