Tips n tricks for Threads

• Multithreading means multiple lines of a single program can be executed at the same time. The operating system is treating the programs as two separate and distinct processes. 
• Two ways of creating threads are : implementing an interface and extending a class. 
• The run() method is where all the work of theCounter class thread is done. 
• Only classes that implement the Runnable interface (and so are of type Runnable) can be targets of threads.
• The call to start() will call the target's run() method. The call to start() will return right away and the thread will start executing at the same time.
• Once a thread is stopped, it cannot be restarted with the start()command, since stop() will terminate the execution of a thread. Instead you can pause the execution of a thread with the sleep()method or temporarily cease the execution using suspend() method and resume() it at later point.
• Scheduling threads example. 
• Which exception might wait() throw? "InterruptedException" or "IllegalMonitorException". 
• Read about thread in detail here.
• Typical Producer Consumer example:

class Shared {
int num=0;

boolean value = false;

synchronized int get() {

  if (value==false)

  try {

    wait();

    }

  catch (InterruptedException e) {

     System.out.println("InterruptedException caught");

  }

System.out.println("consume: " + num);

value=false;

notify();

return num;

}

synchronized void put(int num) {

if (value==true)

  try {

    wait();

  }

  catch (InterruptedException e) {

      System.out.println("InterruptedException caught");

  }

    this.num=num;

    System.out.println("Produce: " + num);

    value=false;

    notify();

    }

    }

class Producer extends Thread {

  Shared s;

  Producer(Shared s) {

    this.s=s;

    this.start();

  }

  public void run() {

    int i=0;

    s.put(++i);

    }

}

class Consumer extends Thread{

  Shared s;

  Consumer(Shared s) {

    this.s=s;

    this.start();

  }
  public void run() {

    s.get();

    }}

public class InterThread{

  public static void main(String[] args) 

  {

    Shared s=new Shared();

    new Producer(s);

    new Consumer(s);

  }

}