Syncronized methods are executed only after a lock is 
acheived on the classes or objects specified in the methids 
and after that the methids are executed

Synchronized methods are executed after lock is acieved on 
class or object specified in the synchronized statement

1. Extending the Thread class
2. Implementing Runnable interface in a class and then
passing its reference to a new Thread.
3. Creating an anonymous class to extend the Thread class.
4. Creating an anonymous class to implement the Runnable
interface and then passing its reference to a new Thread.

There are two different ways to create a Thread.  One is 
extends Thread class and implement Runnable Interface.  
Better to go for Runnable interface.  It will have a method 
run().  You should override in the sub class.  Even, you 
can extend another class to the same thread class.

No, each thread will have its own copy of the variable.

The reason is that run() is a method and any variable
declared inside a method is considered a local method and
its scope remains only within that method. If new thread
instances are spawned then each thread instances' run()
method will have their own copy of the variable.

Semaphore variable are to make sure that some shared 
variable is not being modified/updated simultaneously by 
two separate processes/threads.

It is being used to prevent DEADLOCK upto some extent only.
It is a primitive level mechanism.

Semaphore is to solve the problem of syncronisation. It is 
a monitor, to monitor the critical section of the program.

it can be implemented with the help of the a single 
variable and depending upon the value of that variable 
thread is allowed to enter in the critical section.

JMS is based on Java technology it used for messaging 
between different applications.JMS provides asynchronous 
messaging.

no synchronised is not a modifier

it is a key word which can do a specific functionality on 
thread.