03-03-2025
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Q)What is synchronization?

=>Whenever multiple threads are trying to act upon a shared resource, there is
a chance of data inconsistency.To prevent such inconsistency, synchronization
is used.

=>To make a multithreaded application thread-safe, we use synchronization.

=>The mechanism of allowing only one thread at a time whenever multiple
threads are trying to act upon a shared resource is known as synchronization.

=>"synchornized" keyword is used to implement synchronization.

=>We have 2 types of synchronization
1)method level synchronization
2)block level synchronization(synchronized statement)

=>If we apply synchronized modifier to the method of an object, it is known as
method level synchronization.
For eg.
synchronized void withdraw(){
......
}

=>Instead of declaring the method as synchronized, we can create a block of
statements as synchronized. It is known as block level synchronization or
synchronized statement.

synchronized(object){
//code
}

Example 1:-
public void run(){
     synchronized(account){
          account.withdraw();
     }
}


Example 2:- public void withdraw(){
//code that doesn’t cause data inconsistency
synchronized(this) {
    //code that casuses data inconsistency
}

=>when synchronization is applied, the object is locked when a thread
accesses the code on that object. Until the lock is released no other
thread can access the code on the object.

Q)Explain about thread priorities.
=>Thread priority is a number used by thread scheduler in allocating CPU
 cycles to a particular thread in preference to other active threads.

 =>Thread priority ranges between 1 and 10.

 =>1 is the least priority, 10 is the maximum priority and 5 is the normal priority.
 =>java.lang.Thread class has 3 constants 

              1.)MIN_PRIORITY  (1)
	      2.)NORM_PRIORITY (5)
	      3.)MAX_PRIORITY(10)
=>We can set priority to a Thread by calling setPriority() method on the thread
object.
   For eg.   t1.setPriority(Thread.MAX_PRIORITY);
                                  OR
                t1.setPriority(10);
=>The higher the priority the more the CPU cycles to a thread.

=>By calling getPriority() method on the thread, we can find  its priority.

=>Priority setting will be effective if and only if it is done before it is activated.

=>By default, a thread has a priority of 5.

=>main thread has the priority of 5 and therefore all threads created in it
aslo have a priority of 5.

Q)What is inter-thread communication?
  =>One thread communicating with another thread by using
  wait(),notify() and notifyAll() methods is nothing but inter-thread communication.

  For eg.  In Producer-Consumer problem, interthread-communication
  is implemented. In a synchronized environment only, these 3 methods should
  be called.

Q)Is Java purely object oriented?
=>No.
=>The moment we have primitive data types in a Programming language,
it can't be called as purely object oriented.

Note:- Java projects are 100% object oriented.

Q)What are wrapper classes?
=>In java.lang package, for every primitive data type, one corresponding Java
class is given.These classes are known as wrapper classes.
 
primitive type          wrapper
************************************
int                          Integer
long                        Long
byte                       Byte
short                      Short
float                       Float
double                    Double
boolean                  Boolean
char                       Character

Note:- An instance of a wrapper class wraps(encapsulates) primitive value in it
and hence the name.