Java Questions

Executing more than one program simultaniously.(i.e at time)

Ex:

Windows media player  is a program

Internet explorer(IE) is another program executing both the programs  at a time is called multi tasking.

Inheritance is the ability to create new classes based on existing classes. It is useful to reuse existing code.

When an object is passed by value, this means that a copy of the object is passed. Thus, even if changes are made to that object, it doesn’t affect the original value. 

When an object is passed by reference, this means that the actual object is not passed, rather a reference of the object is passed. Thus, any changes made by the external method, are also reflected in all places.

main() method is called by the JVM even before the instantiation of the class, hence it is declared as static.

Client code must use setters and getters to access internal data in DataHiding

When ever two or more threads are sharing same data for updating then unpredicted result will be there in the data.

For Example take a thread is depositing amount in Account Object and another thread is withdrawing amount from the same Account Object.

when ever both threads are executed simultaneously then unexpected result is stored in the balance of the  Account Object.