Java Questions

Pass By Reference means the passing the address itself rather than passing the value. Passby Value means passing a copy of the value to be passed.

Various elements of OOP are:

• Object

• Class

• Method

• Encapsulation

• Information Hiding

• Inheritance

• Polymorphism

yes if the method is ovreriding method

no if the method is not overriding method

Use Interfaces when…

- You see that something in your design will change frequently.

- If various implementations only share method signatures then it is better to use Interfaces.

- You need some classes to use some methods which you don't want to be included in the class, then you go for the interface, which makes it easy to just implement and make use of the methods defined in the interface.

Use Abstract Class when…

- If various implementations are of the same kind and use common behavior or status then abstract class is better to use.

- When you want to provide a generalized form of abstraction and leave the implementation task with the inheriting subclass.

- Abstract classes are an excellent way to create planned inheritance hierarchies. They're also a good choice for nonleaf classes in class hierarchies.

Path and Classpath are operating system level environment variales. Path is used define where the system can find the executables(.exe) files and classpath is used to specify the location .class files.

Yes, we can. In order to compile a java program, we don't require any main method. But to execute a java program we must have a main in it (unless it is an applet or servlet). Because main is the starting point of a java program.

A thread is a lightweight subprocess, a smallest unit of processing. It is a separate path of execution. It shares the memory area of process.

As shown in the above figure, thread is executed inside the process. There is context-switching between the threads. There can be multiple processes inside the OS and one process can have multiple threads.

Wrapped classes are classes that allow primitive types to be accessed as objects.