CSITQuestions Free Education For Everyone

If a class contain any abstract method then the class is declared as abstract class. An abstract class is never instantiated. It is used to provide abstraction. Although it does not provide 100% abstraction because …

Object and Classes Since Java is an object oriented language, complete java language is build on classes and object. Java is also known as a strong Object oriented programming language(oops). OOPS is a programming approach …

Method describe behavior of an object. A method is a collection of statements that are group together to perform an operation. Syntax : return-type methodName(parameter-list) { //body of method } Example of a Method public …

Constructors in Java A constructor is a special method that is used to initialize an object.Every class has a constructor, if we don’t explicitly declare a constructor for any java class the compiler builds a …

this keyword this keyword is used to refer to current object. this is always a reference to the object on which method was invoked. this can be used to invoke current class constructor. this can …

In Java destruction of object from memory is done automatically by the JVM. When there is no reference to an object, then that object is assumed to be no longer needed and the memory occupied …

Modifiers are keywords that are added to change meaning of a definition. In Java, modifiers are catagorized into two types, Access control modifier Non Access Modifier 1) Access control modifier Java language has four access …

Inheritance (IS-A) Inheritance is one of the key features of Object Oriented Programming. Inheritance provided mechanism that allowed a class to inherit property of another class. When a Class extends another class it inherits all …

Aggregation (HAS-A) HAS-A relationship is based on usage, rather than inheritance. In other words, class A has-a relationship with class B, if code in class A has a reference to an instance of class B. …

Method Overriding When a method in a sub class has same name and type signature as a method in its super class, then the method is known as overridden method. Method overriding is also referred …

Dynamic method dispatch is a mechanism by which a call to an overridden method is resolved at runtime. This is how java implements runtime polymorphism. When an overridden method is called by a reference, java …

In Java, instanceof operator is used to check the type of an object at runtime. It is the means by which your program can obtain run-time type information about an object. instanceof operator is also …

The command line argument is the argument passed to a program at the time when you run it. To access the command-line argument inside a java program is quite easy, they are stored as string …

Package are used in Java, in-order to avoid name conflicts and to control access of class, interface and enumeration etc. A package can be defined as a group of similar types of classes, interface, enumeration …

If a class contain any abstract method then the class is declared as abstract class. An abstract class is never instantiated. It is used to provide abstraction. Although it does not provide 100% abstraction because …