OOPS Interview Questions in Java for Freshers

OOPS Interview Questions in Java for Freshers. An advanced Object Oriented Programming Systems(Oops) Concepts in Java for good program in java programming language. The fundamentals of OOPs will be covered. Inheritance, data binding, polymorphism, and other notions are all part of the Object-Oriented Programming paradigm. 

The object-oriented programming language Simula is regarded as the first. A genuinely object-oriented programming language is a programming paradigm in which everything is represented as an object. Object-oriented programming’s primary goal is to construct real-world things such as objects, classes, abstraction, inheritance, and polymorphism.

Oops in Java Programming Concepts

A real-world entity such as a pen, chair, table, computer, watch, and so on is referred to as an object. Object-Oriented Programming (OOP) is a programming methodology or paradigm that uses classes and objects to create a program. It provides various notions that simplify software creation and maintenance.












What is Object in Java Oops Concepts

Any entity with state and behaviour is referred to as an object. An Object can be used to represent a class instance. An object is a piece of data that has an address and takes up memory. Even if they are unaware of each other’s data or code, objects can communicate. The type of message that is accepted and the type of response that the objects provide are the only things that matter.

Characteristics of Objects in Oops

The data of an object represents its current state. The behaviour of an object is represented by its behaviour, which includes depositing, withdrawing, and so on. An object’s identity is typically represented by a unique ID. The ID’s value is hidden from the outside world. The JVM, on the other hand, employs it to uniquely identify each object internally.

public class Main
int a = 100;

public static void main(String[] args)
Main myObj1 = new Main();
Main myObj2 = new Main();





What is Class in Java Oops Concepts

The term “class” refers to a group of items. It’s a logical thing. A class can alternatively be thought of as a blueprint from which an individual object can be created. Class doesn’t take up any room. In Java, a class is a template that is used to build objects and define their data types and actions. Classes are groups of things, and objects are the things that make up each group. The essential class properties should be present in all class objects.

What is Inheritence in Java Oops Concepts

Inheritance is a feature in Java that transfers properties from one class to another, such as the relationship between father and son. A class in Java can take on the characteristics and methods of another class. The sub-class, often known as the child class, is the class that inherits the properties. Inheritance occurs when one object inherits all of the characteristics and actions of a parent object. It allows for code reuse. It’s utilized to achieve polymorphism at runtime.

What is Polymorphism in Java Oops Concepts

In Java, polymorphism refers to an object’s ability to take several forms. Simply put, polymorphism in Java allows us to do the same task in multiple ways. Polymorphism is a feature of Java’s object-oriented programming language that allows for the completion of a single task in different ways.

What is Abstraction in Java Oops Concepts

Abstract is a non-access modifier in Java that can be used on classes, methods, and variables, but not variables. It’s used to achieve abstraction, which is one of the major foundations of Object Oriented Programming. Abstraction is the process of concealing internal features while displaying functionality. We don’t know the internal processes of a phone call, for example. To achieve abstraction in Java, we employ abstract classes and interfaces.

What is Encapsulation in Java Oops Concepts

Encapsulation is the process of combining code and data into a single unit. A capsule, for example, is coated in various drugs. Encapsulation is demonstrated using a Java class. Because all data members are private in a Java bean, it is a fully enclosed class. In Java, encapsulation is a way for encapsulating data and the code that acts on it as a single unit. Encapsulation means that a class’s variables are concealed from other classes and can only be accessible through its current class’s methods.

What is Coupling in Java Oops Concepts

Another class’s knowledge, information, or reliance is referred to as coupling. When classes are aware of one another, this problem arises. Strong coupling occurs when one class has access to the details of another class. To show the visibility level of a class, method, or field in Java, we use the private, protected, and public modifiers. Because no concrete implementation exists, interfaces can be used for the weaker coupling.

What is Cohesion in Java Oops Concepts

The level of cohesion of a component that performs a single well-defined task is referred to as cohesion. Cohesion is the most closely associated Object Oriented principle with ensuring that a class is designed with a single, well-focused purpose. A highly cohesive method is used to complete a single well-defined task. The task will be divided into separate parts using the weakly cohesive method. Because it contains I/O-related classes and interfaces, the java.io package is very cohesive. The java.util package, on the other hand, is a disjointed collection of classes and interfaces.

What is Association in Java Oops Concepts

The relationship between the objects is represented by association. One object can be linked to one or more objects in this case. In Java, an association is a link or relationship between two different classes that is established through their objects. The association relationship describes how objects are connected and how they use each other’s features.





What is Aggregation in Java Oops Concepts

Aggregation is a method of attaining Association. Aggregation refers to a relationship in which one object’s state includes other objects. It symbolizes a shaky connection between objects. In Java, it’s known as a has-a relationship. The is-a relationship, for example, is represented by inheritance. It’s yet another way to recycle items.

What is Composition in Java Oops Concepts

The composition is also a way to achieve Association. The composition represents the relationship where one object contains other objects as a part of its state. There is a strong relationship between the containing object and the dependent object. It is the state where containing objects do not have an independent existence. If you delete the parent object, all the child objects will be deleted automatically.