Constructor in Java

In Java, a constructor is a special type of method that is invoked when an object is created. Its primary purpose is to initialize the newly created object. Constructors are called automatically when an object of a class is created, and they typically set initial values for the object’s attributes or perform other necessary setup tasks.

In the below PDF we discuss about String in Java  in detail in simple language, Hope this will help in better understanding.

Types of Constructors in java:

1. Default Constructor:

A default constructor is automatically provided by Java if no constructors are explicitly defined in a class.
It initializes the object’s instance variables to their default values (e.g., 0 for numeric types, null for reference types).

public class MyClass {
// Default constructor (implicitly provided by Java)

2. Parameterized Constructor:

A parameterized constructor accepts one or more parameters to initialize the object’s state.
It allows objects to be initialized with specific values during creation.

public class Car {
String brand;
int year;

// Parameterized constructor
public Car(String brand, int year) {
this.brand = brand;
this.year = year;

3. Copy Constructor:

A copy constructor creates a new object by copying the state of an existing object of the same class.
It is used to create a deep copy of an object, ensuring that changes to one object do not affect the other.

public class Student {
String name;
int age;

// Copy constructor
public Student(Student other) { =;
this.age = other.age;

The Role of Constructors:

Constructors play a vital role in Java programming for several reasons:

  • Object Initialization: Constructors initialize the state of objects, ensuring they are in a valid and usable state upon creation.
  • Setting Initial Values: They allow developers to set initial values for object attributes, providing a way to customize object creation.
  • Constructor Chaining: Constructors can call other constructors within the same class using the this() keyword, enabling code reusability and reducing redundancy.
  • Encapsulation: Constructors can be used to enforce encapsulation by initializing private variables and preventing direct access to them from outside the class.


Constructors are a fundamental aspect of object-oriented programming in Java. They provide a mechanism for initializing objects and ensuring their proper state before they are used in a program. By understanding the types and usage of constructors, developers can write more robust and maintainable code. Whether it’s initializing simple objects or managing complex data structures, constructors play a crucial role in shaping the behavior and functionality of Java programs.

Must Read: Array In Java

Related Question

A constructor in Java is a special type of method that is automatically invoked when an object of a class is created. It is used to initialize the object’s state.

The main purpose of a constructor is to initialize the newly created object. It sets initial values for the object’s attributes or performs any other setup necessary for the object to function correctly.

Constructors are distinguished from regular methods by their name, which must match the class name exactly, and by the fact that they do not have a return type, not even void. They are automatically called when an object is created, whereas regular methods are called explicitly by name.

Yes, a class can have multiple constructors. This is known as constructor overloading. Each constructor must have a unique signature, meaning they must have different parameter lists.

If a class does not explicitly define any constructors, Java provides a default constructor automatically. This default constructor takes no arguments and initializes any instance variables to their default values (e.g., numeric types to 0, references to null).



A Complete Guide to Java

Java Regex | Regular Expressions

Java Collection Framework The Java

Multithreading in Java Multithreading refers

File Handling in Java File

Exception Handling in Java An

Packages in Java A package

Leave a Comment

Your email address will not be published. Required fields are marked *

// Sticky ads