Use of Constructor in Java | Purpose of Constructor in Java

When an object is instantiated in Java, a particular kind of method called a constructor is called. Initialising an object's state is the aim of a constructor. Setting the object's initial settings for its properties and carrying out any other setup necessary to ensure proper operation are included in this initialization process.

Purpose and Uses of Constructors

1. Initialization of Object State

One of the primary objectives of constructors is to initialise the state of an object. A constructor is invoked when an object is created with the new keyword in order to guarantee that the object has a defined state from the start. It includes carrying out any necessary setup or initialising the object's attribute values.

In this example, when a new Student object is generated, the parameterized constructor of the Student class initialises the name and age attributes.

2. Providing Default Values

Constructors-particularly default constructors-assist in offering default settings for the attributes of the object. The default constructor makes sure that the properties are set to default values in the event that no values are explicitly supplied during the object construction process.

3. Object Creation and Memory Allocation

Memory is set aside for an object created using the new keyword, and its initial state is set by calling the constructor.

Here, the constructor Student(String name, int age) is invoked during the creation of the newStudent object.

4. Constructor Overloading

Java allows you to have multiple constructors within a class, each with a different set of parameters. It is known as constructor overloading. It provides flexibility in creating objects with varying initializations.

Let's create an example to demonstrate the use of constructors in Java:

Car.java

Output:

Make: Toyota
Model: Camry
Year: 2022

Conclusion

Constructors are essential because they allow constructor overloading for more flexibility and default values, facilitate object creation and memory allocation, and initialize the state of objects. Constructors make a big difference in the usefulness and integrity of your code, whether they are parameterized to allow for customized initializations or default to offer standard values. Any Java programmer must comprehend constructors and know how to use them properly. It enhances the general layout and organisation of your software in addition to guaranteeing correct object initialization.