Constructor in java is a special type of method that is used to initialize the object.
Java constructor is invoked at the time of object creation. It constructs the values i.e. provides data for the object that is why it is known as constructor.
Rules for creating java constructor
- Constructor name must be same as its class name
- Constructor must have no explicit return type
- Default constructor (no-arg constructor)
- Parameterized constructor
Java Default Constructor
A constructor that have no parameter is known as default constructor. |
<class_name>(){}
Example of default constructor
In this example, we are creating the no-arg constructor in the Bike class. It will be invoked at the time of object creation. class Bike1{ Bike1(){System.out.println("Bike is created");} public static void main(String args[]){ Bike1 b=new Bike1(); } } Java parameterized constructor
Why use parameterized constructor
Parameterized constructor is used to provide different values to the distinct objects.
Example of parameterized constructor
void display(){System.out.println(id+" "+name);} public static void main(String args[]){ Student4 s1 = new Student4(111,"Karan"); Student4 s2 = new Student4(222,"Aryan");
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}
}
There are two types of constructors:
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