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Constructor

Constructor in Java

A constructor in Java is a block of code similar to a method that’s called when an instance of an object is created.
A constructor doesn’t have a return type.
The name of the constructor must be the same as the name of the class.
A constructor is called automatically when a new instance of an object is created.

Types of java constructors:


There are two types of constructors in java:
1. Default constructor (no-arg constructor)
2. Parameterized constructor

1)Default Constructor:

A constructor having no parameter is known as default constructor and no-arg constructor.

public class DC {
public DC(){
System.out.println(” default constructor…”);
}
public static void main(String a[]){
DC mdc = new DC();
}}

 

2)parameterized constructor:


A constructor having an argument list is known as a parameterized constructor.
Parameterized constructors are used to supply dissimilar values to the distinct objects.

 

public class PC{
PC(int a, int b){
System.out.println(“Parameterized Constructor having 2 parameters”);
System.out.println(a+b);

}
PC(int a, int b, int c){
System.out.println(“Parameterized Constructor having Three parameters”);
System.out.println(a+b+c);
}
public static void main(String args[]){
PC pc1 = new PC(12, 12);
PC pc2 = new PC(1, 2, 13);
}}

 

Constructor Overloading:


Constructor overloading is a concept of having more than one constructor with different parameters list, in such a way so that each constructor performs a different task.

 

 

public class Employee{
int id;
String name;
int age;
Employee(int i,String n){
id = i;
name = n;
}
Employee(int i,String n,int a){
id = i;
name = n;
age=a;
}
void display()
{

System.out.println(id+” “+name+” “+age);
}
public static void main(String args[]){
Employee s1 = new Employee(256,”James”);
Employee s2 = new Employee(257,”Gosling”,25);
s1.display();
s2.display();
}
}