constructor explain with example in java

Example 1: type of constructor in java

There are three types of constructors: 
Default, No-arg constructor and Parameterized.
  
If you do not implement any constructor in your class,
Java compiler inserts a default constructor into your code on your behalf.
This constructor is known as default constructor.
  
Constructor with no arguments is known as no-arg constructor

Constructor with arguments(or you can say parameters) is known as 
Parameterized constructor.

Example 2: constructor in java

public class ConstructorDemo
{
   int a;
   ConstructorDemo()
   {
      a = 26;
   }
   public static void main(String[] args)
   {
      ConstructorDemo obj = new ConstructorDemo();
      System.out.println(obj.a);
   }
}