whats a default constructor code example

Example 1: default constructor

public class Vehicle {
  protected String vin;
  protected int modelYear;
  
  public Vehicle() { } 
  
  public Vehicle(String vin) { 
    this.vin = vin;
  }
   
  public Vehicle(String vin, int modelYear) { 
    this.vin = vin;
    this.modelYear = modelYear;
  }
}

Example 2: default constructor java

class NoteBook{
   /*This is default constructor. A constructor does
    * not have a return type and it's name
    * should exactly match with class name
    */
   NoteBook(){
      System.out.println("Default constructor");
   }
   public void mymethod()
   {
      System.out.println("Void method of the class");
   }
   public static void main(String args[]){
	/* new keyword creates the object of the class
         * and invokes constructor to initialize object
         */
	NoteBook obj = new NoteBook();
	obj.mymethod();
   }
}