Some Notes on Constructors/Constructors

• Default Constructor (Constructor): No parameter list. What it does is create a "default object". If you do not actively write a constructor, the compiler will automatically create a default no-argument constructor for you. The constructor is required, without it, there is no method to call and no object can be created.
• The name of the constructor is the same as that of the class, no modification, and no return value.
• Constructors can be overloaded. as follows:

   1 class Bird{
   2     Bird(int i){}
   3     Bird(double d){}
   4 }
   5 
   6 public class NoSynthesis {
   7     public static void main(String[] args) {
   8     Bird b1=new Bird2(1);
   9     Bird b2=new Bird2(1.0);
  10 //    Bird b3=new Bird();             Wrong!!!!!!!
  11     }
  12 }

  The original constructor Bird() of the class Bird has been overloaded twice, with different parameters each time, but the original no-parameter default constructor no longer exists. So new Bird() is a wrong way of writing, either taking an int parameter or a double parameter.