Question

Does JVM call default Constructor of Anonymous Class to create instance.

My understanding may be stupid for that. I think, even if Reflection API is used to create an instance, there will be at least Default Constructor. Anonymous Class have a Default Constructor? Otherwise, how JVM or whatever create instance?

Answer 1

Yes it does. You can even use other constructors through specifying parameters:

Given

public abstract class A {
   String str;
   public A(String str){
       this.str=str;
   }
   public abstract void doSomething();
}

You can do

...


A a = new A("Hello World") {
   public void doSomething() {
       System.out.println(str);
   }
};
a.doSomething();

When a class doesn’t have an explicit constructor, it has an implicit default empty constructor. That is called, just as any other constructor would be called.