Default Constructor

Here is where the constructor is used in the main() method:

HelloObject anObject = new HelloObject();     // 2.  a HelloObject 
                                              //     is created.

But here is the class definition of HelloObject:

class HelloObject                                  
{                                                  
  void speak()                                     
  { 
    System.out.println("Hello from an object!");
  }
}

There is no constructor described in the class definition. This is OK. A class will have a constructor even if one is not explicitly included in the class definition. If the class definition does not include a constructor a default constructor is automatically supplied by the Java compiler.

The class definition of HelloObject does not include a constructor. But the compiler does something like this:

class HelloObject                                  
{
  HelloObject()  // default constructor
  {
  }
                                                 
  void speak()                                     
  { 
    System.out.println("Hello from an object!");
  }
}