super() in constructor

super() refers to the extended class (not an implemented interface). Which in this case is Object

So it will call the constructor in Object (Which does nothing)

super calls the constructor of the extended class. All classes in Java derive from Object. Additionally, if the author of a class doesn't create a constructor for the class, a default constructor is created that does nothing.

In your case, super is calling the default constructor of Object.

If you'd like to learn more about Object, you can read the source code of Object.java here.

Super is referencing to the extended class. By default it is the Object class. The constructor in Object does nothing. In other words you can delete this line as it is not necessary.

Please also note what Oracle is saying about this topic:

If a constructor does not explicitly invoke a superclass constructor, the Java compiler automatically inserts a call to the no-argument constructor of the superclass. If the super class does not have a no-argument constructor, you will get a compile-time error. Object does have such a constructor, so if Object is the only superclass, there is no problem.

Source: http://docs.oracle.com/javase/tutorial/java/IandI/super.html