How is it possible ? What exactly is happening behind in the code?

Question

String str4 = new Interger().toString();
/*As strings are non-primitive types the actual way of creating an object is
Classname Variablename = new Classname();
String str4 = new String();
But the above case is totally different.
I want to know whether even though a string is object related it has some specific way to create an object Or usually there are more ways to create an object than the conventional way of (Classname varname = new Classname(); */