2.9. Special Methods
At the level of the Java Virtual Machine, every constructor written in the Java programming language (JLS §8.8) appears as an instance initialization method that has the special name
<init>. This name is supplied by a compiler. Because the name
<init> is not a valid identifier, it cannot be used directly in a program written in the Java programming language. Instance initialization methods may be invoked only within the Java Virtual Machine by the invokespecial instruction (§invokespecial), and they may be invoked only on uninitialized class instances. An instance initialization method takes on the access permissions (JLS §6.6) of the constructor from which it was derived.
A class or interface has at most one class or interface ...