enforce a method to be called java -

i have set of classes a1 an of such form :

public class a1{      //constructor method     public a1(...){...}     //init method     public void init(){...}     //some class specific method     ... } 

i ensure method init called after class initialization (possibly compiler error or sort of warning if not used) .

something like:

a1 a1=new a1(...); //some other code may relate a1 (e.g. changing default global values) a1.init(); // <-- if not used bad things happens. 

the limitation is:

that cannot use init() method within constructor

so there way of doing it? (except calling init() in constructor of course).

create boolean in class false, set true in init() , avoid call method if not true.

public class a1{      boolean initialized = false;      //constructor method     public a1(...){...}      //init method     public void init()     {         // init stuff         initialized = true;     }      //some class specific method     public void mymethod() {          if(!initialized) {             // print error         } else {             // stuff         }     }     ... }