Creating Object in a thread safety way

Question

Directly from this web site, I came across the following description about creating object thread safety.

Warning: When constructing an object that will b

Answer 1

Its describing the following situation:

Thread1:
 //we add a reference to this thread
 object.add(thread1Id,this);
 //we start to initialize this thread, but suppose before reaching the next line we switch threads
 this.initialize(); 
Thread2:     
//we are able to get th1, but its not initialized properly so its in an invalid state 
//and hence th1 is not valid
Object th1 = object.get(thread1Id);