question: void add ( Thread t ) { synchronized ( this ) { if ( destroyed ) { throw new IllegalThreadStateException ( ) ; } if ( threads == null ) { threads = new Thread [ 4 ] ; } else if ( nthreads == threads . length ) { threads = Arrays . copyOf ( threads , nthreads * 2 ) ; } threads [ nthreads ] = t ; nthreads ++ ; nUnstartedThreads -- ; } }
target:  Adds the specified thread to this thread group. <p> Note: This method is called from both library code and the Virtual Machine. It is called from VM to add certain system threads to the system thread group.