java - Can't understand barrier code -

i ran across barrier code , cannot understand barrierpost method.

im supposed use code solve exercise 2 teams of threads race eachother count 10000.

i don't understand why same condition has different results opposite

public class barrier {      private int currentposters = 0, totalposters = 0;     private int passedwaiters = 0, totalwaiters = 1;      /**      * @param totalposters - nr of threads required start waiting threads      * @param totalwaiters - nr of threads started later       */      public barrier (int totalposters, int totalwaiters) {      this.totalposters = totalposters;       this.totalwaiters = totalwaiters;      }      public synchronized void init(int i) {         totalposters = i; currentposters=0;     }      public synchronized void barrierset(int i) {         totalposters = i; currentposters=0;     }       public synchronized void barrierwait() {         boolean interrupted = false;         while (currentposters = totalposters) {             try {wait();}              catch (interruptedexception ie) {interrupted=true;}         }         passedwaiters++;         if (passedwaiters == totalwaiters) {             currentposters = 0; passedwaiters = 0; notifyall();         }         if (interrupted) thread.currentthread().interrupt();     }      public synchronized void barrierpost() {         boolean interrupted = false;   // in case poster thread beats barrierwait, keep count of posters.         while (currentposters == totalposters) {              try {wait();}              catch (interruptedexception ie) {interrupted=true;}         }         currentposters++;         if (currentposters == totalposters) notifyall();         if (interrupted) thread.currentthread().interrupt();    } }  

can help?