public synchronized boolean addIfAbsent(E object) {if (contains(object)) {return false;}add(object);return true;}

public synchronized boolean addIfAbsent ( E object ) { if ( contains ( object ) ) { return false ; } add ( object ) ; return true ; }
public virtual bool addIfAbsent(E @object){lock (this){if (contains(@object)){return false;}add(@object);return true;}}
