Method contains

lib/java/util/HashSet.java:133–136

Searches this HashSet for the specified object. @param object the object to search for. @return true if object is an element of this HashSet, false otherwise.

(Object object)

     *         {@code HashSet}, {@code false} otherwise.
     */
    @Override
    public boolean contains(Object object) {
        return backingMap.containsKey(object);
    }

    /**
     * Returns true if this {@code HashSet} has no elements, false otherwise.