Java tutorial
//package com.java2s; import java.util.Collection; import java.util.Map; public class Main { /** * Determine whether the given Collection only contains a single unique object. * @param collection the Collection to check * @return {@code true} if the collection contains a single reference or * multiple references to the same instance, {@code false} else */ @SuppressWarnings("rawtypes") public static boolean hasUniqueObject(Collection collection) { if (isEmpty(collection)) { return false; } boolean hasCandidate = false; Object candidate = null; for (Object elem : collection) { if (!hasCandidate) { hasCandidate = true; candidate = elem; } else if (candidate != elem) { return false; } } return true; } /** * Return {@code true} if the supplied Collection is {@code null} * or empty. Otherwise, return {@code false}. * @param collection the Collection to check * @return whether the given Collection is empty */ @SuppressWarnings("rawtypes") public static boolean isEmpty(Collection collection) { return (collection == null || collection.isEmpty()); } /** * Return {@code true} if the supplied Map is {@code null} * or empty. Otherwise, return {@code false}. * @param map the Map to check * @return whether the given Map is empty */ @SuppressWarnings("rawtypes") public static boolean isEmpty(Map map) { return (map == null || map.isEmpty()); } }