Java Collection Unique hasUniqueObject(Collection collection)

Description

CollectionUtils Determine whether the given Collection only contains a single unique object.

License

Apache License

Parameter

Parameter	Description
collection	the Collection to check

Return

true if the collection contains a single reference or multiple references to the same instance, false else

Declaration

@SuppressWarnings("rawtypes")
public static boolean hasUniqueObject(Collection collection)

Method Source Code

//package com.java2s;
/*//from   w  w  w.ja v a2s  . c  o  m
 * @(#)SpringUtils.java
 * Create by Zollty_Tsow on 2013-11-30 
 * you may find ZollTy at csdn, github, oschina, stackoverflow...
 * e.g. https://github.com/zollty  http://www.cnblogs.com/zollty 
 * 
 * Copyright 2012-2013 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *      http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * 
 */

import java.util.Collection;

public class Main {
    /** CollectionUtils
     * 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 (collection == null || collection.isEmpty()) {
            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;
    }

    /**
     * Determine whether the given array is empty:
     * i.e. {@code null} or of zero length.
     * @param array the array to check
     */
    public static boolean isEmpty(Object[] array) {
        return (array == null || array.length == 0);
    }
}