Returns true if the given java.util.Collections contain exactly the same elements with exactly the same cardinalities. - Android java.util

Android examples for java.util:Collection Contains

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Description

Returns true if the given java.util.Collections contain exactly the same elements with exactly the same cardinalities.

Demo Code

/*/*from   w  w  w  . j  a  va  2s .  c o  m*/
 * (C) Copyright Itude Mobile B.V., The Netherlands
 * 
 * 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.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
//package com.java2s;
import java.util.Collection;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class Main {
    private static Integer INTEGER_ONE = new Integer(1);

    /**
     * Returns true if the given <i>java.util.Collections</i> contain exactly the same elements with exactly the same cardinalities.
     * That is, if the cardinality of e in a is equal to the cardinality of e in b, for each element e in a or b. 
     * 
     * @param a the first collection, must not be null
     * @param b the second collection, must not be null
     * @return if the collections contain the same elements with the same cardinalities.
     */
    public static boolean isEqualCollection(final Collection<?> a,
            final Collection<?> b) {

        if (a.size() != b.size()) {
            return false;

        } else {
            Map<?, ?> mapA = getCardinalityMap(a);
            Map<?, ?> mapB = getCardinalityMap(b);

            if (mapA.size() != mapB.size()) {
                return false;
            } else {
                Iterator<?> it = mapA.keySet().iterator();

                while (it.hasNext()) {
                    Object obj = it.next();
                    if (getFreq(obj, mapA) != getFreq(obj, mapB)) {
                        return false;
                    }
                }
                return true;
            }
        }
    }

    @SuppressWarnings("unchecked")
    public static Map<?, ?> getCardinalityMap(final Collection<?> coll) {
        Map count = new HashMap();

        for (Iterator<?> it = coll.iterator(); it.hasNext();) {
            Object obj = it.next();
            Integer c = (Integer) (count.get(obj));

            if (c == null) {
                count.put(obj, INTEGER_ONE);
            } else {
                count.put(obj, new Integer(c.intValue() + 1));
            }
        }
        return count;
    }

    private static final int getFreq(final Object obj,
            final Map<?, ?> freqMap) {
        Integer count = (Integer) freqMap.get(obj);
        return count != null ? count.intValue() : 0;
    }

    public static <T> T get(Iterable<T> collection, int idx) {
        Iterator<T> it = collection.iterator();
        T next = null;
        do {
            if (it.hasNext())
                next = it.next();
            else
                return null;
            idx--;
        } while (idx >= 0);
        return next;
    }
}

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