Returns true iff the given Collection s contain exactly the same elements with exactly the same cardinality. - Android java.util

Android examples for java.util:Collection Filter

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Description

Returns true iff the given Collection s contain exactly the same elements with exactly the same cardinality.

Demo Code

/*// w w  w  . j  a v  a2 s .  c  om
 * Copyright 1999-2004 The Apache Software Foundation
 *
 * 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;
import java.util.NoSuchElementException;

public class Main {
    /**
     * Returns <tt>true</tt> iff the given {@link Collection}s contain
     * exactly the same elements with exactly the same cardinality.
     * <p>
     * That is, iff the cardinality of <i>e</i> in <i>a</i> is
     * equal to the cardinality of <i>e</i> in <i>b</i>,
     * for each element <i>e</i> in <i>a</i> or <i>b</i>.
     */
    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;
            }
        }
    }

    /**
     * Returns a {@link Map} mapping each unique element in
     * the given {@link Collection} to an {@link Integer}
     * representing the number of occurances of that element
     * in the {@link Collection}.
     * An entry that maps to <tt>null</tt> indicates that the
     * element does not appear in the given {@link Collection}.
     */
    public static Map getCardinalityMap(final Collection col) {
        HashMap count = new HashMap();
        Iterator it = col.iterator();
        while (it.hasNext()) {
            Object obj = it.next();
            Integer c = (Integer) (count.get(obj));
            if (null == c) {
                count.put(obj, new Integer(1));
            } else {
                count.put(obj, new Integer(c.intValue() + 1));
            }
        }
        return count;
    }

    private static final int getFreq(final Object obj, final Map freqMap) {
        try {
            return ((Integer) (freqMap.get(obj))).intValue();
        } catch (NullPointerException e) {
            // ignored
        } catch (NoSuchElementException e) {
            // ignored
        }
        return 0;
    }
}

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