Finds the difference between two HashMaps a and b. - Java java.util

Java examples for java.util:Map Operation

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Description

Finds the difference between two HashMaps a and b.

Demo Code

/**//from   ww  w  .ja  v  a  2  s. c  o m
 *  Copyright 2009 Welocalize, Inc. 
 *  
 *  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.Iterator;

import java.util.HashMap;

public class Main {
    /**
     * Finds the difference between two HashMaps a and b.
     * Returns a HashMap containing elements in b that are not in a
     *
     * @return the difference as a HashMap
     */
    public static HashMap hashMapDifference(HashMap a, HashMap b) {
        Iterator bKeyIterator = b.keySet().iterator();
        Object key;
        Object value;
        HashMap difference = new HashMap();

        while (bKeyIterator.hasNext()) {
            key = bKeyIterator.next();
            if (!a.containsKey(key)) {
                value = b.get(key);
                difference.put(key, value);
            }
        }
        return difference;
    }

    /**
     * Returns the element at the specified position in the 
     * collection. 
     * Shifts any subsequent elements to the left 
     * (subtracts one from their indices). 
     * Returns the element that was removed from the Collection.
     * @param p_collection a Collection
     * @param p_index index of element to return.
     * @returns the element at the specified position in the 
     * collection.
     */
    public static Object get(Collection p_collection, int p_index) {
        if (p_collection == null) {
            return null;
        }
        Iterator it = p_collection.iterator();
        for (int i = 0; it.hasNext(); i++) {
            if (i == p_index) {
                return it.next();
            }
        }
        return null;
    }
}

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