Main.java Source code

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Here is the source code for Main.java

Source

//package com.java2s;
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

import java.util.Collection;

import java.util.HashSet;
import java.util.Iterator;

import java.util.Set;

public class Main {
    /**
     * Returns <code>true</code> iff all elements of {@code coll2} are also contained
     * in {@code coll1}. The cardinality of values in {@code coll2} is not taken into account,
     * which is the same behavior as {@link Collection#containsAll(Collection)}.
     * <p>
     * In other words, this method returns <code>true</code> iff the
     * {@link #intersection} of <i>coll1</i> and <i>coll2</i> has the same cardinality as
     * the set of unique values from {@code coll2}. In case {@code coll2} is empty, {@code true}
     * will be returned.
     * <p>
     * This method is intended as a replacement for {@link Collection#containsAll(Collection)}
     * with a guaranteed runtime complexity of {@code O(n + m)}. Depending on the type of
     * {@link Collection} provided, this method will be much faster than calling
     * {@link Collection#containsAll(Collection)} instead, though this will come at the
     * cost of an additional space complexity O(n).
     *
     * @param coll1  the first collection, must not be null
     * @param coll2  the second collection, must not be null
     * @return <code>true</code> iff the intersection of the collections has the same cardinality
     *   as the set of unique elements from the second collection
     * @since 4.0
     */
    public static boolean containsAll(final Collection<?> coll1, final Collection<?> coll2) {
        if (coll2.isEmpty()) {
            return true;
        } else {
            final Iterator<?> it = coll1.iterator();
            final Set<Object> elementsAlreadySeen = new HashSet<Object>();
            for (final Object nextElement : coll2) {
                if (elementsAlreadySeen.contains(nextElement)) {
                    continue;
                }

                boolean foundCurrentElement = false;
                while (it.hasNext()) {
                    final Object p = it.next();
                    elementsAlreadySeen.add(p);
                    if (nextElement == null ? p == null : nextElement.equals(p)) {
                        foundCurrentElement = true;
                        break;
                    }
                }

                if (foundCurrentElement) {
                    continue;
                } else {
                    return false;
                }
            }
            return true;
        }
    }

    /**
     * Null-safe check if the specified collection is empty.
     * <p>
     * Null returns true.
     *
     * @param coll  the collection to check, may be null
     * @return true if empty or null
     * @since 3.2
     */
    public static boolean isEmpty(final Collection<?> coll) {
        return coll == null || coll.isEmpty();
    }
}