geode-core/src/main/java/org/apache/geode/internal/SetUtils.java

/*
 * 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.
 */
package org.apache.geode.internal;

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

/**
 * Utility methods for managing and using Sets
 * 
 * @since GemFire 59poc
 * 
 */
public class SetUtils {
  public static <T> boolean intersectsWith(final Set<? extends T> a, final Set<? extends T> b) {
    if (a == b) {
      return true;
    }
    final Set/* <T> */ lSet, sSet;
    if (a.size() >= b.size()) {
      lSet = a;
      sSet = b;
    } else {
      lSet = b;
      sSet = a;
    }
    for (Iterator i = sSet.iterator(); i.hasNext();) {
      Object item = i.next();
      if (lSet.contains(item)) {
        return true;
      }
    }
    return false;
  }

  public static /* T */ Set/* <T> */ intersection(final Set/* <T> */ a, final Set/* <T> */ b) {
    if (a == b) {
      return a;
    }
    final Set/* <T> */ lSet, sSet;
    if (a.size() >= b.size()) {
      lSet = a;
      sSet = b;
    } else {
      lSet = b;
      sSet = a;
    }
    HashSet /* <T> */ ret = new HashSet/* <T> */();
    for (Iterator i = sSet.iterator(); i.hasNext();) {
      Object item = i.next();
      if (lSet.contains(item)) {
        ret.add(item);
      }
    }
    return ret;
  }
}