content: /*
   * Copyright (C) 2007 The Android Open Source Project
   *
   * 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.google.android.collect;
  
  import android.annotation.UnsupportedAppUsage;
  import android.util.ArraySet;
  
  import java.util.Collections;
  import java.util.EnumSet;
  import java.util.HashSet;
  import java.util.SortedSet;
  import java.util.TreeSet;
  
  /**
   * Provides static methods for creating mutable {@code Set} instances easily and
   * other static methods for working with Sets.
   *
   */
  public class Sets {
      
      /**
       * Creates an empty {@code HashSet} instance.
       *
       * <p><b>Note:</b> if {@code E} is an {@link Enum} type, use {@link
       * EnumSet#noneOf} instead.
       *
       * <p><b>Note:</b> if you only need an <i>immutable</i> empty Set, 
       * use {@link Collections#emptySet} instead.
       *
       * @return a newly-created, initially-empty {@code HashSet}
       */
      @UnsupportedAppUsage
      public static <K> HashSet<K> newHashSet() {
          return new HashSet<K>();
      }
  
      /**
       * Creates a {@code HashSet} instance containing the given elements.
       *
       * <p><b>Note:</b> due to a bug in javac 1.5.0_06, we cannot support the
       * following:
       *
       * <p>{@code Set<Base> set = Sets.newHashSet(sub1, sub2);}
       *
       * <p>where {@code sub1} and {@code sub2} are references to subtypes of {@code
       * Base}, not of {@code Base} itself. To get around this, you must use:
       *
       * <p>{@code Set<Base> set = Sets.<Base>newHashSet(sub1, sub2);}
       *
       * @param elements the elements that the set should contain
       * @return a newly-created {@code HashSet} containing those elements (minus
       *     duplicates)
       */
      @UnsupportedAppUsage
      public static <E> HashSet<E> newHashSet(E... elements) {
          int capacity = elements.length * 4 / 3 + 1;
          HashSet<E> set = new HashSet<E>(capacity);
          Collections.addAll(set, elements);
          return set;
      }
  
      /**
       * Creates an empty {@code SortedSet} instance.
       *
       * @return a newly-created, initially-empty {@code SortedSet}.
       */
      @UnsupportedAppUsage
      public static <E> SortedSet<E> newSortedSet() {
          return new TreeSet<E>();
      }
  
      /**
       * Creates a {@code SortedSet} instance containing the given elements.
       *
       * @param elements the elements that the set should contain
       * @return a newly-created {@code SortedSet} containing those elements (minus
       *     duplicates)
       */
      public static <E> SortedSet<E> newSortedSet(E... elements) {
          SortedSet<E> set = new TreeSet<E>();
          Collections.addAll(set, elements);
          return set;
      }
  
      /**
       * Creates a {@code ArraySet} instance.
       */
      @UnsupportedAppUsage
      public static <E> ArraySet<E> newArraySet() {
          return new ArraySet<E>();
      }
  
      /**
       * Creates a {@code ArraySet} instance containing the given elements.
       */
      @UnsupportedAppUsage
      public static <E> ArraySet<E> newArraySet(E... elements) {
          int capacity = elements.length * 4 / 3 + 1;
          ArraySet<E> set = new ArraySet<E>(capacity);
          Collections.addAll(set, elements);
          return set;
      }
  }
  