content: /*
   * Copyright (C) 2017 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.android.server.backup.utils;
  
  import android.util.SparseArray;
  
  import java.util.HashSet;
  
  /**
   * Helper functions for manipulating instances of {@link SparseArray}.
   */
  public final class SparseArrayUtils {
      // Statics only
      private SparseArrayUtils() {}
  
      /**
       * Given a {@link SparseArray<HashSet>}, returns a new {@link HashSet} containing every element
       * from every set in the array.
       *
       * @param sets The array of sets from which to take the union.
       * @param <V> The type of element contained in the set.
       * @return The complete set.
       */
      public static<V> HashSet<V> union(SparseArray<HashSet<V>> sets) {
          HashSet<V> unionSet = new HashSet<>();
          int n = sets.size();
          for (int i = 0; i < n; i++) {
              HashSet<V> ithSet = sets.valueAt(i);
              if (ithSet != null) {
                  unionSet.addAll(ithSet);
              }
          }
          return unionSet;
      }
  }
  