content: /**
   * Copyright 2015-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * A copy of the License is located at
   *
   *     http://aws.amazon.com/apache2.0/
   *
   * or in the "license" file accompanying this file. This file 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.amazon.utils;
  
  import org.json.JSONArray;
  import org.json.JSONException;
  
  import android.util.Log;
  
  import java.util.ArrayList;
  import java.util.LinkedHashSet;
  import java.util.List;
  import java.util.Map;
  
  /**
   * Utilities for Lists.
   */
  public class ListUtils {
  
      private static final String TAG = ListUtils.class.getSimpleName();
  
      /**
       * Add the item to the list if the item is not already in the list.
       *
       * @param list List.
       * @param item Item to add to the list.
       * @param <T>  Item type.
       * @return True if the item was added, false otherwise.
       */
      public static <T> boolean safeAdd(List<T> list, T item) {
  
          if (list.contains(item)) {
              return false;
          }
          return list.add(item);
      }
  
      /**
       * Remove duplicate items from the given list. Return the result as a new list and don't modify
       * the original list.
       *
       * @param list List to remove duplicates from.
       * @param <T>  Item type.
       * @return A new list that contains the items of the original list without any duplicates.
       */
      public static <T> List<T> removeDuplicates(List<T> list) {
  
          return new ArrayList<>(new LinkedHashSet<>(list));
      }
  
      /**
       * Turns a string to a list. The items within the string should be separated by commas.
       * Example,
       * the string "one, two, three" will return a list with three items ["one", "two", "three"].
       *
       * @param string The string to turn into a list.
       * @return The list, an empty array if there was an error, or null if the input is null.
       * @throws ExpectingJsonArrayException if the string is not in a JSONArray format.
       */
      public static List<String> stringToList(String string) throws ExpectingJsonArrayException {
  
          if (string == null) {
              return null;
          }
  
          List<String> list = new ArrayList<>();
          try {
              JSONArray jsonArray = new JSONArray(string);
              for (int i = 0; i < jsonArray.length(); i++) {
                  list.add(jsonArray.getString(i));
              }
          }
          catch (JSONException e) {
              throw new ExpectingJsonArrayException(string);
          }
          return list;
      }
  
      /**
       * Get a map value from a map using a key and return it as a list.
       *
       * @param map The map to get the map value from.
       * @param key The key to get the map value.
       * @return A list of maps.
       */
      public static List<Map> getValueAsMapList(Map<String, Map> map, String key) {
  
          if (map == null || StringManipulation.isNullOrEmpty(key) || map.get(key) == null) {
              return new ArrayList<>();
          }
          if (map.get(key) instanceof List) {
              return (List<Map>) map.get(key);
          }
          List<Map> list = new ArrayList<>();
          list.add(map.get(key));
          return list;
      }
  
      /**
       * An error message for when a content's member variable is expected to be a string
       * representation of a JSON array but is something else.
       */
      public static class ExpectingJsonArrayException extends Exception {
  
          /**
           * Constructor.
           *
           * @param wrongValue The value used instead of a string representation of a JSON array.
           */
          public ExpectingJsonArrayException(String wrongValue) {
  
              super("Expecting a string representation of a JSON array but got: " + wrongValue);
          }
      }
  }
  