/**
   * Returns the current usage stats list, if the user enable the option in the settings menu.
   *
   * @param context Context, the current context
   * @return List<UsageStats>
   */
  @TargetApi(Build.VERSION_CODES.LOLLIPOP)
  public static List<UsageStats> getUsageStatsList(Context context) {
    UsageStatsManager usm = getUsageStatsManager(context);
    Calendar calendar = Calendar.getInstance();
    long endTime = calendar.getTimeInMillis();
    calendar.add(Calendar.YEAR, -1);
    long startTime = calendar.getTimeInMillis();

    List<UsageStats> usageStatsList =
        usm.queryUsageStats(UsageStatsManager.INTERVAL_DAILY, startTime, endTime);
    return usageStatsList;
  }
 /**
  * @param context context
  * @return アプリケーションの使用状況のアクセス許可設定がONの場合true
  */
 public static boolean isUsageStatsAccessible(Context context) {
   UsageStatsManager usageStatsManager =
       (UsageStatsManager) context.getSystemService(Context.USAGE_STATS_SERVICE);
   Calendar calendar = Calendar.getInstance();
   calendar.set(
       calendar.get(Calendar.YEAR),
       calendar.get(Calendar.MONTH),
       calendar.get(Calendar.DATE),
       0,
       0,
       0);
   List<UsageStats> usageStatsList =
       usageStatsManager.queryUsageStats(
           UsageStatsManager.INTERVAL_DAILY,
           calendar.getTimeInMillis(),
           calendar.getTimeInMillis() + 24 * 60 * 60 * 1000);
   return usageStatsList.size() != 0;
 }