How to detect foreground process name in Android with Lollipop

lollipop.java

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public static String getForegroundProcess(Context context) {
        String topPackageName = null;
        UsageStatsManager usage = (UsageStatsManager) context.getSystemService(Context.USAGE_STATS_SERVICE);
        long time = System.currentTimeMillis();
        List<UsageStats> stats = usage.queryUsageStats(UsageStatsManager.INTERVAL_DAILY, time - 1000*1000, time);
        if (stats != null) {
            SortedMap<Long, UsageStats> runningTask = new TreeMap<Long,UsageStats>();
            for (UsageStats usageStats : stats) {
                runningTask.put(usageStats.getLastTimeUsed(), usageStats);
            }
            if (runningTask.isEmpty()) {
                return null;
            }
            topPackageName =  runningTask.get(runningTask.lastKey()).getPackageName();
        }
        if(topPackageName==null) {
            Intent intent = new Intent(Settings.ACTION_USAGE_ACCESS_SETTINGS);
            context.startActivity(intent);
        }

        return topPackageName;
    }