[Android Pro] How to get recent tasks on Android “L”?

<uses-permission android:name="android.permission.PACKAGE_USAGE_STATS" />

String topPackageName ;
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
UsageStatsManager mUsageStatsManager = (UsageStatsManager)getSystemService("usagestats");
long time = System.currentTimeMillis();
// We get usage stats for the last 10 seconds
List<UsageStats> stats = mUsageStatsManager.queryUsageStats(UsageStatsManager.INTERVAL_DAILY, time - 1000*10, time);
// Sort the stats by the last time used
if(stats != null) {
SortedMap<Long,UsageStats> mySortedMap = new TreeMap<Long,UsageStats>();
for (UsageStats usageStats : stats) {
mySortedMap.put(usageStats.getLastTimeUsed(),usageStats);
}
if(mySortedMap != null && !mySortedMap.isEmpty()) {
topPackageName =  mySortedMap.get(mySortedMap.lastKey()).getPackageName();
}
}
}