Styjun

I am a newbie to android. I am developing an app locker that uses face id instead of normal pin/pattern using kotlin.
I have got the list of installed apps in the system. But, how to get the information about which app is opened using service Please help.

Like this:

Java version

 private String retriveAppInForeground() 
 String currentApp = null;
 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1) 
 UsageStatsManager usm = (UsageStatsManager) this.getSystemService(Context.USAGE_STATS_SERVICE);
 long time = System.currentTimeMillis();
 List<UsageStats> appList = null;
 if (usm != null) 
 appList = usm.queryUsageStats(UsageStatsManager.INTERVAL_DAILY, time - 1000 * 1000, time);
 
 if (appList != null && !appList.isEmpty()) 
 SortedMap<Long, UsageStats> sortedMap = new TreeMap<>();
 for (UsageStats usageStats : appList) 
 sortedMap.put(usageStats.getLastTimeUsed(), usageStats);
 
 if (!sortedMap.isEmpty()) 
 currentApp = sortedMap.get(sortedMap.lastKey()).getPackageName();
 
 
 else 
 ActivityManager am = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
 if (am != null) 
 currentApp =(am.getRunningTasks(1).get(0)).topActivity.getPackageName();
 
 
 Log.e("ActivityTAG", "Application in foreground: " + currentApp);
 return currentApp;
 

Kotlin version

 private fun retriveAppInForeground(): String? 
 var currentApp: String? = null
 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1) 
 val usm = this.getSystemService(Context.USAGE_STATS_SERVICE) as UsageStatsManager
 val time = System.currentTimeMillis()
 val appList: List<UsageStats>?
 appList = usm.queryUsageStats(UsageStatsManager.INTERVAL_DAILY, time - 1000 * 1000, time)
 if (appList != null && appList.isNotEmpty()) 
 val sortedMap = TreeMap<Long, UsageStats>()
 for (usageStats in appList) 
 sortedMap.put(usageStats.lastTimeUsed, usageStats)
 
 currentApp = sortedMap.takeIf it.isNotEmpty() ?.lastEntry()?.value?.packageName
 
 else 
 val am = getSystemService(Context.ACTIVITY_SERVICE) as ActivityManager
 @Suppress("DEPRECATION") //The deprecated method is used for devices running an API lower than LOLLIPOP
 currentApp = am.getRunningTasks(1)[0].topActivity.packageName
 
 Log.e("ActivityTAG", "Application in foreground: " + currentApp)
 return currentApp
 

Make sure your app has the proper permissions for accessing the usage stats:

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

And that the user grants the proper permission, you can take the user to the proper settings screen to enable the permission (when setting up your app):

startActivity(new Intent(Settings.ACTION_USAGE_ACCESS_SETTINGS));

And one more thing, always make sure you search for any similar question before posting a new one.