1) If your requirement is to get app icon from package name then below few lines of code will be helpful for you.

try
    {
       Drawable app_icon = getPackageManager().getApplicationIcon("PACKAGE_NAME");
       my_imageView.setBackgroundDrawable(app_icon);
    }
    catch (PackageManager.NameNotFoundException e)
    {
        return;
    }

2) To launch particular app knowing only its package name

PackageManager pm = context.getPackageManager();
Intent launchIntent = pm.getLaunchIntentForPackage("PACKAGE_NAME");

	if (launchIntent != null) {

	    context.startActivity(launchIntent);
	} else {

	    Toast.makeText(context, "Package not found", Toast.LENGTH_SHORT).show();
	}

3) We can get last updated time of particular app.

try {
		packageInfo = getPackageManager().getPackageInfo(getPackageName(), 0);
	} catch (PackageManager.NameNotFoundException e) {
		e.printStackTrace();
	}

	lastUpdateTime = packageInfo.lastUpdateTime;
	elapsed = ((System.currentTimeMillis() - lastUpdateTime) / 1000);
	
	lastUpdateTotalTime = String.format("%02d:%02d:%02d", elapsed / 3600, (elapsed % 3600) / 60, (elapsed % 60));
	Log.d("Last Update Time:",lastUpdateTotalTime);

4) We can get list of activities used in application using package name

 try {
         PackageInfo pi = getPackageManager().getPackageInfo("PACKAGE_NAME", PackageManager.GET_ACTIVITIES);

         mActivities = new ArrayList<ActivityInfo>(Arrays.asList(pi.activities));

     } catch (PackageManager.NameNotFoundException e) 
     {
         return;
     }