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Android Application ID
boolean installed = appInstalledOrNot(Your App Package as String);

    if(installed){
           ////////App is Installed
    }

        private boolean appInstalledOrNot(String uri) {
            PackageManager pm = getPackageManager();
            try {
                pm.getPackageInfo(uri, PackageManager.GET_ACTIVITIES);
                return true;
            } catch (PackageManager.NameNotFoundException e) {
                return false;
            }

        }