Check if a app is instlled

In the last two posts Start a specified app and Start a specified app with data passed, it's assumed that the slave app is installed. In order to check if it's installed, we can call PackageManager.queryIntentActivities().

	private void startSlave(String passingText){

   	Intent intent = new Intent();

   	intent.setClassName(PACKAGE_NAME, CLASS_NAME);

   	

   	Bundle bundle = new Bundle();

   	bundle.putString("key", passingText);

       intent.putExtras(bundle);

   	

       //check if the slave app installed

       List<ResolveInfo> list = getPackageManager().queryIntentActivities(

       		intent,  

               PackageManager.MATCH_DEFAULT_ONLY); 



       if (list.size() >0 ){

       	//Yes, the Slave App installed

       	startActivity(intent);

       }else{

       	//No!

       	Toast.makeText(AndroidMasterActivity.this,

       			"Slave App not yet installed!",

       			Toast.LENGTH_LONG).show();

       }	

   }

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