Why does an “Intent Selector” exists, what is it used for?

Question

Android\'s Intent class provides an API called setSelector. I am trying to understand it from the example given in the documentation.

I want to ask tha

Answer 1

According to my understanding, it gives choice to user which intent he wants to select. In that documentation they have given that it gives selection of intents whether user wants to open app's main activity or wants to launch any diff app/activity other than user's app. This is what i understood from that documentation. Check this links for your reference : https://code.google.com/p/android/issues/detail?id=67162 & http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/4.4_r1/android/content/Intent.java#Intent.setSelector%28android.content.Intent%29

Answer 2

My understanding from reading the references is that the problem this API is intending to solve is where you want to send a launcher intent for an app that meets some general restrictions. Say you want to match all apps that open .mp3 files, but you don't want to actually open an mp3 file, you just want to launch an app that supports that. In that case, you could create a generic ACTION_MAIN, CATEGORY_LAUNCHER intent, and set the selector to an intent with an mp3 mime type or data URI.

Before this API there would be no way to do that - if you wanted to target an app that supports opening mp3s, you would have to send an intent for an mp3, which could either cause music to start playing, or cause the music player to throw an error. Also, depending on the music player's launch mode, the launcher intent may return to an existing instance of the music player, while the mp3 intent might create a new one.