i want to load all the media contents, (images) in my wordpress site, to my android app using the JSON-API, i get it with retrieving the posts with JSON api, but what is with the images ?
You can do it easily by installing WP REST API plugin.
After the plugin is activated, make a GET request to example.com/wp-json/wp/v2/media. You will get all images info in JSON format.
This article might be helpful for you.
Make sure to change example.com to your actual domain.