What should I use to preload data using Volley on Android?

Question

I have some data stored in a database. In this case, users of the application.

I want to get all my information and place the layout of my application, so I need the data to be extracted using the function of onCreatemy layout class in order to display it when this layout changes.

I know about AsyncTaskand Volleyto execute asynchronous requests to my API, but in most cases not all users will be displayed on the layout, because they have not yet been extracted at the time the layout was displayed.

I also searched, and it seems that there are some ways (which sometimes seem to be workarounds) to make both AsyncTaskand Volleysynchronous, but they block UIThread.

I know the difference in requests asynchronousand synchronouswhy the second is blocking the application, so I have some questions.

• Is it always recommended to use asynchronous requests?
• If synchronous queries are bad, what is used when you need the data you retrieved from your database to be displayed at the same time as the layout?
• If I want this data to be available for the entire layout class, how can I handle it? I need to display data on the screen when rendering the layout, but I also want to do some things with it, so if I try to use it anywhere from the onResponseVolley request method , I always get it null. Something like "preloading" data.

Thanks in advance!

Answer 1

Finally, I notice that my problem is with concepts, because I thought you could not use the data obtained from the onResponsequery method Volley.

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String string = "";

, :

public void setString(String string){
    this.string = string;
}

, onResponse:

StringRequest jsonArrayRequest = new StringRequest(Request.Method.GET, url, new Response.Listener<String>() {
    @Override
    public void onResponse(String response) {
        try {
           //Do stuff to retrieve the String
           setString(response); //Assign the string "response" to the global variable via the method.
        } catch (JSONException e) {
              e.printStackTrace();
        }
    }
}, new Response.ErrorListener() {
    @Override
    public void onErrorResponse(VolleyError error) {
         Log.e("LOG", error.toString());
    }
});

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Answer 2

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Answer 3

PreLoader: https://github.com/luckybilly/PreLoader

Volley Activity Activity.onCreate() preLoaderId.