Spinner not getting populated with database records in android

[Prashant Sontale]

Hi. I am using Yii2 REST API. I have a table called studentrecords consisting of Id,FirstName,LastName, Class fields. I have a API which returns the json array containing stiudent FirstName and LastName. API is working fine. Now I have a android code where I use a spinner to display student names from the database.

package com.example.anitaa.studentapplication;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ArrayAdapter;
import android.widget.Spinner;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.List;

public class UpdateActivity extends AppCompatActivity {
    Spinner spinner;
    ArrayAdapter adapter1;
    String url1 = "http://192.168.1.6/student/web/studentrecords/studentnames";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate ( savedInstanceState );
        setContentView ( R.layout.activity_update );
        spinner = (Spinner) findViewById ( R.id.spinner1 );
        final List<String> list = new ArrayList<String> ();

        try {
            JSONArray jsonarray=new JSONArray(url1);
            for(int i=0;i<jsonarray.length();i++)
            {

                JSONObject jsonObject = jsonarray.getJSONObject ( i );
                list.add(jsonObject.getString ( "FirstName"));
                list.add( jsonObject.getString ("LastName"));
            }
        } catch (JSONException e) {
            e.printStackTrace ();
        }

        adapter1=new ArrayAdapter ( this,android.R.layout.simple_spinner_item,list );
       // adapter1.setDropDownViewResource ( android.R.layout.simple_spinner_dropdown_item );
        spinner.setAdapter ( adapter1 );



    }
}

When I run it then spinner is not populated witth records. How to do?