SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO SET ANSI_PADDING ON

GOCREATETABLE A_Ciudades ( [IdCiudad] [int] NOT NULL, [NombreCiudad] [varchar](35)

 NOT NULL, PRIMARY KEY CLUSTERED  ( [IdCiudad] ASC )WITH (PAD_INDEX = OFF,

STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON,

ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO SET ANSI_PADDING OFF GO

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Web;
using System.Text;
using System.Data;
using System.Data.SqlClient;

namespace WcfService1
{
public class Service1 : IService1
{
private string conStr = "Data Source =.; Initial Catalog=.; uid=sa; pwd=.";

public List<A_Ciudades> GetA_Ciudades()
{
List<A_Ciudades> A_CiudadesList = new List<A_Ciudades>();
    SqlConnection connection = new SqlConnection(this.conStr);
connection.Open();
SqlCommand cmd = new SqlCommand("select NombreCiudad from A_Ciudades order by IdCiudad desc", connection);
cmd.CommandType = CommandType.Text;
SqlDataReader sdr = cmd.ExecuteReader();
while (sdr.Read())
 {
A_Ciudades rha = new A_Ciudades ();
rha.NombreCiudad= sdr["NombreCiudad"].ToString();
A_CiudadesList.Add(rha);
}
return A_Ciudades List.ToList();
}
}
}

IService1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Web;
using System.Text;
using System.Data;
using System.Data.SqlClient;

namespace WcfService1
{
[ServiceContract]
public interface IService1
{

[OperationContract]
[WebGet(UriTemplate = "GetA_Ciudades")]
List<A_Ciudades> GetA_Ciudades ();
}
 [DataContract]
public class A_Ciudades
{
string nombreciudad; [DataMember] public string NombreCiudad { get { return nombreciudad; } set { nombreciudad = value; } }
}
}

<android.support.design.widget.AppBarLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:theme="@style/AppTheme.AppBarOverlay">
        <android.support.v7.widget.Toolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            android:background="?attr/colorPrimary"
            app:popupTheme="@style/AppTheme.PopupOverlay">
            <TextView
                android:id="@+id/date"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text=""
                android:textColor="@color/colorTexto"
                android:textSize="20sp"
            />
        </android.support.v7.widget.Toolbar>
    </android.support.design.widget.AppBarLayout>
<include layout="@layout/ cont_ciudades"/>

<GridView
            android:id="@+id/txtGrid"
            android:paddingLeft="6dp"
            android:paddingRight="6dp"
            android:paddingTop="6dp"
            android:paddingBottom="6dp"
            android:verticalSpacing="6dp"
            android:layout_width="wrap_content"
            android:layout_height="180dp"
            android:layout_gravity="center"
            android:animationCache="true"
            android:columnWidth="180dp"
            android:isScrollContainer="false"
            android:numColumns="2"
            android:stretchMode="spacingWidth"
            android:textFilterEnabled="false"
            tools:layout_editor_absoluteX="8dp"
            tools:layout_editor_absoluteY="8dp"
            android:layout_alignParentBottom="true"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true”>
        </GridView>

<TextView
    android:id="@+id/txtNombre"
    style="@android:style/Widget.Button.Inset"
    android:layout_width="178dp"
    android:layout_height="36dp"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_alignParentTop="true"
    android:gravity="center"
    android:text="Nombre Ciudad"
    android:textAppearance="@style/TextAppearance.AppCompat"
    android:textColor="@color/colorPrimaryDark"
    android:textSize="14dp"
    android:textStyle="bold" />

<TextView
    android:id="@+id/txtNombreCiudad"
    android:layout_width="89dp"
    android:layout_height="24dp"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_below="@+id/ txtNombre "
    android:gravity="bottom|center"
    android:text="  "
    android:textAppearance="@style/TextAppearance.AppCompat"
    android:textColor="@color/colorFondo"
    android:textSize="14dp"
    android:textStyle="bold" />

<ImageView
    android:id="@+id/txtImg"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/ txtNombre "
    android:layout_toEndOf="@+id/ txtNombreCiudad "

import android.app.Activity;
import android.content.Intent;
import android.os.AsyncTask;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Button;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.ListAdapter;
import android.widget.SimpleAdapter;
import android.widget.TextView;
import android.widget.Toast;
import org.json.JSONArray;
import org.json.JSONObject;
import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.HashMap;

public class Ciudades extends AppCompatActivity {

    ArrayList<HashMap<String, String>> CiudGrid;
    ListAdapter adapter;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.ciudades);


        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        ActionBar actionBar = getSupportActionBar();
        actionBar.setDisplayHomeAsUpEnabled(true);

        Thread t = new Thread() {
            @Override
            public void run() {
                try {
                    while (!isInterrupted()) {
                        Thread.sleep(500);
                        runOnUiThread(new Runnable() {
                            @Override
                            public void run() {
                                TextView tdate = (TextView) findViewById(R.id.date);
                                long date = System.currentTimeMillis();
                                SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
                                String dateString = sdf.format(date);
                                tdate.setText(dateString);
                            }
                        });
                    }
                } catch (InterruptedException e) {
                }
            }
        };
        t.start();


        CiudGrid = new ArrayList<HashMap<String, String>>();
        GridView Grid = (GridView) findViewById(R.id.txtGrid);
        new GetA_CiudadesList(Ciudades.this,Grid).execute("http://0.0.0.00:0000/service1.svc/GetA_Ciudades");

    }

    class GetA_CiudadesList extends AsyncTask<String, Void, String> {
        String status= null;
        Activity context;
        GridView gridView;


        public GetA_CiudadesList(Activity context, GridView gridView){
            this.context =context;
            this.gridView=gridView;
        }

        protected void onPreExecute(){


        }

        protected String doInBackground(String... connUrl){
            HttpURLConnection conn=null;
            BufferedReader reader;
            try{
                final URL url=new URL(connUrl[0]);
                conn=(HttpURLConnection) url.openConnection();
                conn.addRequestProperty("Content-Type", "application/json; charset=utf-8");
                conn.setRequestMethod("GET");
                int result = conn.getResponseCode();
                if(result==200){
                    InputStream in=new BufferedInputStream(conn.getInputStream());
                    reader = new BufferedReader(new InputStreamReader(in));
                    StringBuilder sb=new StringBuilder();
                    String line = null;
                    while((line=reader.readLine())!=null){
                        status=line;
                    }
                }
            }catch(Exception ex){
                ex.printStackTrace();
            }
            return status;
        }

        protected void onPostExecute(String result){
            super.onPostExecute(result);
            if(result!=null){

                try{
                    ArrayList<String> stringArrayList = new ArrayList<String>();
                    JSONArray jsonArray = new JSONArray(result);
                    for(int i=0; i<jsonArray.length(); i++){
                        JSONObject object = jsonArray.getJSONObject(i);
                        String NombreCiudad= object.getString("NombreCiudad");
                        HashMap<String, String> itemList = new HashMap<String, String>();
                        itemList.put("NombreCiudad",NombreCiudad);
                        CiudGrid.add(itemList);
                    }
                    adapter = new SimpleAdapter(Ciudades.this, CiudGrid,R.layout.ciudades_list,

                            new String[]
                                      {
                                              "NombreCiudad"
                                      },
                              new int[]
                                      {
                                              R.id.txtNombreCiudad,

                                      });


                    ((AdapterView<ListAdapter>) gridView).setAdapter(adapter);

                }catch (Exception ex){
                    ex.printStackTrace();
                }
            }else{
                Toast.makeText(A5_0_Result_Anim_Trad.this,"Could not get any data.",Toast.LENGTH_LONG).show();
            }

        }

    }
}