Problema ao carregar varias imagem

private ListView viewlist;
private List<AuxAdapter> listaadap = new ArrayList<AuxAdapter>();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

   ... código ...

    viewlist = (ListView) findViewById(R.id.viewlista);

    new Thread(new Runnable() {
        @Override
        public void run() {
            PegaGet();
        }
    }).start();
}

public void PegaGet(){
    try {
        Conexao cx = new Conexao();
        String json = cx.Conec("get",0, null, null, null, false); //<= aqui ele só retorna um Json em forma de String

        listaadap = null;
        listaadap = cx.LerJson(json);

        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                AdapterLista ad = new AdapterLista(contesto, listaadap, ma);//<= contesto = Context ; ma = é um objeto do MainActivity 
                viewlist.setAdapter(ad);
            }
        });
    } catch (JSONException e) {
        e.printStackTrace();
    } catch (MalformedURLException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

public List<AuxAdapter> LerJson(String json){
    List<AuxAdapter> li = new ArrayList<AuxAdapter>();
    try {
        JSONObject jo = new JSONObject(json);
        JSONArray ja = jo.getJSONArray("lista");

        for(int i = 0 ; i < ja.length() ; i++ ){
            AuxAdapter adp = new AuxAdapter();
            jo = null;
            jo = ja.getJSONObject(i);

            adp.setId(jo.getInt("id"));
            adp.setNome(jo.getString("nome"));
            adp.setDescricao(jo.getString("descricao"));
            adp.setValor(jo.getDouble("valor"));
            adp.setImagem(Carregaimagem(jo.getInt("id")));
            adp.setNomeDoArquivo(jo.getString("nomeDoArquivo"));
            adp.setTipo(jo.getString("tipo"));

            li.add(adp);

        }

    } catch (JSONException e) {
        li.clear();
        e.printStackTrace();
    }

    return li;
}

public Bitmap Carregaimagem(int id){
    Bitmap ima = null;
    HttpURLConnection co = null;
    try{
        URL url = new URL("http://192.168.0.105:8080/WebServiceAppMaven/androidima/"+id);
        co = (HttpURLConnection) url.openConnection();
        co.setUseCaches(false);
        co.setDoInput(true);
        //co.setDoOutput(false);
        co.setRequestMethod("GET");
        co.connect();
        InputStream in = co.getInputStream();
        ima = BitmapFactory.decodeStream(in);
    }catch (IOException e){
        e.printStackTrace();
    }finally {
        co.disconnect();
    }
    return ima;
}