How to check String in Hash map?

class LoadContentFromServer extends AsyncTask<Object, Integer, Object>{
		@Override
		protected Object doInBackground(Object... params) {
			// TODO Auto-generated method stub
			String url = "http://192.168.1.109/Wow/?Type=go1";
			String ckCode = "";
			JSONObject data;
			JSONArray dataset;
			myArrList = new ArrayList<HashMap<String, Object>>();
			
			try {
				data = new JSONObject(getJSONUrl(url));
				dataset = data.getJSONArray("stock");
				myArrList = new ArrayList<HashMap<String,Object>>();
				List = new ArrayList<String>();
				HashMap<String, Object> map;
				for (int i = 0 ; i < dataset.length(); i ++){
						JSONObject c1 = dataset.getJSONObject(i);
						map = new HashMap<String, Object>();
						myArrList.add(map);
						map.put("code", c1.getString("code").toString());
						publishProgress(i);
						
					}
				}
			} catch (Exception e) {
				// TODO: handle exception
			}
			return null;
		}

public void next(View view){
        Intent nextScreen = new Intent(getApplicationContext(), FragmentGO.class);
        if(  ){
            startActivity(nextScreen);
        }
        else{
	    Toast.makeText(getApplicationContext(),"NOT FOUND",Toast.LENGTH_LONG).show();
	}
    }