Question

Can someone please tell my why I’m getting a null pointer exception with this code? In my Nutrition class, I implement a hash map:

public class Nutrition implements Serializable{

private final String TAG = Nutrition.class.getSimpleName();
//class variables
    ...

//hash map declaration
HashMap<String, String> nutrition; 

public Nutrition(JSONObject jo) throws JSONException{

    //create hash map
    this.nutrition = new HashMap<String, String>(); 



    //place data in hashmap
    this.serving_size = jo.optString("serving_size");
    nutrition.put("serving_size", serving_size); 
    Log.i(TAG, serving_size + " : Serving Size");
           ....
    }
   //method to get hashmap
   public HashMap<String, String> getHashMap(){
    return nutrition; 
}

Then in another class, I call getHashMap() and I get a null pointer:

//nutrition item
    Nutrition nutritionInfo  = dish.getNutrition();
    nutInfo = nutritionInfo.getHashMap(); 

Can someone tell me what I’m doing wrong and how I can fix it?

Answer 1

The second line will throw an NPE if dish.getNutrition() returns null.

Nutrition nutritionInfo  = dish.getNutrition();
nutInfo = nutritionInfo.getHashMap(); 

Since you haven’t shown us the code in the Dish class, I would assume it occurs here.