Convert JSONArray to regular array

Question

I created a JSON array from a regular array of a user-defined object. How to convert JSONArray to a regular array of custom type.? I use Json for general preferences in android. I use this code I found on the net:

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

import android.content.Context;
import android.content.SharedPreferences;

public class JSONSharedPreferences {
    private static final String PREFIX = "json";

    public static void saveJSONObject(Context c, String prefName, String key, JSONObject object) {
        SharedPreferences settings = c.getSharedPreferences(prefName, 0);
        SharedPreferences.Editor editor = settings.edit();
        editor.putString(JSONSharedPreferences.PREFIX+key, object.toString());
        editor.commit();
    }

    public static void saveJSONArray(Context c, String prefName, String key, JSONArray array) {
        SharedPreferences settings = c.getSharedPreferences(prefName, 0);
        SharedPreferences.Editor editor = settings.edit();
        editor.putString(JSONSharedPreferences.PREFIX+key, array.toString());
        editor.commit();
    }

    public static JSONObject loadJSONObject(Context c, String prefName, String key) throws JSONException {
        SharedPreferences settings = c.getSharedPreferences(prefName, 0);
        return new JSONObject(settings.getString(JSONSharedPreferences.PREFIX+key, "{}"));
    }

    public static JSONArray loadJSONArray(Context c, String prefName, String key) throws JSONException {
        SharedPreferences settings = c.getSharedPreferences(prefName, 0);
        return new JSONArray(settings.getString(JSONSharedPreferences.PREFIX+key, "[]"));
    }

    public static void remove(Context c, String prefName, String key) {
        SharedPreferences settings = c.getSharedPreferences(prefName, 0);
        if (settings.contains(JSONSharedPreferences.PREFIX+key)) {
            SharedPreferences.Editor editor = settings.edit();
            editor.remove(JSONSharedPreferences.PREFIX+key);
            editor.commit();
        }
    }
}

I am trying to convert a user-defined array of objects to jsonarray and store it in jsonshared preference, and then try to extract it. Having a problem knowing how to extract it. Thank.

Answer 1

JSONObject, Android, JSONObject/JSONArray, . , , / JSON.

ProductLineItem lineItem = ...;
JSONObject json = new JSONObject();
json.put( "name", lineItem.getName() );
json.put( "quantity", lineItem.getCount() );
json.put( "price", lineItem.getPrice() );
... // do this for each property in your user defined class
String jsonStr = json.toString();

ProductLineItem.toJSON(). . , JSONObject : ProductLineItem obj = new ProductLineItem (jsonObject):

public class ProductLineItem {
    private String name;
    private int quantity;
    private float price;

   public MyObject( JSONObject json ) {
      name = json.getString("name");
      count = json.getInt("quantity");
      price = json.optFloat("price");
   }
}

. - :

public class ShoppingCart {

     float totalPrice;
     List<Rebate> rebates = new ArrayList<Rebate>();
     List<ProductLineItem> lineItems = new ArrayList<ProductLineItem>();


    public ShoppingCart( JSONObject json ) {
        totalPrice = json.getFloat("totalPrice");

        for( JSONObject rebateJson : json.getArray("rebates") ) {
            rebates.add( new Rebate( rebateJson ) );
        }

        for( JSONObject productJson : json.getArray("lineItems") ) {
            lineItems.add( new ProductLineItem( productJson ) );
        }
    }

    public JSONObject toJSON() {
        JSONObject json = new JSONObject();
        json.put("totalPrice", totalPrice );

        JSONArray rebatesArray = new JSONArray();
        for( Rebate rebate : rebates ) {
            rebatesArray.put( rebate.toJSON() );
        }

        JSONArray lineItemsArray = new JSONArray();
        for( ProductLineItem lineItem : lineItems ) {
            lineItemsArray.put( lineItem.toJSON() );
        }

        json.put( "rebates", rebatesArray );
        json.put( "lineItems", lineItemsArray );

        return json;
    }
}

2 , . , , :

http://flexjson.sourceforge.net

// serialize
String json = new JSONSerializer().serialize( shoppingCart );
// deserialize
ShoppingCart cart = new JSONDeserializer<ShoppingCart>().deserialize( json, ShoppingCart.class );

Answer 2

Google gson library . : http://code.google.com/p/google-gson/

Answer 3

I assume that your JSON array contains several instances of the same primitive type (string, int, float, etc. - if not, then you will have problems).

In this case, you need to do something like this (assuming an array of strings):

String[] strArray = new String[jsonArray.length()];

for (int i = 0; i < jsonArray.length(); i++) {
    strArray[i] = jsonArray.getString(i);
}

Obviously, if you are dealing with other primitive types, make appropriate replacements.