Trying to read 2D array from Json to Android

Question

I have a problem reading my Json document because I want to read a 2d array looking like this:

"map" : [ ["PARED", "PARED", "PARED", "PARED", "PARED" , "PARED" , "PARED" , "PARED" , "PARED" , "PARED"], ["PARED" , "SNOWMAN" , "ESPACIO" , "PARED" , "ESPACIO" , "ESPACIO" , "ESPACIO" , "ESPACIO" , "ESPACIO" , "PUERTA"], ["PARED" , "ESPACIO" , "SOL" , "PARED" , "PARED" , "PARED" , "ESPACIO" , "PARED" , "ESPACIO" , "PARED"], ["PARED" , "ESPACIO" , "PARED" , "PARED" , "SOL" , "ESPACIO" , "ESPACIO" , "ESPACIO" , "ESPACIO" , "PARED"], ["PARED" , "ESPACIO" , "PARED" , "ESPACIO" , "ESPACIO" , "ESPACIO" , "SOL" , "ESPACIO" , "PARED" , "PARED"], ["PARED" , "ESPACIO" , "PARED" , "PARED" , "ESPACIO" , "PARED" , "PARED" , "ESPACIO" , "PARED" , "PARED"], ["PARED" , "ESPACIO" , "ESPACIO" , "ESPACIO" , "ESPACIO" , "PARED" , "SOL" , "ESPACIO" , "ESPACIO" , "PARED"], ["PARED" , "SOL" , "PARED" , "ESPACIO" , "PARED" , "PARED" , "ESPACIO" , "ESPACIO" , "SOL" , "PARED"], ["PARED" , "ESPACIO" , "ESPACIO" , "ESPACIO" , "ESPACIO" , "ESPACIO" , "ESPACIO" , "PARED" , "ESPACIO" , "PARED"], ["PARED" , "PARED" , "PARED" , "PARED" , "PARED" , "PARED" , "PARED" , "PARED" , "PARED" , "PARED"] ]

And convert it to a "String [][] mapa;" array in Android Studio, but I don't know how to read and cast it.

I really apreciate your help.

EDIT: I tried something like this, but I don't know how to continue:

mapObject.getJSONArray("map")

EDIT2 something like that?:

JSONArray mapatest = mapObject.getJSONArray("map");

            String[][] innerArray = null;

            for(int t = 0; t < mapatest.getCount(); t++){

                innerArray[t] = mapatest.getJSONArray(t);

                for(int k = 0; k < innerArray.getCount(); t++){

                    innerArray[t][k] = mapatest.getString(k);

                }
            }

see my answer, this way is simple and quick - stackoverflow.com/questions/33720204/… — Vladimir Markeev
– Vladimir Markeev, Commented Nov 17, 2015 at 20:55
try to get it with Retrofit (see link above) and you will not parse array — Vladimir Markeev
– Vladimir Markeev, Commented Nov 17, 2015 at 21:16

Marcos Vasconcelos · Accepted Answer · 2015-11-17 20:28:25Z

1

While mapObejct.getJSONArray("map") returns an array where each entry is the X of your table, each item of the array will be an Array itself (getJSONArray again) and will be your Y of the table.

The code would looks like:

map = obj.getJSONArray("map);
for(int i = 0; i < map.getCount(); i++){
   innerArray = map.getJSONArray(i);
   for(int k = 0; k < innerArray.getCount(); i++){
      innerItem = map.getString(k);
   }      
}

This will navigate trought i,k where they would be your array[i][k]

EDIT: With your code:

 JSONArray mapatest = mapObject.getJSONArray("map");
        String[][] innerArray = null;

        for(int t = 0; t < mapatest.getCount(); t++){
            JSONArray innerArrayObj = mapatest.getJSONArray(t);
            innerArray[t] = new String[innerArrayObj.getCount());

            for(int k = 0; k < innerArrayObj.getCount(); t++){

                innerArray[t][k] = innerArrayObj.getString(k);

            }
        }

edited Nov 17, 2015 at 20:28

answered Nov 17, 2015 at 19:25

Marcos Vasconcelos

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5 Comments

Souloibur Over a year ago

I think I am not understanding it, I have this but it doesn't work. Thank you for your help. (I can't post code here, so I'll put it in the question.)

Marcos Vasconcelos Over a year ago

Oh.. one miss, check the answer

Souloibur Over a year ago

Yes it seems it will work, but I have an error in getCount(). "Cannot resolve method"

Souloibur Over a year ago

I've changed "getCount()" to "length()" but now I have this error: E/AndroidRuntime: Caused by: java.lang.NullPointerException: Attempt to write to null array In this line: innerArray[t] = new String[innerArrayObj.length()];

Marcos Vasconcelos Over a year ago

You must add innerArray = new String[mapatest.getCount()][]; before the for

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