how to parse JSONArray in android NullPointerException

Question

I want to parse jsonObject passed by another activity

intent.putextra("result", json.toString());

It shows everything right with name, branch and session. but it shows NullPointerException while fetching array. at here

            mSubList.add(map);

this array has 6 rows. this is my code. please tell me exactly where Im wrong.

JSONObject json;
ListView sub_list;

private JSONArray mComments = null;
private ArrayList<HashMap<String, String>> mSubList;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_result_page);

    name = (TextView)findViewById(R.id.name_roll);
    branch= (TextView)findViewById(R.id.branchname);
    session = (TextView)findViewById(R.id.Session);

    sub_list = (ListView)findViewById(R.id.sub_list);



    try {
         json = new JSONObject(getIntent().getStringExtra("result"));

        name.setText(json.getString("REGNO")+" - "+json.getString("STUDENTNAME"));
        branch.setText(json.getString("BRANCHNAME"));
        session.setText(json.getString("SESSIONNAME"));

        mComments = json.getJSONArray("DATA");

        // looping through all subjects according to the json object returned
        for (int i = 0; i < mComments.length(); i++) {
            JSONObject c = mComments.getJSONObject(i);

            // gets the content of each tag
            String code = c.getString("CCODE");
            String subject = c.getString("COURSENAME");
            String passfail = c.getString("PASSFAIL");

            // creating new HashMap
            HashMap<String, String> map = new HashMap<String, String>();

            map.put("CCODE", code);
            map.put("COURSENAME", subject);
            map.put("PASSFAIL", passfail);
            // adding HashList to ArrayList
            mSubList.add(map);
        }

                ListAdapter adapter = new SimpleAdapter(this, mSubList,
                R.layout.singlesubject, new String[] { "CCODE", "COURSENAME",
                "PASSFAIL" }, new int[] { R.id.sub_id, R.id.sub_name,R.id.sub_res });

        sub_list.setAdapter(adapter);
    }catch(Exception e){
        e.printStackTrace();
    }
  }
}

if I want to change each listitem background(R.layout.singlesubject) if "PASSFAIl"=P then Green color else Red color. then what changes i have to do ?

mSubList is null you need to initialize it before adding map — ρяσѕρєя K
– ρяσѕρєя K, Commented Jan 10, 2015 at 15:25
if I want to change each listitem background(R.layout.singlesubject) if "PASSFAIl"=P then Green color else Red color. then what changes i have to do ? — akshay bhange
– akshay bhange, Commented Jan 10, 2015 at 15:59
@akshey: if you want to change ListView rows color then create custom adapter by extending BaseAdpter,SimpleAdapter,.. . currently you are using default SimpleAdapter implementation so it's not possible without creating custom adapter — ρяσѕρєя K
– ρяσѕρєя K, Commented Jan 10, 2015 at 16:03

Josh Engelsma · Accepted Answer · 2015-01-10 15:25:54Z

2

mSubList.add(map);

this line of code is failing because you do not initialize the array before adding the map

You can initialize it by using...

mSubList = new ArrayList<Hashmap<String, String>>();

answered Jan 10, 2015 at 15:25

Josh Engelsma

2,64616 silver badges17 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

akshay bhange Over a year ago

if I want to change each listitem background(R.layout.singlesubject) if "PASSFAIl"=P then Green color else Red color. then what changes i have to do ?

SorryForMyEnglish · Accepted Answer · 2015-01-10 15:27:46Z

1

init your mSubList before add item

mSubList = new ArrayList<HashMap<String, String>>();

answered Jan 10, 2015 at 15:27

SorryForMyEnglish

1,1917 silver badges14 bronze badges

Comments

Max Klein · Accepted Answer · 2015-01-10 15:27:53Z

1

I think you forgot to initialize mSubList before adding data to it:

mSubList = new ArrayList<HashMap<String, String>>();

answered Jan 10, 2015 at 15:27

Max Klein

5281 gold badge7 silver badges23 bronze badges

Collectives™ on Stack Overflow

how to parse JSONArray in android NullPointerException

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related