Reading data from json array to plot in graph

Question

So I am using the MPandroid chart dependency to plot the graph on an android app. For this I am adding data to an ArrayList of class Entry of the graph. I am adding the data manually for now but I want to parse a the data from a json file and add it to graph. can anyone tell me how can I read individual data elements of Json array to add to graph.

This is the code I am using to read the json file.I have the file in my asset folder.

  try {
        InputStream is=getAssets().open("gaitdata.json");
        int size=is.available();
        byte[] buffer=new byte[size];
        is.read(buffer);
        is.close();
        json=new String(buffer,"UTF-8");
        JSONArray jsonArray=new JSONArray(json);

            for(int i=0;i<jsonArray.length();i++){
                JSONObject obj=jsonArray.getJSONObject(i);
                if(obj.getString("name").equals("kinematics")){
                    hipvalue.add(obj.getString("hip_min"));


              }
            }

Also this is the json file I want to read.

{
 "name":"kinematics",
 "hip_min":[1.2,5.67,2.34,6.8]
}

Also I want the float value but since it is not working so I have used obj.getString() to get the "hip_min" value for json.

And Lastly this is how I add data manually to Array list.

ArrayList<Entry> entries=new ArrayList<>();
        entries.add(new Entry(0,19.85f));

Abdul · Accepted Answer · 2019-07-11 12:48:28Z

0

For converting the Json Arry to floating Array you can try the following code .

   String value = "{'name':'kinematics','hip_min':[1.2,5.67,2.34,6.8]}";
        JSONObject obj = new JSONObject(value);
        List hip_min = new ArrayList<Float>();
        JSONArray jsonArray;

        jsonArray = obj.getJSONArray("hip_min");

        for (Object item : jsonArray
        ) {
            hip_min.add(item);
        }
        System.out.println("Size : " + hip_min.size());

And for Chart

 int i=0;
        for (Object item:hip_min
             ) {
            entries.add(new Entry(i,item))
                    i=i+2;


        }

the value of i is for horizontal shift. i hope that will help.

answered Jul 11, 2019 at 12:48

Abdul

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2 Comments

Kundan Jha Over a year ago

the part: for(Object item : jsonArray) give me error as "foreach not applicable to type 'org.json.JSONArray'. What shall I do?

Kundan Jha Over a year ago

Ok I will try it!!

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