Displaying image retrieved from server

Question

I am working on an Android app, in which the user uploads a photo. Now, I am calling a method from the server, which will return me a list of users. I would like to display this list along with the photos. The images stored in the server are in byte-array. So I am converting them to String and then to Bitmap for showing. Unfortunately, it is not working as I am doing stuff with a Adapters as well. The image retrieved in adapter class is null. What am I doing wrong?

OtherUsers.java :

public class OtherUsers extends Activity {

    private PersonServiceImpl personService = new PersonServiceImpl();

    private static volatile List<RestPerson> restPersonList = new ArrayList<>();

    public static final String firstName = "firstname";
    public static final String userImage = "userimage";

    static final Long userId = (long)0;
    ListView listView;
    UserAdapter userAdapter;

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

        restPersonList = this.personService.getOtherUsers();
       // Base64 base64Encoder = new Base64();

        ArrayList<HashMap<String, String>> usersArrayHashList = new ArrayList<>();
        for(RestPerson restPerson : restPersonList){
            HashMap<String, String> restDisplay = new HashMap<>();
            restDisplay.put("userId",String.valueOf(restPerson.getUserId()));
            restDisplay.put("firstName",restPerson.getFirstName());

           restDisplay.put("userImage","data:image/png;base64," + Base64.encode(restPerson.getProfilePhoto()));
            usersArrayHashList.add(restDisplay);
        }

        listView = (ListView) findViewById(R.id.usersdisplaylist);

        userAdapter = new UserAdapter(this,usersArrayHashList);

        listView.setAdapter(userAdapter);

        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                                    int position, long id) {
                Long userid = restPersonList.get(position).getUserId();
                Log.d("Userid is ", String.valueOf(userid));
            }

        });

UserAdapter class :

public class UserAdapter extends BaseAdapter {

    private Activity activity;
    private ArrayList<HashMap<String, String>> data;
    private static LayoutInflater inflater = null;

    public UserAdapter(Activity a, ArrayList<HashMap<String, String>> d) {
        activity = a;
        data = d;
        inflater = (LayoutInflater) activity.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }


    @Override
    public int getCount() {
        return data.size();
    }

    @Override
    public Object getItem(int position) {
        return position;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        View view = convertView;
        if (convertView == null)
            view = inflater.inflate(R.layout.userprofiles, null);

        TextView username = (TextView) view.findViewById(R.id.userName);
        ImageView userImage = (ImageView) view.findViewById(R.id.userImage);
        HashMap<String, String> usersList = new HashMap<>();
        usersList = data.get(position);
       username.setText(usersList.get(OtherUsers.firstName));
        String image = usersList.get(OtherUsers.userImage);
        Log.d("Image is ",image);
        byte[] newImageBytes = image.getBytes();
        Bitmap bitmap = BitmapFactory.decodeByteArray(newImageBytes,0,newImageBytes.length);
        userImage.setImageBitmap(bitmap);
        userImage.setImageBitmap(null);
        return view;
    }
}

If there is any other information required, kindly let me know. Thanks.

Update Sorry, forgot to put LogCat

08-24 13:43:16.618  29948-29948/internetlegion.com.gradlecheck E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: internetlegion.com.gradlecheck, PID: 29948
    java.lang.NullPointerException: println needs a message
            at android.util.Log.println_native(Native Method)
            at android.util.Log.d(Log.java:139)
            at internetlegion.com.gradlecheck.Adapters.UserAdapter.getView(UserAdapter.java:62)
            at android.widget.AbsListView.obtainView(AbsListView.java:2347)
            at android.widget.ListView.measureHeightOfChildren(ListView.java:1270)
            at android.widget.ListView.onMeasure(ListView.java:1182)
            at android.view.View.measure(View.java:17547)

Answer 1

data struct that you have used in adapter is very strange. it's better to create one class with three property and send one list of those to adapter class. any way, your problem is :

public static final String userImage = "userimage";

you define userImage with value userimage, then you insert into hashmap with "userImage" that is not equal with value of userImage ( value have lower case i) then you have try to get "userimage" from hashmap that is not exists, so value is null.

Answer:

you can change following line:

restDisplay.put("userImage","data:image/png;base64," + Base64.encode(restPerson.getProfilePhoto()));

to

restDisplay.put(userImage,"data:image/png;base64," + Base64.encode(restPerson.getProfilePhoto()));

but better way is create custom object.