I have an app that shows images from an tumblr account. At the bottom of the list there is a "load more" button, when pressed loads 20 more images to the list. As it works now the app only appends to the new images to the list, so there is shown 40 images after the button has been pressed. How can i make it so the list only contains the new 20 images?
My code looks like this:
public class Example extends Activity {
static ArrayList<Tumblr> tumblrs;
Context context = null;
ListView listView = null;
TextView footer;
int offset = 0;
ProgressDialog pDialog;
public boolean isNew = false;
private String searchUrl = "http://api.tumblr.com/v2/blog/factsandchicks.com/posts?api_key=API_KEY&offset=0";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
try {
tumblrs = getTumblrs();
listView = (ListView) findViewById(R.id.list);
View v = getLayoutInflater().inflate(R.layout.footer_layout, null);
footer = (TextView) v.findViewById(R.id.tvFoot);
listView.addFooterView(v);
listView.setAdapter(new UserItemAdapter(this, R.layout.listitem));
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (JSONException e) {
e.printStackTrace();
}
footer.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
new loadMoreListView().execute();
}
});
}
public class UserItemAdapter extends ArrayAdapter<Tumblr> {
public UserItemAdapter(Context context, int imageViewResourceId) {
super(context, imageViewResourceId, tumblrs);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View v = convertView;
if (v == null) {
LayoutInflater vi = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
v = vi.inflate(R.layout.listitem, null);
}
Tumblr tumblr = tumblrs.get(position);
if (tumblr != null) {
ImageView image = (ImageView) v.findViewById(R.id.avatar);
if (image != null) {
image.setImageBitmap(getBitmap(tumblr.image_url));
}
}
return v;
}
}
public Bitmap getBitmap(String bitmapUrl) {
try {
URL url = new URL(bitmapUrl);
return BitmapFactory.decodeStream(url.openConnection()
.getInputStream());
} catch (Exception ex) {
return null;
}
}
public ArrayList<Tumblr> getTumblrs() throws ClientProtocolException,
IOException, JSONException {
searchUrl = "http://api.tumblr.com/v2/blog/factsandchicks.com/posts?api_key=API_KEY&offset=0";
ArrayList<Tumblr> tumblrs = new ArrayList<Tumblr>();
HttpClient client = new DefaultHttpClient();
HttpGet get = new HttpGet(searchUrl);
ResponseHandler<String> responseHandler = new BasicResponseHandler();
String responseBody = null;
try {
responseBody = client.execute(get, responseHandler);
} catch (Exception ex) {
ex.printStackTrace();
}
JSONObject jsonObject = new JSONObject(responseBody);
JSONArray posts = jsonObject.getJSONObject("response").getJSONArray(
"posts");
for (int i = 0; i < posts.length(); i++) {
JSONArray photos = posts.getJSONObject(i).getJSONArray("photos");
for (int j = 0; j < photos.length(); j++) {
JSONObject photo = photos.getJSONObject(j);
String url = photo.getJSONArray("alt_sizes").getJSONObject(0)
.getString("url");
Tumblr tumblr = new Tumblr(url);
tumblrs.add(tumblr);
}
}
return tumblrs;
}
public class Tumblr {
public String image_url;
public Tumblr(String url) {
this.image_url = url;
}
}
private class loadMoreListView extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
// Showing progress dialog before sending http request
pDialog = new ProgressDialog(Example.this);
pDialog.setMessage("Please wait..");
pDialog.setIndeterminate(true);
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... unused) {
// TODO Auto-generated method stub
runOnUiThread(new Runnable() {
public void run() {
// increment current page
offset += 2;
// Next page request
searchUrl = "http://api.tumblr.com/v2/blog/factsandchicks.com/posts?api_key=API_KEY&offset="
+ offset;
HttpClient client = new DefaultHttpClient();
HttpGet get = new HttpGet(searchUrl);
ResponseHandler<String> responseHandler = new BasicResponseHandler();
String responseBody = null;
try {
responseBody = client.execute(get, responseHandler);
} catch (Exception ex) {
ex.printStackTrace();
}
JSONObject jsonObject;
try {
jsonObject = new JSONObject(responseBody);
JSONArray posts = jsonObject.getJSONObject("response")
.getJSONArray("posts");
for (int i = 0; i < posts.length(); i++) {
JSONArray photos = posts.getJSONObject(i)
.getJSONArray("photos");
for (int j = 0; j < photos.length(); j++) {
JSONObject photo = photos.getJSONObject(j);
String url = photo.getJSONArray("alt_sizes")
.getJSONObject(0).getString("url");
Tumblr tumblr = new Tumblr(url);
tumblrs.add(tumblr);
}
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
// get listview current position - used to maintain scroll
// position
int currentPosition = listView.getFirstVisiblePosition();
// Setting new scroll position
listView.setSelectionFromTop(currentPosition + 1, 0);
}
});
return null;
}
protected void onPostExecute(Void unused) {
pDialog.dismiss();
}
}
}
Any help is appriciated.