tumblrアカウントの画像を表示するアプリがあります。リストの下部にある[さらに読み込む]ボタンを押すと、さらに20枚の画像がリストに読み込まれます。現在は機能しているため、アプリはリストの新しい画像にのみ追加するため、ボタンを押した後に40枚の画像が表示されます。リストに新しい20枚の画像のみが含まれるようにするにはどうすればよいですか？
私のコードは次のようになります。
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();
}
}
}
どんな助けでも適用されます。