我正在开发一个Android应用程序，需要从json获取数据项到ViewPager
public class GalleryUrlActivity extends Activity {
private GalleryViewPager mViewPager;
String anim_id,album_id,anim_name,anim_thumb,anim_url;
ArrayList<HashMap<String, String>> albumList;
int global_position=0;
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
albumList = new ArrayList<HashMap<String, String>>();
new AsycLove().execute();
}
class AsycLove extends AsyncTask<String, String, String>
{
ProgressDialog progressDialog;
@Override
protected void onPreExecute()
{
super.onPreExecute();
progressDialog = new ProgressDialog(GalleryUrlActivity.this);
progressDialog.setTitle("Loading");
progressDialog.setMessage("Please wait");
progressDialog.setCancelable(false);
progressDialog.setIndeterminate(true);
progressDialog.show();
}
@Override
protected String doInBackground(String... aurl)
{
try
{
HttpPost postMethod = null;
postMethod = new HttpPost("http://demo1.idevtechnolabs.com/smartecard/love.php");
BufferedReader bufferedReader = null;
HttpClient client = new DefaultHttpClient();
HttpResponse response = null;
response = client.execute(postMethod);
final int statusCode = response.getStatusLine().getStatusCode();
Log.v("Album ::","Response:::--->"+response.toString());
Log.v("Album ::","Status Code:::--->"+statusCode);
bufferedReader = new BufferedReader(new InputStreamReader(response.getEntity().getContent()));
StringBuffer stringBuffer = new StringBuffer("");
String line = "";
String LineSeparator = System.getProperty("line.separator");
while ((line = bufferedReader.readLine()) != null)
{
stringBuffer.append(line + LineSeparator);
}
bufferedReader.close();
//-------------CONVERT DATA TO JSON---------------------------------
try
{
String myjsonstring = stringBuffer.toString();
JSONArray jsonArray = new JSONArray(myjsonstring);
JSONObject jsonObj = null;
albumList.clear();
jsonObj = jsonArray.getJSONObject(0);
for(int i=0; i<jsonArray.length();i++)
{
jsonObj = jsonArray.getJSONObject(i);
anim_id = jsonObj.getString("animation_id");
album_id = jsonObj.getString("album_id");
anim_name = jsonObj.getString("animation_name");
anim_thumb= jsonObj.getString("animation_thumb");
anim_url = jsonObj.getString("animation_url");
anim_url=anim_url.replaceAll("\"","");
Log.v("Anim URL","Anim URL::"+anim_url);
Log.v("Anim Name","Anim Name::"+anim_name);
HashMap<String, String> tmp_album = new HashMap<String, String>();
tmp_album.put("anim_id", anim_id);
tmp_album.put("anim_thumb", anim_thumb);
tmp_album.put("anim_url",anim_url);
albumList.add(tmp_album);
Log.v("Animation URL Position","Animation::"+global_position+"::"+anim_url);
}
}
catch (Exception e)
{
Log.v("Home ::","Call JSON Exception in get Album in List--->"+e.toString());
e.printStackTrace();
}
}
catch (IOException e)
{
Log.v("Exception: Get get Album in List","Name-"+e.toString());
e.printStackTrace();
}
return "0";
}
@Override
protected void onPostExecute(String code)
{
Toast.makeText(getApplicationContext(), "Image URL Call Successfully", Toast.LENGTH_LONG).show();
Log.v("Album","Album List::"+albumList);
String urls[] = null;
for(int p=0;p<=albumList.size();p++)
{
urls[p]=albumList.get(p).get("anim_thumb");
}
List<String> items = new ArrayList<String>();
Collections.addAll(items, urls);
UrlPagerAdapter pagerAdapter = new UrlPagerAdapter(getApplicationContext(), items);
pagerAdapter.setOnItemChangeListener(new OnItemChangeListener()
{
@Override
public void onItemChange(int currentPosition)
{
Toast.makeText(GalleryUrlActivity.this, "Current item is " + currentPosition, Toast.LENGTH_SHORT).show();
}
});
mViewPager = (GalleryViewPager)findViewById(R.id.viewer);
mViewPager.setOffscreenPageLimit(3);
mViewPager.setAdapter(pagerAdapter);
progressDialog.dismiss();
progressDialog = null;
}
}
}
FATAL EXCEPTION: main
java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:251)
at java.util.ArrayList.get(ArrayList.java:304)
at ru.truba.touchgallery.GalleryUrlActivity$AsycLove.onPostExecute(GalleryUrlActivity.java:176)
at ru.truba.touchgallery.GalleryUrlActivity$AsycLove.onPostExecute(GalleryUrlActivity.java:1)
at android.os.AsyncTask.finish(AsyncTask.java:631)
at android.os.AsyncTask.access$600(AsyncTask.java:177)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:644)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5371)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)
任何人都可以告诉我为什么它是原因？
谢谢
答案 0 :(得分：2)
您没有初始化albumList。你刚刚宣布了一个变量。
ArrayList<HashMap<String, String>> albumList;
现在初始化它onCreate()方法。
albumList = new ArrayList<HashMap<String, String>>();
答案 1 :(得分：1)
试试这种方式，希望这会对你有帮助......
将albumList.clear();替换为
if(albumList!=null) {
albumList.clear();
}else {
albumList = new ArrayList<HashMap<String, String>>();
}
和
替换此代码：
String urls[] = null;
for(int p=0;p<=albumList.size();p++){
urls[p]=albumList.get(p).get("anim_thumb");
}
使用此代码
String urls[] = new String[albumList.size()];
for(int p=0;p<albumList.size();p++){
urls[p]=albumList.get(p).get("anim_thumb");
}
答案 2 :(得分：1)
我认为您忘记声明String数组，如
String[] urls = new String[albumList.size()];