本文介绍了片段中使用 SimpleAdapter 的简单列表视图的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
这是我的片段扩展 ListFragment 代码，下面是它显示的错误.几乎相同的代码对活动工作正常，除了在活动中我通过
Here is my code for fragment extending ListFragment and below are the errors it is showing.Almost Same code is working fine for activity except that in activity i am getting listview through
ListView lv = getListView();
并在片段中通过
lv= (ListView)rootView.findViewById(R.id.list);
它在 java:109 行显示空指针异常 lv.setOnItemClickListener(new AdapterView.OnItemClickListener()如果我删除 setOnItemClickListener 它会在 lv.setAdapter(adapter); 上显示空指针异常SoundCloudFragment.java
It shows nullpointer exception on line java:109 lv.setOnItemClickListener(new AdapterView.OnItemClickListener()If i remove setOnItemClickListener it shows null pointer exception on lv.setAdapter(adapter);SoundCloudFragment.java
public class SoundCloudFragment extends ListFragment {
private ProgressDialog pDialog;
private FragmentActivity myContext;
ListView lv;
@Override
public void onAttach(Activity activity) {
if (activity instanceof FragmentActivity) {
myContext = (FragmentActivity) activity;
}
super.onAttach(activity);
}
// contacts JSONArray
JSONArray contacts = null;
// Hashmap for ListView
ArrayList<HashMap<String, String>> contactList;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// mVisulizerView = (VisualizerView)findViewById(R.id.visualizerView);
View rootView = inflater.inflate(R.layout.soundcloud, container, false);
lv= (ListView)rootView.findViewById(R.id.list);
// Get ListView object from xml
// lv = getListView();
lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id)
{
// getting values from selected ListItem
String name = ((TextView) view.findViewById(R.id.name)).getText().toString();
String cost = ((TextView) view.findViewById(R.id.email)).getText().toString();
String description = ((TextView) view.findViewById(R.id.mobile)).getText().toString();
// Starting single contact activity
Intent in = new Intent(myContext,
SingleContactActivity.class);
in.putExtra("name", TAG_TITLE);
in.putExtra("id", cost);
startActivity(in);
}
});
// Calling async task to get json
new GetContacts().execute();
return rootView;
}
private class GetContacts extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Showing progress dialog
pDialog = new ProgressDialog(myContext);
pDialog.setMessage("Please wait...");
pDialog.setCancelable(false);
pDialog.show();
}
@Override
protected Void doInBackground(Void... arg0) {
// Creating service handler class instance
ServiceHandler sh = new ServiceHandler();
// Making a request to url and getting response
String jsonStr = sh.makeServiceCall(url, ServiceHandler.GET);
Log.d("Response: ", "> " + jsonStr);
if (jsonStr != null) {
try {
JSONArray json = new JSONArray(jsonStr);
// looping through All Contacts
for (int i = 0; i < json.length(); i++) {
JSONObject jsonObj = json.getJSONObject(i);
//JSONObject c = contacts.getJSONObject(i);
String title = jsonObj.getString(TAG_TITLE);
String id = jsonObj.getString(TAG_ID);
String kind = jsonObj.getString(TAG_KIND);
String duration =jsonObj.getString(TAG_DURATION);
/* String gender = c.getString(TAG_GENDER);
// Phone node is JSON Object
JSONObject phone = c.getJSONObject(TAG_PHONE);
String mobile = phone.getString(TAG_PHONE_MOBILE);
String home = phone.getString(TAG_PHONE_HOME);
String office = phone.getString(TAG_PHONE_OFFICE);*/
// tmp hashmap for single contact
HashMap<String, String> contact = new HashMap<String, String>();
// adding each child node to HashMap key => value
contact.put(TAG_TITLE, title);
contact.put(TAG_ID, id);
contact.put(TAG_KIND, kind);
contact.put(TAG_DURATION, duration);
// adding contact to contact list
contactList.add(contact);
}
} catch (JSONException e)
{
e.printStackTrace();
}
} else {
Log.e("ServiceHandler", "Couldn't get any data from the url");
}
return null;
}
@Override
protected void onPostExecute(Void result) {
super.onPostExecute(result);
// Dismiss the progress dialog
if (pDialog.isShowing())
pDialog.dismiss();
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
myContext, contactList,
R.layout.soundcloud_item, new String[] { TAG_TITLE, TAG_ID,
TAG_KIND }, new int[] { R.id.name,
R.id.email, R.id.mobile });
lv.setAdapter(adapter);
}
}
}
错误-
FATAL EXCEPTION: main
java.lang.NullPointerException
at com.peoplecloud.guggu.ui.fragment.SoundCloudFragment.onCreateView(SoundCloudFragment.java:109)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:829)
at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1035)
at android.app.BackStackRecord.run(BackStackRecord.java:635)
at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1397)
at android.app.FragmentManagerImpl$1.run(FragmentManager.java:426)
at android.os.Handler.handleCallback(Handler.java:615)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:153)
at android.app.ActivityThread.main(ActivityThread.java:5086)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
at dalvik.system.NativeStart.main(Native Method)
推荐答案
试试这个方法，希望能帮助你解决问题.
给定 ListView id 有两种方式.
There is two way to given ListView id.
1.android 预定义 id 如下:
1.android predefined id like :
XML
<ListView
android:id="@android:id/list"
活动
lv= (ListView) findViewById(android.R.id.list);
片段
lv= (ListView)rootView.findViewById(android.R.id.list);
2.Custom id like :
2.Custom id like :
XML
<ListView
android:id="@+id/list"
活动
lv= (ListView) findViewById(R.id.list);
片段
lv= (ListView)rootView.findViewById(R.id.list);
这篇关于片段中使用 SimpleAdapter 的简单列表视图的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！