我不确定为什么我会收到此类强制转换异常。我做了[项目 - ＆gt;清洁]几次，仍然没有工作。
有人请帮帮我。
谢谢。
这是ScheduleFragment.java
public class ScheduleFragment extends Fragment {
public static final String PREFS_NAME="PreferencesValue";
public ProgressDialog pDialog;
private ListView myListView;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> subjectList;
// url to get all subjects list
private static String url_all_subjects = "http://192.168.1.12/android_project/get_subjects.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_STUDENT = "student";
private static final String TAG_MATRIX_ID = "matrix_id";
private static final String TAG_NAME = "name";
// subject JSONArray
JSONArray student = null;
public ScheduleFragment(){}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
{
View rootView = inflater.inflate(R.layout.fragment_schedule, container, false);
//Bring the value from login page
TextView tvmatrix = (TextView)rootView.findViewById(R.id.textViewMatrix);
SharedPreferences settings = getActivity().getSharedPreferences(PREFS_NAME, 0);
tvmatrix.setText(settings.getString("matrix", "A13123"));
//-------------------------------------------------------------------------
//------------------------------------CREATING A LISTVIEW-----------------------
// Loading subject in Background Thread
new LoadAllSubject().execute();
// Hashmap for ListView
subjectList = new ArrayList<HashMap<String, String>>();
myListView = (ListView) rootView.findViewById(R.id.textViewMatrix);
// on selecting single subject
myListView.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String matrix_id = ((TextView) view.findViewById(R.id.textViewMatrix)).getText()
.toString();
// Starting new intent
Intent in = new Intent(getActivity().getApplicationContext(),
SingleSubject.class);
// sending matrix id to next activity
in.putExtra(TAG_MATRIX_ID, matrix_id);
// starting new activity and expecting some response back
startActivityForResult(in, 100);
}
});
return rootView;
}
/**
* Background Async Task to Load all product by making HTTP Request
* */
class LoadAllSubject extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = ProgressDialog.show(ScheduleFragment.this.getActivity(), "Progress", "Loading subjects. Please wait...", false);
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
}
/**
* getting All products from url
* */
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_subjects, "GET", params);
// Check your log cat for JSON reponse
Log.d("All Subjects: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// subject found
// Getting Array of Subject
student = json.getJSONArray(TAG_STUDENT);
// looping through All Subjects
for (int i = 0; i < student.length(); i++) {
JSONObject c = student.getJSONObject(i);
// Storing each json item in variable
String matrix_id = c.getString(TAG_MATRIX_ID);
String name = c.getString(TAG_NAME);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_MATRIX_ID, matrix_id);
map.put(TAG_NAME, name);
// adding HashList to ArrayList
subjectList.add(map);
}
} else {
// no subjects found
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
super.onPostExecute(file_url);
// dismiss the dialog after getting all products
pDialog.dismiss();
// updating UI from Background Thread
ListAdapter adapter = new SimpleAdapter(
getActivity(), subjectList,
R.layout.all_subject, new String[] { TAG_MATRIX_ID,
TAG_NAME},
new int[] { R.id.matrix_id, R.id.name });
// updating listview
myListView.setAdapter(adapter);
}
}
}
这是all_subject.xml
<TextView
android:id="@+id/matrix_id"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:visibility="gone" />
<!-- Name Label -->
<TextView
android:id="@+id/name"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:paddingTop="6dip"
android:paddingLeft="6dip"
android:textSize="17dip"
android:textStyle="bold" />
这是fragment_schedule.xml
<ListView
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
<TextView
android:id="@+id/textViewMatrix"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="66dp"
android:text="Large Text"
android:textAppearance="?android:attr/textAppearanceLarge" />
这是错误日志。
03-25 12:14:06.177: W/dalvikvm(1129): threadid=1: thread exiting with uncaught exception (group=0x40d09930)
03-25 12:14:06.271: E/AndroidRuntime(1129): FATAL EXCEPTION: main
03-25 12:14:06.271: E/AndroidRuntime(1129): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.ultra.esc/com.ultra.esc.HomeActivity}: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.ListView
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.app.ActivityThread.access$600(ActivityThread.java:141)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.os.Handler.dispatchMessage(Handler.java:99)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.os.Looper.loop(Looper.java:137)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.app.ActivityThread.main(ActivityThread.java:5039)
03-25 12:14:06.271: E/AndroidRuntime(1129): at java.lang.reflect.Method.invokeNative(Native Method)
03-25 12:14:06.271: E/AndroidRuntime(1129): at java.lang.reflect.Method.invoke(Method.java:511)
03-25 12:14:06.271: E/AndroidRuntime(1129): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
03-25 12:14:06.271: E/AndroidRuntime(1129): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
03-25 12:14:06.271: E/AndroidRuntime(1129): at dalvik.system.NativeStart.main(Native Method)
03-25 12:14:06.271: E/AndroidRuntime(1129): Caused by: java.lang.ClassCastException: android.widget.TextView cannot be cast to android.widget.ListView
03-25 12:14:06.271: E/AndroidRuntime(1129): at com.ultra.esc.ScheduleFragment.onCreateView(ScheduleFragment.java:88)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.app.Fragment.performCreateView(Fragment.java:1695)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:885)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1057)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.app.BackStackRecord.run(BackStackRecord.java:682)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1435)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.app.Activity.performStart(Activity.java:5113)
03-25 12:14:06.271: E/AndroidRuntime(1129): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2153)
03-25 12:14:06.271: E/AndroidRuntime(1129): ... 11 more
答案 0 :(得分：2)
你错了吗
myListView = (ListView) rootView.findViewById(R.id.textViewMatrix);
textViewMatrix TextView ID不是ListView ID，也会发布您的fragment_schedule.xml文件
并改变这个
<ListView
android:id="@android:id/list" ...../>
到
<ListView
android:id="@+id/list"
.......
......../>
在你的片段中使用
myListView = (ListView) rootView.findViewById(R.id.list);
答案 1 :(得分：1)
你有这个
myListView = (ListView) rootView.findViewById(R.id.textViewMatrix);
可能ID textViewMatrix是TextView。
您已使用相同的ID
初始化textview，确认了这一点TextView tvmatrix = (TextView)rootView.findViewById(R.id.textViewMatrix);
// see the id textViewMatrix its a textview and you use the same to initialize listview
您的ListView
fragment_schedule.xml
<ListView
android:id="@+id/listView1
然后
myListView = (ListView) rootView.findViewById(R.id.listView1);
编辑：
更改此
<ListView
android:id="@android:id/list"
// you would use this id when you extend ListFragment and inflate a custom layout fro the fragment.
到
<ListView
android:id="@+id/list"
然后
myListView = (ListView) rootView.findViewById(R.id.list);