当我在行中执行用于过滤的java.lang.NullPointerException代码时出现错误 ( )ListViewEditText
AllSuggestionsActivity.this.adapter.getFilter().filter(cs);
请帮助。
public class AllSuggestionsActivity extends ListActivity {
EditText inputSearch;
ListView lstList;
// Progress Dialog
private ProgressDialog pDialog;
ArrayAdapter<String> adapter = null;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> suggestionsList;
// url to get all suggestions list
private static String url_all_suggestions = "http://10.0.2.2/JKUAT-M-SUGGESTION-BOX/get_all_suggestions.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_SUGGESTIONS = "suggestions";
private static final String TAG_SID = "sid";
private static final String TAG_SUBJECT = "subject";
// suggestions JSONArray
JSONArray suggestions = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_suggestions);
inputSearch = (EditText) findViewById(R.id.inputSearch);
lstList = (ListView) findViewById(android.R.id.list);
// Hashmap for ListView
suggestionsList = new ArrayList<HashMap<String, String>>();
// Loading suggestions in Background Thread
new LoadAllSuggestions().execute();
// Get listview
ListView lv = getListView();
/**
* Enabling Search Filter
* */
inputSearch.addTextChangedListener(new TextWatcher() {
@Override
public void onTextChanged(CharSequence cs, int arg1, int arg2, int arg3) {
// When user changed the Text
AllSuggestionsActivity.this.adapter.getFilter().filter(cs);
}
@Override
public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,
int arg3) {
// TODO Auto-generated method stub
}
@Override
public void afterTextChanged(Editable arg0) {
// TODO Auto-generated method stub
}
});
// on seleting single suggestion
// launching Edit Suggestion Screen
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String sid = ((TextView) view.findViewById(R.id.sid)).getText()
.toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(),
EditSuggestionActivity.class);
// sending sid to next activity
in.putExtra(TAG_SID, sid);
// starting new activity and expecting some response back
startActivityForResult(in, 100);
}
});
}
// Response from Edit Suggestion Activity
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
// if result code 100
if (resultCode == 100) {
// if result code 100 is received
// means user edited/deleted suggestion
// reload this screen again
Intent intent = getIntent();
finish();
startActivity(intent);
}
}
/**
* Background Async Task to Load all suggestion by making HTTP Request
* */
class LoadAllSuggestions extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(AllSuggestionsActivity.this);
pDialog.setMessage("Loading all suggestions. Please wait.......");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting All suggestions from url
* */
@Override
protected String doInBackground(String... args) {
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all_suggestions,
"GET", params);
// Check your log cat for JSON reponse
Log.d("All Suggestions: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// suggestions found
// Getting Array of Suggestions
suggestions = json.getJSONArray(TAG_SUGGESTIONS);
// looping through All Suggestions
for (int i = 0; i < suggestions.length(); i++) {
JSONObject c = suggestions.getJSONObject(i);
// Storing each json item in variable
String id = c.getString(TAG_SID);
String subject = c.getString(TAG_SUBJECT);
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_SID, id);
map.put(TAG_SUBJECT, subject);
// adding HashList to ArrayList
suggestionsList.add(map);
}
} else {
// no suggestions found
Intent i = new Intent(getApplicationContext(),
MainScreenActivity.class);
// Closing all previous activities
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
}
} catch (JSONException e) {
e.printStackTrace();
}
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
@Override
protected void onPostExecute(String file_url) {
// dismiss the dialog after getting all suggestions
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
@Override
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
AllSuggestionsActivity.this, suggestionsList,
R.layout.list_item, new String[] { TAG_SID,
TAG_SUBJECT }, new int[] { R.id.sid,
R.id.subject });
// updating listview
setListAdapter(adapter);
}
});
}
}
}
列表视图的 xml 代码：
<?xml version="1.0" encoding="utf-8"?>
<ScrollView
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:fillViewport="true">
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical">
<EditText
android:id="@+id/inputSearch"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:ems="10"
android:maxLines="1"
android:hint="Search" >
<requestFocus />
</EditText>-->
<!-- Main ListView
Always give id value as list(@android:id/list)
-->
<ListView
android:id="@android:id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
</LinearLayout>
enter code here
</ScrollView>