我有4个返回null的微调器，我无法弄清楚原因。我确保我有正确的ID，并遵循我在另一个活动中使用的代码，以确保它是正确的，但它一直在崩溃说
01-25 17:02:47.464: E/AndroidRuntime(13052): java.lang.NullPointerException
01-25 17:02:47.464: E/AndroidRuntime(13052): at com.skateconnect.AllSpotsActivity$2.onClick(AllSpotsActivity.java:157)
该类的整个代码是
public class AllSpotsActivity extends ListActivity {
// Progress Dialog
private ProgressDialog pDialog;
// Creating JSON Parser object
JSONParser jParser = new JSONParser();
ArrayList<HashMap<String, String>> spotsList;
GPSTracker gps;
// url to get all products list
//private static String url_all = "http://72.83.78.137:8080/skate_connect/get_all.php";
private static String url_all = "http://skateconnect.no-ip.biz:8080/skate_connect/get_all.php";
// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_SPOTS = "spots";
private static final String TAG_PID = "pid";
private static final String TAG_NAME = "name";
private int search_trig=0;
// products JSONArray
JSONArray spots = null;
private Spinner spinner_pavement, spinner_traffic, spinner_enviro,spinner_dist;
private String str_pavement, str_traffic, str_enviro,str_dist;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.all_spots);
gps = new GPSTracker(AllSpotsActivity.this);
// Hashmap for ListView
spotsList = new ArrayList<HashMap<String, String>>();
// Loading products in Background Thread
whattosearch();
//new LoadAllSpots().execute();
// Get listview
ListView lv = getListView();
// on seleting single product
// launching Edit Product Screen
lv.setOnItemClickListener(new OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view,
int position, long id) {
// getting values from selected ListItem
String pid = ((TextView) view.findViewById(R.id.pid)).getText()
.toString();
// Starting new intent
Intent in = new Intent(getApplicationContext(),
ViewSpotActivity.class);
// sending pid to next activity
in.putExtra(TAG_PID, pid);
// starting new activity and expecting some response back
startActivityForResult(in, 100);
}
});
}
public class CustomOnItemSelectedListener implements OnItemSelectedListener {
@Override
public void onItemSelected(AdapterView<?> parent, View view, int pos,
long id) {
Toast.makeText(parent.getContext(),
parent.getItemAtPosition(pos).toString(),
Toast.LENGTH_SHORT).show();
}
@Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
}
}
public void addListenerOnSpinnerItemSelection() {
spinner_pavement = (Spinner) findViewById(R.id.spinner_search_pavement);
spinner_pavement
.setOnItemSelectedListener(new CustomOnItemSelectedListener());
spinner_traffic = (Spinner) findViewById(R.id.spinner_search_traffic);
spinner_traffic
.setOnItemSelectedListener(new CustomOnItemSelectedListener());
spinner_enviro = (Spinner) findViewById(R.id.spinner_search_enviro);
spinner_enviro
.setOnItemSelectedListener(new CustomOnItemSelectedListener());
spinner_dist = (Spinner) findViewById(R.id.spinner_dist);
spinner_dist
.setOnItemSelectedListener(new CustomOnItemSelectedListener());
}
void whattosearch(){
final Dialog search = new Dialog(this);
search.setContentView(R.layout.search);
search.setTitle("What to Search For: ");
search.setCancelable(false);
spinner_pavement = (Spinner) findViewById(R.id.spinner_search_pavement);
spinner_traffic = (Spinner) findViewById(R.id.spinner_search_traffic);
spinner_enviro = (Spinner) findViewById(R.id.spinner_search_enviro);
spinner_dist = (Spinner) findViewById(R.id.spinner_dist);
Button dialogButton = (Button) search.findViewById(R.id.ButtonOK);
// if button is clicked, close the custom dialog
dialogButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//these are returning null...
str_pavement = spinner_pavement.getSelectedItem().toString();
str_traffic = spinner_traffic.getSelectedItem().toString();
str_enviro = spinner_enviro.getSelectedItem().toString();
str_dist = spinner_dist.getSelectedItem().toString();
search_trig=1;
search.dismiss();
new LoadAllSpots().execute();
}
});
Button dialogSeeAll = (Button) search.findViewById(R.id.ButtonAll);
// if button is clicked, close the custom dialog
dialogSeeAll.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
search.dismiss();
search_trig=0;
new LoadAllSpots().execute();
}
});
search.show();
}
// Response from Edit Product Activity
// using longest equation to get least amount of error
@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 product
// reload this screen again
Intent intent = getIntent();
finish();
startActivity(intent);
}
}
private double getDistance(double fromLat, double fromLon, double toLat,
double toLon) {
Location location1 = new Location("loc1");
location1.setLatitude(fromLat);
location1.setLongitude(fromLon);
Location location2 = new Location("loc2");
location2.setLatitude(toLat);
location2.setLongitude(toLon);
double d = location1.distanceTo(location2) * 0.000621371;// convert to
// miles
return d;
}
/**
* Background Async Task to Load all product by making HTTP Request
* */
class LoadAllSpots extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(AllSpotsActivity.this);
pDialog.setMessage("Loading Spots. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting All products from url
* */
@Override
protected String doInBackground(String... args) {
double slat = gps.getLatitude();
double slong = gps.getLongitude();
// Building Parameters
List<NameValuePair> params = new ArrayList<NameValuePair>();
// getting JSON string from URL
JSONObject json = jParser.makeHttpRequest(url_all, "GET", params);
// Check your log cat for JSON reponse
Log.d("All Spots: ", json.toString());
try {
// Checking for SUCCESS TAG
int success = json.getInt(TAG_SUCCESS);
if (success == 1) {
// products found
// Getting Array of Products
spots = json.getJSONArray(TAG_SPOTS);
// looping through All Products
for (int i = 0; i < spots.length(); i++) {
JSONObject c = spots.getJSONObject(i);
// Storing each json item in variable
double elong = Double.parseDouble(c
.getString("longitude"));
double elat = Double.parseDouble(c
.getString("latitude"));
double dist = getDistance(slat, slong, elat, elong);
String distance = String.format("%.1f", dist);
String id = c.getString(TAG_PID);
String pave = c.getString("pavement");
String traffic = c.getString("traffic");
String enviro = c.getString("environment");
String name = c.getString(TAG_NAME) + ": " + distance
+ " Miles Away";
//need to create case statement here on search_trig
//0 means search all
//1 means search by inputs
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
// adding each child node to HashMap key => value
map.put(TAG_PID, id);
map.put(TAG_NAME, name);
map.put("distance", distance);
// adding HashList to ArrayList
spotsList.add(map);
}
} else {
// no products found
// Launch Add New product Activity
Intent i = new Intent(getApplicationContext(),
NewSpotActivity.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 products
pDialog.dismiss();
// updating UI from Background Thread
runOnUiThread(new Runnable() {
@Override
public void run() {
/**
* Updating parsed JSON data into ListView
* */
ListAdapter adapter = new SimpleAdapter(
AllSpotsActivity.this, spotsList,
R.layout.list_item, new String[] { TAG_PID,
TAG_NAME, "distance" }, new int[] {
R.id.pid, R.id.name, R.id.distance });
Collections.sort(spotsList,
new Comparator<Map<String, String>>() {
@Override
public int compare(Map<String, String> o1,
Map<String, String> o2) {
String value1 = o1.get("distance");
String value2 = o2.get("distance");
return Double.valueOf(value1).compareTo(
Double.valueOf(value2));
}
});
// updating listview
setListAdapter(adapter);
}
});
}
}
}
如果有人能帮助我，或指出我的方向是正确的，那就太好了。我想这可能是因为微调器在对话框中，但我不太确定。
提前谢谢你，
泰勒
编辑：完整的logcat
01-25 20:21:03.652: E/AndroidRuntime(18730): FATAL EXCEPTION: main
01-25 20:21:03.652: E/AndroidRuntime(18730): Process: com.skateconnect, PID: 18730
01-25 20:21:03.652: E/AndroidRuntime(18730): java.lang.NullPointerException
01-25 20:21:03.652: E/AndroidRuntime(18730): at com.skateconnect.AllSpotsActivity$2.onClick(AllSpotsActivity.java:157)
01-25 20:21:03.652: E/AndroidRuntime(18730): at android.view.View.performClick(View.java:4452)
01-25 20:21:03.652: E/AndroidRuntime(18730): at android.view.View$PerformClick.run(View.java:18498)
01-25 20:21:03.652: E/AndroidRuntime(18730): at android.os.Handler.handleCallback(Handler.java:733)
01-25 20:21:03.652: E/AndroidRuntime(18730): at android.os.Handler.dispatchMessage(Handler.java:95)
01-25 20:21:03.652: E/AndroidRuntime(18730): at android.os.Looper.loop(Looper.java:137)
01-25 20:21:03.652: E/AndroidRuntime(18730): at android.app.ActivityThread.main(ActivityThread.java:5083)
01-25 20:21:03.652: E/AndroidRuntime(18730): at java.lang.reflect.Method.invokeNative(Native Method)
01-25 20:21:03.652: E/AndroidRuntime(18730): at java.lang.reflect.Method.invoke(Method.java:515)
01-25 20:21:03.652: E/AndroidRuntime(18730): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
01-25 20:21:03.652: E/AndroidRuntime(18730): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
01-25 20:21:03.652: E/AndroidRuntime(18730): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：1)
更改whattosearch（）方法中的以下行...
spinner_pavement = (Spinner) findViewById(R.id.spinner_search_pavement);
spinner_traffic = (Spinner) findViewById(R.id.spinner_search_traffic);
spinner_enviro = (Spinner) findViewById(R.id.spinner_search_enviro);
spinner_dist = (Spinner) findViewById(R.id.spinner_dist);
...使用findViewById(...)的{{1}}方法。实施例...
Dialog您似乎已经将电线穿过，并且您试图在活动的内容视图中找到旋转器而不是在对话框中。
答案 1 :(得分：0)
我会尝试在您创建getApplicationContext()的{{1}}方法中使用parent.getContext()代替onItemSelected()。