错误单击按钮上单击Android的方法

Question

i read Could not find a method onClick(View) in the activity and java.lang.IllegalStateException: Could not find a method onClick(View) but still cant solve this..

I just try to learning Android, and i try to refreshing a list with a button click..

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <Button
            android:id="@+id/OnlineShopping"
            android:layout_width="0dip"
            android:layout_height="wrap_content"
            android:layout_weight=".3"
            android:text="@string/onlineShopping"
            android:textSize="10sp" />

        <Button
            android:id="@+id/MyAccount"
            android:layout_width="0dip"
            android:layout_height="wrap_content"
            android:layout_weight=".3"
            android:text="@string/myAccount"
            android:textSize="10sp" />

        <Button
            android:id="@+id/CheckIn"
            android:layout_width="0dip"
            android:layout_height="wrap_content"
            android:layout_weight=".3"
            android:onClick="refresh"
            android:text="@string/checkIn"
            android:textSize="10sp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="fill_parent"
        android:layout_height="0dip"
        android:layout_weight="0.45"
        android:orientation="vertical" >

        <TextView
            android:id="@+id/PlacesListLabel"
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:paddingLeft="3sp"
            android:text="@string/retrievingPlaces" />

        <ListView
            android:id="@+id/PlacesList"
            android:layout_width="fill_parent"
            android:layout_height="0dip"
            android:layout_weight="1" />
    </LinearLayout>

</LinearLayout>

MainActivity.java

public class MainActivity extends Activity {

  private ListView placesList;
  private List<Place> places = null;


  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    placesList = (ListView) findViewById(R.id.PlacesList);

    new CheckInTask().execute();

    // start retrieving the list of nearby places
    new ListOfPlacesAsyncRetriever().execute();

    placesList.setOnItemClickListener(placesListClickListener);
  }


  /**
   * AsyncTask for calling Mobile Assistant API for checking into a 
   * place (e.g., a store).
   */
  private class CheckInTask extends AsyncTask<Void, Void, Void> {

    /**
     * Calls appropriate CloudEndpoint to indicate that user checked into a place.
     *
     * @param params the place where the user is checking in.
     */
    @Override
    protected Void doInBackground(Void... params) {
      CheckIn checkin = new com.mobileshopping.checkinendpoint.model.CheckIn();

      // Set the ID of the store where the user is.
      checkin.setPlaceId("StoreNo123");

      Checkinendpoint.Builder builder = new Checkinendpoint.Builder(
          AndroidHttp.newCompatibleTransport(), new JacksonFactory(), null);

      builder = CloudEndpointUtils.updateBuilder(builder);

      Checkinendpoint endpoint = builder.build();


      try {
        endpoint.insertCheckIn(checkin).execute();
      } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }

      return null;
    }
  }


  /**
   * AsyncTask for retrieving the list of places (e.g., stores) and updating the
   * corresponding results list.
   */
  private class ListOfPlacesAsyncRetriever extends AsyncTask<Void, Void, CollectionResponsePlace> {

    @Override
    protected CollectionResponsePlace doInBackground(Void... params) {


      Placeendpoint.Builder endpointBuilder = new Placeendpoint.Builder(
          AndroidHttp.newCompatibleTransport(), new JacksonFactory(), null);

      endpointBuilder = CloudEndpointUtils.updateBuilder(endpointBuilder);


      CollectionResponsePlace result;

      Placeendpoint endpoint = endpointBuilder.build();

      try {
        result = endpoint.listPlace().execute();
      } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
        result = null;
      }
      return result;
    }

    @Override
    @SuppressWarnings("null")
    protected void onPostExecute(CollectionResponsePlace result) {
      ListAdapter placesListAdapter = createPlaceListAdapter(result.getItems());
      placesList.setAdapter(placesListAdapter);

      places = result.getItems();
    }

    public void refresh(View test){

    }

    private ListAdapter createPlaceListAdapter(List<Place> places) {
      final double kilometersInAMile = 1.60934;
      List<Map<String, Object>> data = new ArrayList<Map<String, Object>>();
      for (Place place : places) {
        Map<String, Object> map = new HashMap<String, Object>();
        map.put("placeIcon", R.drawable.ic_launcher);
        map.put("placeName", place.getName());
        map.put("placeAddress", place.getAddress());
        String distance = "1.2";
        map.put("placeDistance", distance);
        data.add(map);
      }

      SimpleAdapter adapter = new SimpleAdapter(MainActivity.this, data, R.layout.place_item,
          new String[] {"placeIcon", "placeName", "placeAddress", "placeDistance"},
          new int[] {R.id.place_Icon, R.id.place_name, R.id.place_address, R.id.place_distance});

      return adapter;
    }

  }

  private OnItemClickListener placesListClickListener = new OnItemClickListener() {
    @Override
    public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
      Place selectedPlace = places.get((int) arg3);

      new CheckInTask().execute();

      PlaceDetailsActivity.currentPlace = selectedPlace;
      Intent i = new Intent(MainActivity.this, PlaceDetailsActivity.class);
      startActivity(i);
      }
  };  


}

from that activity_main.xml i try to call function refresh on Activity class.. but from logcat i got this :

 03-18 03:51:43.615: E/AndroidRuntime(759): 
 java.lang.IllegalStateException: Could not find a method refresh(View) 
 in the activity class com.mobileshopping.MainActivity 
 for onClick handler on view class android.widget.Button with id 'CheckIn'

Do i need to register somewhere else or i have some missing code??

Answer 1

You have the refresh(View) method inside of your ListOfPlacesAsyncRetriever class, instead of directly inside of your MainActivity class. Move it outside of that and you should be good.

Answer 2

You have placed the refresh() method inside the Asynctask that's why the system can't find the method. But it should be a method of MainActivity class.

Now, place your refresh() method outside the AsyncTask as below...

public class MainActivity extends Activity {

    private ListView placesList;
    private List<Place> places = null;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        placesList = (ListView) findViewById(R.id.PlacesList);

        new CheckInTask().execute();

        // start retrieving the list of nearby places
        new ListOfPlacesAsyncRetriever().execute();

        placesList.setOnItemClickListener(placesListClickListener);

    }

    public void refresh(View test){

    }


   .............

   ...........
}