構造函數LocationClient（MainActivity，MainActivity，MainActivity）未定義

因此，我正在關注使用Google Maps V2構建移動應用程序的Lynda.com教程，並且我正在配合您創建地圖的一部分應用程序正在尋找位置編程，而不是依靠setMyLocationEnabled(true)方法。所以，我的代碼，每次我去運行它崩潰的應用程序，並給我下面的錯誤在logcat的時候跟着一起：構造函數LocationClient（MainActivity，MainActivity，MainActivity）未定義

05-15 12:18:35.139: E/AndroidRuntime(22270): FATAL EXCEPTION: main 
05-15 12:18:35.139: E/AndroidRuntime(22270): Process: com.example.gmapsapp, PID: 22270 
05-15 12:18:35.139: E/AndroidRuntime(22270): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.gmapsapp/com.example.gmapsapp.MainActivity}: java.lang.ClassCastException: com.example.gmapsapp.MainActivity cannot be cast to com.google.android.gms.common.GooglePlayServicesClient$ConnectionCallbacks 
05-15 12:18:35.139: E/AndroidRuntime(22270): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2305) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2363) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at android.app.ActivityThread.access$900(ActivityThread.java:161) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1265) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at android.os.Handler.dispatchMessage(Handler.java:102) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at android.os.Looper.loop(Looper.java:157) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at android.app.ActivityThread.main(ActivityThread.java:5356) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at java.lang.reflect.Method.invokeNative(Native Method) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at java.lang.reflect.Method.invoke(Method.java:515) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1265) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1081) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at dalvik.system.NativeStart.main(Native Method) 
05-15 12:18:35.139: E/AndroidRuntime(22270): Caused by: java.lang.ClassCastException: com.example.gmapsapp.MainActivity cannot be cast to com.google.android.gms.common.GooglePlayServicesClient$ConnectionCallbacks 
05-15 12:18:35.139: E/AndroidRuntime(22270): at com.example.gmapsapp.MainActivity.onCreate(MainActivity.java:60) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at android.app.Activity.performCreate(Activity.java:5426) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105) 
05-15 12:18:35.139: E/AndroidRuntime(22270): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2269) 
05-15 12:18:35.139: E/AndroidRuntime(22270): ... 11 more

下面是我MainActivity.java的代碼，讓我知道如果你需要的任何其他文件，看看是否可以用問題幫助的感謝：

package com.example.gmapsapp; 

import java.io.IOException; 
import java.util.List; 

import android.app.Dialog; 
import android.location.Address; 
import android.location.Geocoder; 
import android.os.Bundle; 
import android.support.v4.app.FragmentActivity; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.inputmethod.InputMethodManager; 
import android.widget.EditText; 
import android.widget.Toast; 

import com.google.android.gms.common.ConnectionResult; 
import com.google.android.gms.common.GooglePlayServicesClient.ConnectionCallbacks; 
import com.google.android.gms.common.GooglePlayServicesUtil; 
import com.google.android.gms.common.api.GoogleApiClient; 
import com.google.android.gms.location.LocationClient; 
import com.google.android.gms.maps.CameraUpdate; 
import com.google.android.gms.maps.CameraUpdateFactory; 
import com.google.android.gms.maps.GoogleMap; 
import com.google.android.gms.maps.SupportMapFragment; 
import com.google.android.gms.maps.model.CameraPosition; 
import com.google.android.gms.maps.model.LatLng; 

public class MainActivity extends FragmentActivity implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener{ 

    private static final int GPS_ERRORDIALOG_REQUEST = 9001; 
    @SuppressWarnings("unused") 
    private static final int CONNECTION_FAILURE_RESOLUTION_REQUEST = 9002; 
    GoogleMap mMap; 

    @SuppressWarnings("unused") 
    private static final double SEATTLE_LAT = 47.60621, 
    SEATTLE_LNG =-122.33207, 
    SYDNEY_LAT = -33.867487, 
    SYDNEY_LNG = 151.20699, 
    NEWYORK_LAT = 40.714353, 
    NEWYORK_LNG = -74.005973; 
    private static final float DEFAULTZOOM = 15; 
    @SuppressWarnings("unused") 
    private static final String LOGTAG = "Maps"; 

    LocationClient mLocationClient; 


    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 

     if (servicesOK()) { 
      setContentView(R.layout.activity_map); 

      if (initMap()) { 
//    mMap.setMyLocationEnabled(true); 
       mLocationClient = new LocationClient(this, (ConnectionCallbacks) this, this); 
       mLocationClient.connect(); 

      } 
      else { 
       Toast.makeText(this, "Map not available!", Toast.LENGTH_SHORT).show(); 
      } 
     } 
     else { 
      setContentView(R.layout.activity_main); 
     } 

    } 

    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     // Inflate the menu; this adds items to the action bar if it is present. 
     getMenuInflater().inflate(R.menu.main, menu); 
     return true; 
    } 

    public boolean servicesOK() { 
     int isAvailable = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this); 

     if (isAvailable == ConnectionResult.SUCCESS) { 
      return true; 
     } 
     else if (GooglePlayServicesUtil.isUserRecoverableError(isAvailable)) { 
      Dialog dialog = GooglePlayServicesUtil.getErrorDialog(isAvailable, this, GPS_ERRORDIALOG_REQUEST); 
      dialog.show(); 
     } 
     else { 
      Toast.makeText(this, "Can't connect to Google Play services", Toast.LENGTH_SHORT).show(); 
     } 
     return false; 
    } 

    private boolean initMap() { 
     if (mMap == null) { 
      SupportMapFragment mapFrag = 
        (SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map); 
      mMap = mapFrag.getMap(); 
     } 
     return (mMap != null); 
    } 

    @SuppressWarnings("unused") 
    private void gotoLocation(double lat, double lng) { 
     LatLng ll = new LatLng(lat, lng); 
     CameraUpdate update = CameraUpdateFactory.newLatLng(ll); 
     mMap.moveCamera(update); 
    } 

    private void gotoLocation(double lat, double lng, 
      float zoom) { 
     LatLng ll = new LatLng(lat, lng); 
     CameraUpdate update = CameraUpdateFactory.newLatLngZoom(ll, zoom); 
     mMap.moveCamera(update); 
    } 

    public void geoLocate(View v) throws IOException { 
     hideSoftKeyboard(v); 

     EditText et = (EditText) findViewById(R.id.editText1); 
     String location = et.getText().toString(); 

     Geocoder gc = new Geocoder(this); 
     List<Address> list = gc.getFromLocationName(location, 1); 
     Address add = list.get(0); 
     String locality = add.getLocality(); 
     Toast.makeText(this, locality, Toast.LENGTH_LONG).show(); 

     double lat = add.getLatitude(); 
     double lng = add.getLongitude(); 

     gotoLocation(lat, lng, DEFAULTZOOM); 

    } 

    private void hideSoftKeyboard(View v) { 
     InputMethodManager imm = (InputMethodManager)getSystemService(INPUT_METHOD_SERVICE); 
     imm.hideSoftInputFromWindow(v.getWindowToken(), 0); 
    } 

    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 

     switch (item.getItemId()) { 
     case R.id.mapTypeNone: 
      mMap.setMapType(GoogleMap.MAP_TYPE_NONE); 
      break; 
     case R.id.mapTypeNormal: 
      mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL); 
      break; 
     case R.id.mapTypeSatellite: 
      mMap.setMapType(GoogleMap.MAP_TYPE_SATELLITE); 
      break; 
     case R.id.mapTypeTerrain: 
      mMap.setMapType(GoogleMap.MAP_TYPE_TERRAIN); 
      break; 
     case R.id.mapTypeHybrid: 
      mMap.setMapType(GoogleMap.MAP_TYPE_HYBRID); 
      break; 
     case R.id.gotoCurrentLocation: 
      gotoCurrentLocation(); 
      break; 
     default: 
      break; 
     } 

     return super.onOptionsItemSelected(item); 
    } 

    @Override 
    protected void onStop() { 
     super.onStop(); 
     MapStateManager mgr = new MapStateManager(this); 
     mgr.saveMapState(mMap); 
    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 
     MapStateManager mgr = new MapStateManager(this); 
     CameraPosition position = mgr.getSavedCameraPosition(); 
     if (position != null) { 
      CameraUpdate update = CameraUpdateFactory.newCameraPosition(position); 
      mMap.moveCamera(update); 
      //   This is part of the answer to the code challenge 
      mMap.setMapType(mgr.getSavedMapType()); 
     } 
    } 

    protected void gotoCurrentLocation() { 
    } 

    @Override 
    public void onConnectionFailed(ConnectionResult arg0) { 
     // TODO Auto-generated method stub 

    } 

    @Override 
    public void onConnected(Bundle arg0) { 
     Toast.makeText(this, "Connected to location service", Toast.LENGTH_SHORT).show(); 

    } 

    @Override 
    public void onConnectionSuspended(int arg0) { 
     // TODO Auto-generated method stub 

    } 

}

來源

2014-05-15 user2196650

構造函數的參數是錯誤的。閱讀http://developer.android.com/reference/com/google/android/gms/location/LocationClient.html#LocationClient(android.content.Context，com.google.android.gms.common.GooglePlayServicesClient.ConnectionCallbacks，com .google.android.gms.common.GooglePlayServicesClient.OnConnectionFailedListener） – Raghunandan

謝謝我會給你一個機會！ :) – user2196650

構造函數的第二個和第三個參數的類型爲：

GooglePlayServicesClient.ConnectionCallbacks 
GooglePlayServicesClient.OnConnectionFailedListener

所以，你應該實現這些接口在您的Activity中，如果您指向this。但你已經選擇了另一個類的類似接口 - GoogleApiClient

來源

2014-05-15 11:27:21 nikis

謝謝我會試試這個，讓你知道它是怎麼回事！ :) – user2196650

感謝@尼克斯是的，它正盯着我在代碼中的臉，謝謝你的幫助！ :) – user2196650

不熟悉android apis，但看起來像是ConnectionCallbacks的一個錯誤導入（import com.google.android.gms.common.GooglePlayServicesClient.ConnectionCallbacks;）。當您將其轉換爲ConnectionCallbacks時，將使用該錯誤導入而不是GoogleApiClient.ConnectionCallbacks。

編輯：好的，所以它的其他方式！

來源

2014-05-15 11:36:46

構造函數LocationClient（MainActivity，MainActivity，MainActivity）未定義

回答

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