Question

所以我跟随一个关于使用Google Maps V2构建移动应用程序的Lynda.com教程，我正在开发一个部分，让您创建一个地图应用程序，以编程方式查找位置而不是依赖在setMyLocationEnabled(true)方法上。所以我跟着代码，每次我去运行应用程序时崩溃并在logcat中给我以下错误：

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

这是我的MainActivity.java中的代码，如果您需要任何其他文件，请告知我们您是否可以帮助解决此问题，谢谢：

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

    }

}

Answer 1

构造函数的第二个和第三个参数的类型为：

GooglePlayServicesClient.ConnectionCallbacks
GooglePlayServicesClient.OnConnectionFailedListener

因此，如果您指向Activity，则应在this中实施这些界面。但是你已经从另一个类中挑选了类似的接口 - GoogleApiClient

Answer 2

不熟悉android apis，但看起来像是一个糟糕的ConnectionCallbacks导入（导入com.google.android.gms.common.GooglePlayServicesClient.ConnectionCallbacks;）。当您使用该错误导入而不是GoogleApiClient.ConnectionCallbacks转换为ConnectionCallbacks时。

编辑：好吧，反过来了！

构造函数LocationClient（MainActivity，MainActivity，MainActivity）未定义

2 个答案: