融合位置提供程序應用程序崩潰和Logcat瞭解

Question

我做了一個小模塊以使用融合位置提供程序獲取當前位置座標。

我MainActivity.java文件看起來像這樣

TextView globalCoordinates = null; 

private GoogleApiClient mGoogleApiClient; 
private Location mLastLocation; 
@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 

    globalCoordinates = (TextView)findViewById(R.id.textView); 

    mGoogleApiClient = new GoogleApiClient.Builder(this) 
      .addConnectionCallbacks((GoogleApiClient.ConnectionCallbacks) getApplicationContext()) 
      .addOnConnectionFailedListener((GoogleApiClient.OnConnectionFailedListener)getApplicationContext()) 
      .addApi(LocationServices.API) 
      .build(); 
} 

@Override 
public void onConnected(Bundle bundle) { 
    mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient); 
    if (mLastLocation != null) { 
     globalCoordinates.setText("Latitude: " + String.valueOf(mLastLocation.getLatitude())+ "" 
       + "Longitude: " + String.valueOf(mLastLocation.getLongitude())); 
    } 
} 

當我嘗試在我的手機上運行應用程序它提供了以下錯誤： 不幸的是，Module01已經停止。 的logcat的看起來像這樣

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.atifarain.module01/com.example.atifarain.module01.MainActivity}: java.lang.ClassCastException: android.app.Application cannot be cast to com.google.android.gms.common.api.GoogleApiClient$ConnectionCallbacks 
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2200) 
     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2250) 
     at android.app.ActivityThread.access$800(ActivityThread.java:139) 
     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1200) 
     at android.os.Handler.dispatchMessage(Handler.java:102) 
     at android.os.Looper.loop(Looper.java:136) 
     at android.app.ActivityThread.main(ActivityThread.java:5105) 
     at java.lang.reflect.Method.invokeNative(Native Method) 
     at java.lang.reflect.Method.invoke(Method.java:515) 
     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:792) 
     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:608) 
     at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.ClassCastException: android.app.Application cannot be cast to com.google.android.gms.common.api.GoogleApiClient$ConnectionCallbacks 
     at com.example.atifarain.module01.MainActivity.onCreate(MainActivity.java:30) 
     at android.app.Activity.performCreate(Activity.java:5275) 
     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) 
     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2164) 

我怎樣才能解決這個問題？

Answer 1

在MainActivity實現ConnectionCallbacks接口並傳遞MainActivity.this作爲參數addConnectionCallbacks方法：

public class MainActivity extends Activity 
          implements GoogleApiClient.ConnectionCallbacks, 
            GoogleApiClient.OnConnectionFailedListener{ 
    .... 
} 

通行證MainActivity.this：

mGoogleApiClient = new GoogleApiClient.Builder(this) 
        .addConnectionCallbacks(MainActivity.this) 
        .addOnConnectionFailedListener(MainActivity.this) 
        .addApi(LocationServices.API) 
        .build();