Question

我创建了一个小模块，使用融合位置提供程序获取当前位置坐标。

我的 MainActivity.java 文件如下所示

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()));
    }
}

当我尝试在我的手机上运行该应用时，会出现以下错误： 不幸的是，Module01已停止。 Logcat 看起来像这样

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)

如何解决此问题？

Answer 1

在ConnectionCallbacks中实施MainActivity界面，并将MainActivity.this作为参数传递给addConnectionCallbacks方法：

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

通过MainActivity.this：

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

融合位置提供程序应用程序崩溃和Logcat理解

1 个答案: