应该返回一个位置但返回空位置的自定义类

Question

我创建了一个LocationBuddy类，它负责为我需要它的所有其他片段和活动提供位置。我在片段中创建了这个类的一个实例，然后调用方法getUpdatedLocation（）来接收位置。 问题是，当在LocationBuddy类外部调用getUpdatedLocation方法时返回null，我认为我已经初始化了一切正常。

LocationBuddy类

public class LocationBuddy implements GoogleApiClient.ConnectionCallbacks, GoogleApiClient.OnConnectionFailedListener, LocationListener 
{ 
GoogleApiClient client; 
Context context; 

// Private instance variables 
private Location updatedLocation; 
private boolean clientConnected = false; 
private boolean locationUpdated = false; 
private int updateInterval; 
private final static String TAG = "LocationBuddy"; 
private String lastUpdateTime; 
private Location lastLocation; 

// Create the LocationBuddy Object and initialize it with the current context 
public LocationBuddy (Context c, int milliseconds) 
{ 
    this.context = c; 
    this.updateInterval = milliseconds; 
    this.updatedLocation = null; 
    this.lastLocation = null; 
    Log.d(TAG, "LocationBuddy created with an update Interval of "+updateInterval+" milliseconds."); 
} 



// Google Location methods 

@Override 
public void onConnected(@Nullable Bundle bundle) 
{ 
    lastLocation = LocationServices.FusedLocationApi.getLastLocation(client); 
    if (lastLocation != null) 
    { 

     updatedLocation = lastLocation; 

    } 
    // Create a location request called locationRequest 
    LocationRequest locationRequest = LocationRequest.create(); 


    // Set it's priority to high accuracy 
    locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY); 

    // Set it to update to an interval set on object creation 
    locationRequest.setInterval(updateInterval); 

    // If another app is requesting location updates 
    locationRequest.setFastestInterval(updateInterval); 

    // Call requestLocationUpdates in the Api with this request 
    LocationServices.FusedLocationApi.requestLocationUpdates(client, locationRequest, this); 





} 

@Override 
public void onConnectionSuspended(int i) 
{ 
    Log.d(TAG, "The Google API client has been suspended"); 
} 

@Override 
public void onLocationChanged(Location location) 
{ 
    Log.d(TAG, "The location has been changed to " + location.toString()); 
    locationUpdated = true; 
    lastLocation = location; 
    updatedLocation = lastLocation; 

} 

@Override 
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) 
{ 

} 

// Public Methods 
public void initialize() 
{ 

    // Build the GoogleApi Client 
    client = new GoogleApiClient.Builder(context) 
      .addApi(LocationServices.API) 
      .addConnectionCallbacks(this) 
      .addOnConnectionFailedListener(this) 
      .build(); 

    connectToGoogleApiClient(); 

} 




public void connectToGoogleApiClient() 
{ 
    client.connect(); 
    clientConnected = true; 
} 

public void disconnectFromGoogleApiClient() 
{ 
    client.disconnect(); 
    clientConnected = false; 
} 



public String statusReport() 
{ 
    return "Location Buddy: Client connected: "+clientConnected+", Location updated: "+locationUpdated+", Update interval: "+updateInterval; 
} 

public Location getUpdatedLocation() 
{ 
    return updatedLocation; 
} 

public int getUpdateInterval() 
{ 
    return updateInterval; 
} 



public boolean isLocationUpdated() 
{ 

    return locationUpdated; 
} 

public boolean isClientConnected() 
{ 
    return clientConnected; 
} 

// Return a String description of this instance 
public String toString() 
{ 
    return "LocationBuddy[updatedLocation=" + updatedLocation + ",interval=" + updateInterval + ", clientConnected="+clientConnected+ ", locationUpdated="+locationUpdated+"]"; 
} 

} 

这是使用这种LocationBuddy对象PackageListFragment.java类片段。

@Override 
public void onCreate(Bundle savedInstanceState) 
{ 
    super.onCreate(savedInstanceState); 
    courier = new Courier(getContext()); 
    buddy = new LocationBuddy(getContext(), 1000); 
    buddy.initialize(); 

} 

，这是从OnActivityCreated方法调用，PackageListFragment类

这是从logcat的错误：

07-22 16:13:24.351 27538-27538/com.shipwebsource.courier E/AndroidRuntime: FATAL EXCEPTION: main 
                     Process: com.shipwebsource.courier, PID: 27538 
                     java.lang.NullPointerException 
                      at com.shipwebsource.courier.Extras.LocationBuddy.getUpdatedLocation(LocationBuddy.java:146) 
                      at com.shipwebsource.courier.PackageListFragment.onActivityCreated(PackageListFragment.java:306) 
                      at android.support.v4.app.Fragment.performActivityCreated(Fragment.java:1983) 
                      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1092) 
                      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1252) 
                      at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:742) 
                      at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1617) 
                      at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:517) 
                      at android.os.Handler.handleCallback(Handler.java:733) 
                      at android.os.Handler.dispatchMessage(Handler.java:95) 
                      at android.os.Looper.loop(Looper.java:136) 
                      at android.app.ActivityThread.main(ActivityThread.java:5001) 
                      at java.lang.reflect.Method.invokeNative(Native Method) 
                      at java.lang.reflect.Method.invoke(Method.java:515) 
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785) 
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601) 
                      at dalvik.system.NativeStart.main(Native Method) 
07-22 16:13:26.119 27538-28841/com.shipwebsource.courier D/dalvikvm:GC_FOR_ALLOC freed 1427K, 18% free 7077K/8620K, paused 8ms, total 8ms 

Answer 1

你永远不设置client变量是什么。它只创建并从未分配给一个新的GoogleApiClient，直到你设置你的其他东西（从我所知道的）。