我正在尝试使用导航栏和Google Map API构建应用程序。
我遵循了以下两个：
http://www.androidhive.info/2015/04/android-getting-started-with-material-design/
http://blog.teamtreehouse.com/beginners-guide-location-android
教程，当我将地图教程放入导航栏中的一个片段时，我收到了这些错误：
myGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
错误发生在＆＃34; this＆＃34;在Builder内部。
这是我完整的课程代码：
package com.clark.androbotics.projectapp;
import android.app.Activity;
import android.content.IntentSender;
import android.location.Location;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import com.google.android.gms.common.ConnectionResult;
import com.google.android.gms.common.api.GoogleApiClient;
import com.google.android.gms.location.LocationListener;
import com.google.android.gms.location.LocationRequest;
import com.google.android.gms.location.LocationServices;
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.UiSettings;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
public class MapFragment extends Fragment implements
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener {
public static final String TAG = MapFragment.class.getSimpleName();
private final static int CONNECTION_FAILURE_RESOLUTION_REQUEST = 9000;
private GoogleApiClient myGoogleApiClient;
private LocationRequest myLocationRequest;
private GoogleMap mMap; // Might be null if Google Play services APK is not available.
public MapFragment() {
// Required empty public constructor
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setUpMapIfNeeded();
myGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
// Create the LocationRequest object
myLocationRequest = LocationRequest.create()
.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
.setInterval(10 * 1000) // 10 seconds, in milliseconds
.setFastestInterval(1 * 1000); // 1 second, in milliseconds
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_map, container, false);
// Inflate the layout for this fragment
return rootView;
}
@Override
public void onResume() {
super.onResume();
setUpMapIfNeeded();
myGoogleApiClient.connect();
}
@Override
public void onPause() {
super.onPause();
if (myGoogleApiClient.isConnected()) {
LocationServices.FusedLocationApi.removeLocationUpdates(myGoogleApiClient, this);
myGoogleApiClient.disconnect();
}
}
/**
* Sets up the map if it is possible to do so (i.e., the Google Play services APK is correctly
* installed) and the map has not already been instantiated.. This will ensure that we only ever
* call {@link #setUpMap()} once when {@link #mMap} is not null.
* <p/>
* If it isn't installed {@link com.google.android.gms.maps.SupportMapFragment} (and
* {@link com.google.android.gms.maps.MapView MapView}) will show a prompt for the user to
* install/update the Google Play services APK on their device.
* <p/>
* A user can return to this FragmentActivity after following the prompt and correctly
* installing/updating/enabling the Google Play services. Since the FragmentActivity may not
* have been completely destroyed during this process (it is likely that it would only be
* stopped or paused), {@link #onCreate(Bundle)} may not be called again so we should call this
* method in {@link #onResume()} to guarantee that it will be called.
*/
private void setUpMapIfNeeded() {
// Do a null check to confirm that we have not already instantiated the map.
if (mMap == null) {
// Try to obtain the map from the SupportMapFragment.
mMap = ((SupportMapFragment) getFragmentManager().findFragmentById(R.id.map))
.getMap();
// Check if we were successful in obtaining the map.
if (mMap != null) {
setUpMap();
}
}
}
/**
* This is where we can add markers or lines, add listeners or move the camera. In this case, we
* just add a marker near Africa.
* <p/>
* This should only be called once and when we are sure that {@link #mMap} is not null.
*/
private void setUpMap() {
UiSettings mapSettings;
mapSettings = mMap.getUiSettings();
mapSettings.setZoomControlsEnabled(true);
mMap.setMapType(GoogleMap.MAP_TYPE_HYBRID);
}
private void handleNewLocation(Location myLocation) {
double currentLatitude = myLocation.getLatitude();
double currentLongitude = myLocation.getLongitude();
LatLng latLng = new LatLng(currentLatitude, currentLongitude);
MarkerOptions options = new MarkerOptions().position(latLng).title("I am here!");
mMap.addMarker(options);
mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(latLng, 17));
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
}
@Override
public void onDetach() {
super.onDetach();
}
@Override
public void onConnected(Bundle bundle) {
Location myLocation = LocationServices.FusedLocationApi.getLastLocation(myGoogleApiClient);
if (myLocation == null) {
LocationServices.FusedLocationApi.requestLocationUpdates(myGoogleApiClient, myLocationRequest, this);
}
else {
handleNewLocation(myLocation);
};
}
@Override
public void onConnectionSuspended(int i) {
}
@Override
public void onLocationChanged(Location location) {
}
@Override
public void onConnectionFailed(ConnectionResult connectionResult) {
if (connectionResult.hasResolution()) {
try {
// Start an Activity that tries to resolve the error
connectionResult.startResolutionForResult(this, CONNECTION_FAILURE_RESOLUTION_REQUEST);
} catch (IntentSender.SendIntentException e) {
e.printStackTrace();
}
} else {
Log.i(TAG, "Location services connection failed with code " + connectionResult.getErrorCode());
}
}
}
我相信我添加了必要的导入，但我似乎无法修复它。
我是Android开发的新手，所以我不太确定这似乎是什么问题。
编辑：应用程序运行但每当我转到此片段时强制关闭。
似乎有关于空对象引用的错误。
这是我的logcat：
05-08 15:42:20.468 24080-24080/com.clark.androbotics.projectapp E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.clark.androbotics.projectapp, PID: 24080
java.lang.NullPointerException: Attempt to invoke virtual method 'com.google.android.gms.maps.GoogleMap com.google.android.gms.maps.SupportMapFragment.getMap()' on a null object reference
at com.clark.androbotics.projectapp.MapFragment.setUpMapIfNeeded(MapFragment.java:108)
at com.clark.androbotics.projectapp.MapFragment.onCreate(MapFragment.java:46)
at android.support.v4.app.Fragment.performCreate(Fragment.java:1763)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:915)
at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1136)
at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:739)
at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1499)
at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:456)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5293)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:699)
我相信片段上有.getMap的内容，但我不确定。我也试过把它放在OnCreateView中，但我仍然有同样的错误。
非常感谢任何帮助。
答案 0 :(得分：2)
GoogleApiClient.Builder构造函数使用Context，例如Activity，Service等，但您传递this，在这种情况下是Fragment {1}}（不会延长Context）。
而是传入getActivity()，它会返回当前附加到的片段Activity：
myGoogleApiClient = new GoogleApiClient.Builder(getActivity())
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();