我正在开发一个小型的Android应用程序,每当我调用GoogleMap map = ((SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.map)).getMap()
时,它总是返回null。
我正在尝试使用带有Google Play的API 17在设备上运行此应用程序。
MapActivity:
public class MapActivity extends FragmentActivity implements LocationSource, LocationListener {
private static final String TAG = "MapActivity";
private String device = android.os.Build.MODEL;
private static final String UPDATE_LOC_URL = "http://lab.uzlabina.cz/~vongrad/Tracker/update_loc.php";
private static final String LOAD_LOCATIONS = "http://lab.uzlabina.cz/~vongrad/Tracker/load_locations.php";
private static final int ADD_MAP_PIN = 1;
private Controller controller;
private LocationManager locationManager;
private OnLocationChangedListener locListener;
private GoogleMap map;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
controller = Controller.getInstance(new User());
controller.setUserName(device);
locationManager = (LocationManager)getSystemService(LOCATION_SERVICE);
if (locationManager != null){
boolean isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
boolean isNetworkEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
Log.d(TAG, "GPS " + isGPSEnabled + "Net " + isNetworkEnabled);
if (isGPSEnabled){
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 50L, 1F, this);
}
else if (isNetworkEnabled){
locationManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 500L, 10F, this);
}
else{
Toast.makeText(this, "GPS is disabled", Toast.LENGTH_LONG);
}
}
else
{
Toast.makeText(this, "Something went wrrong", Toast.LENGTH_LONG);
}
setUpMapIfNeeded();
}
public void onResume(){
//updateLocation.start();
super.onResume();
//setUpMapIfNeeded();
if (locationManager != null){
map.setMyLocationEnabled(true);
}
}
public void onPause(){
//loadFriendsLocations.stop();
if (locationManager != null){
locationManager.removeUpdates(this);
}
super.onPause();
}
private void setUpMapIfNeeded() {
if (map == null){
map = ((SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.map)).getMap();
map.setLocationSource(this);
if (map != null){
setUpMap();
}
}
}
private void setUpMap() {
map.setMyLocationEnabled(true);
loadFriendsLocations.start();
}
布局:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MapActivity" >
<TextView
android:id="@+id/header"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
<fragment
android:id="@+id/map"
android:name="com.google.android.gms.maps.SupportMapFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</RelativeLayout>
清单:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="cz.vongrad.locator"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="11"
android:targetSdkVersion="17" />
<permission
android:name="cz.vongrad.locator.permission.MAPS_RECEIVE"
android:protectionLevel="signature"/>
<uses-permission android:name="cz.vongrad.locator.permission.MAPS_RECEIVE"/>
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES"/>
<!-- The following two permissions are not required to use
Google Maps Android API v2, but are recommended. -->
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-feature
android:glEsVersion="0x00020000"
android:required="true"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" android:debuggable="true">
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="blabla"/>
<activity
android:name="cz.vongrad.locator.MapActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
logcat的:
10-05 19:40:13.284: E/AndroidRuntime(2697): FATAL EXCEPTION: main
10-05 19:40:13.284: E/AndroidRuntime(2697): java.lang.RuntimeException: Unable to start activity ComponentInfo{cz.vongrad.locator/cz.vongrad.locator.MapActivity}: java.lang.NullPointerException
10-05 19:40:13.284: E/AndroidRuntime(2697): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
10-05 19:40:13.284: E/AndroidRuntime(2697): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
10-05 19:40:13.284: E/AndroidRuntime(2697): at android.app.ActivityThread.access$600(ActivityThread.java:141)
10-05 19:40:13.284: E/AndroidRuntime(2697): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
10-05 19:40:13.284: E/AndroidRuntime(2697): at android.os.Handler.dispatchMessage(Handler.java:99)
10-05 19:40:13.284: E/AndroidRuntime(2697): at android.os.Looper.loop(Looper.java:137)
10-05 19:40:13.284: E/AndroidRuntime(2697): at android.app.ActivityThread.main(ActivityThread.java:5041)
10-05 19:40:13.284: E/AndroidRuntime(2697): at java.lang.reflect.Method.invokeNative(Native Method)
10-05 19:40:13.284: E/AndroidRuntime(2697): at java.lang.reflect.Method.invoke(Method.java:511)
10-05 19:40:13.284: E/AndroidRuntime(2697): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
10-05 19:40:13.284: E/AndroidRuntime(2697): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
10-05 19:40:13.284: E/AndroidRuntime(2697): at dalvik.system.NativeStart.main(Native Method)
10-05 19:40:13.284: E/AndroidRuntime(2697): Caused by: java.lang.NullPointerException
10-05 19:40:13.284: E/AndroidRuntime(2697): at cz.vongrad.locator.MapActivity.setUpMapIfNeeded(MapActivity.java:115)
10-05 19:40:13.284: E/AndroidRuntime(2697): at cz.vongrad.locator.MapActivity.onCreate(MapActivity.java:86)
10-05 19:40:13.284: E/AndroidRuntime(2697): at android.app.Activity.performCreate(Activity.java:5104)
10-05 19:40:13.284: E/AndroidRuntime(2697): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
10-05 19:40:13.284: E/AndroidRuntime(2697): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
10-05 19:40:13.284: E/AndroidRuntime(2697): ... 11 more
我将不胜感激任何建议。 提前谢谢!
答案 0 :(得分:0)
在初始化locationmanager之前尝试尽早调用这个setUpMapIfNeeded()几行
setContentView(R.layout.activity_main);
controller = Controller.getInstance(new User());
controller.setUserName(device);
setUpMapIfNeeded();