我正在使用SupportMapFrgment来确保我的应用程序中Google Maps API的向后兼容性。
似乎在4.1上加载地图就好了，但我在2.3.4上崩溃了。
这是我的代码：
private String getCurrentLocation() {
LocationManager service = (LocationManager) getSystemService(LOCATION_SERVICE);
Criteria criteria = new Criteria();
String provider = service.getBestProvider(criteria, false);
Location location = service.getLastKnownLocation(provider);
LatLng userLocation = new LatLng(location.getLatitude(),
location.getLongitude());
Geocoder geocoder = new Geocoder(this, Locale.getDefault());
List<Address> addresses = null;
String addressText = "";
try {
while (addresses == null) {
addresses = geocoder.getFromLocation(userLocation.latitude,
userLocation.longitude, 1);
}
if (addresses != null && addresses.size() > 0) {
Address address = addresses.get(0);
addressText = String.format(
"%s, %s, %s",
address.getMaxAddressLineIndex() > 0 ? address
.getAddressLine(0) : "", address.getLocality(),
address.getCountryName());
}
} catch (IOException e) {
e.printStackTrace();
}
return addressText;
}
这是我检索地图的地方：
map = ((SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map))
.getMap();
XML布局：
<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/location_stuff"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/greenish"
android:orientation="vertical" >
<RelativeLayout
android:id="@+id/location_header"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:background="@color/greenish" >
<RelativeLayout
android:id="@+id/cancel_btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_centerVertical="true"
android:layout_marginLeft="20dp"
android:background="@drawable/done_rounded_btn"
android:gravity="center" >
<TextView
android:id="@+id/retake_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:layout_marginTop="10dp"
android:gravity="center"
android:paddingLeft="7dp"
android:paddingRight="7dp"
android:text="@string/cancel"
android:textAllCaps="true"
android:textColor="#FFFFFF"
android:textSize="16sp" />
</RelativeLayout>
<TextView
android:id="@+id/location_txt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:gravity="center_vertical"
android:text="@string/location_map"
android:textAllCaps="true"
android:textColor="@color/done_color"
android:textSize="16sp" />
</RelativeLayout>
<fragment
android:layout_weight="6"
android:id="@+id/map"
android:layout_marginLeft="10dp"
android:layout_marginRight="10dp"
android:layout_width="match_parent"
android:layout_height="0dp"
class="com.google.android.gms.maps.SupportMapFragment"/>
<RelativeLayout
android:id="@+id/save_location_layout"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_weight="1"
android:background="@color/greenish" >
<LinearLayout
android:id="@+id/delete_btn"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:layout_marginLeft="25dp"
android:layout_marginRight="25dp"
android:background="@drawable/done_rounded_btn"
android:orientation="horizontal"
android:paddingBottom="7dip"
android:paddingTop="7dip"
android:weightSum="7" >
<TextView
android:id="@+id/delete_txt"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_weight="6"
android:background="@null"
android:paddingLeft="10dp"
android:text="@string/save_location"
android:textAllCaps="true"
android:textColor="@color/white"
android:textSize="18sp" />
<ImageView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:layout_weight="1"
android:contentDescription="@string/hello_world"
android:paddingLeft="10dp"
android:paddingRight="10dp"
android:src="@drawable/input_map_white" />
</LinearLayout>
</RelativeLayout>
</LinearLayout>
和堆栈跟踪：
09-06 10:15:14.366: E/AndroidRuntime(10352): FATAL EXCEPTION: main
09-06 10:15:14.366: E/AndroidRuntime(10352): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.captoom/ro.gebs.captoom.activities.LocationActivity}: java.lang.NullPointerException
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1653)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1669)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.os.Handler.dispatchMessage(Handler.java:99)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.os.Looper.loop(Looper.java:130)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.ActivityThread.main(ActivityThread.java:3737)
09-06 10:15:14.366: E/AndroidRuntime(10352): at java.lang.reflect.Method.invokeNative(Native Method)
09-06 10:15:14.366: E/AndroidRuntime(10352): at java.lang.reflect.Method.invoke(Method.java:507)
09-06 10:15:14.366: E/AndroidRuntime(10352): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:894)
09-06 10:15:14.366: E/AndroidRuntime(10352): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:652)
09-06 10:15:14.366: E/AndroidRuntime(10352): at dalvik.system.NativeStart.main(Native Method)
09-06 10:15:14.366: E/AndroidRuntime(10352): Caused by: java.lang.NullPointerException
09-06 10:15:14.366: E/AndroidRuntime(10352): at ro.gebs.captoom.activities.LocationActivity.getCurrentLocation(LocationActivity.java:131)
09-06 10:15:14.366: E/AndroidRuntime(10352): at ro.gebs.captoom.activities.LocationActivity.retrieveLocation(LocationActivity.java:98)
09-06 10:15:14.366: E/AndroidRuntime(10352): at ro.gebs.captoom.activities.LocationActivity.onCreate(LocationActivity.java:80)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1617)
09-06 10:15:14.366: E/AndroidRuntime(10352): ... 11 more
09-06 10:15:14.366: E/AndroidRuntime(10352): [Blue Error Handler] Make Debugging Report file for main
09-06 10:15:14.366: E/AndroidRuntime(10352): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.captoom/ro.gebs.captoom.activities.LocationActivity}: java.lang.NullPointerException
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1653)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1669)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.os.Handler.dispatchMessage(Handler.java:99)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.os.Looper.loop(Looper.java:130)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.ActivityThread.main(ActivityThread.java:3737)
09-06 10:15:14.366: E/AndroidRuntime(10352): at java.lang.reflect.Method.invokeNative(Native Method)
09-06 10:15:14.366: E/AndroidRuntime(10352): at java.lang.reflect.Method.invoke(Method.java:507)
09-06 10:15:14.366: E/AndroidRuntime(10352): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:894)
09-06 10:15:14.366: E/AndroidRuntime(10352): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:652)
09-06 10:15:14.366: E/AndroidRuntime(10352): at dalvik.system.NativeStart.main(Native Method)
09-06 10:15:14.366: E/AndroidRuntime(10352): Caused by: java.lang.NullPointerException
09-06 10:15:14.366: E/AndroidRuntime(10352): at ro.gebs.captoom.activities.LocationActivity.getCurrentLocation(LocationActivity.java:131)
09-06 10:15:14.366: E/AndroidRuntime(10352): at ro.gebs.captoom.activities.LocationActivity.retrieveLocation(LocationActivity.java:98)
09-06 10:15:14.366: E/AndroidRuntime(10352): at ro.gebs.captoom.activities.LocationActivity.onCreate(LocationActivity.java:80)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
09-06 10:15:14.366: E/AndroidRuntime(10352): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1617)
09-06 10:15:14.366: E/AndroidRuntime(10352): ... 11 more
任何帮助都非常感激。
修改
问题在于设备设置，我只需要启用：
设置 - ＆gt;应用程序设置 - ＆gt;发展 - ＆gt;允许模拟位置
设置 - ＆gt;位置＆amp;安全 - ＆gt;使用无线网络
感谢您的所有答案。
答案 0 :(得分：1)
getLastKnownLocation不会造成崩溃。
正如我们从您的stacktrace中看到的那样
09-06 10:15:14.366: E/AndroidRuntime(10352): Caused by: java.lang.NullPointerException
09-06 10:15:14.366: E/AndroidRuntime(10352): at ro.gebs.captoom.activities.LocationActivity.getCurrentLocation(LocationActivity.java:131)
您正试图在没有任何内容的引用上调用方法或null。
getLastKnownLocation可以返回null。你必须处理它。
答案 1 :(得分：1)
getLastKnownLocation方法将返回最后一个缓存位置，因此它将返回null，直到您指定的提供程序至少获得一次更新。您
需要有一个应用程序请求（并接收）至少一次更新
在致电getLastKnownLocation()之前的会话。
所以你需要处理这种情况。
尝试以下，
location = locationManager.getLastKnownLocation(provider);
LatLng userLocation = null;
if (location != null) {
old_latitude=location.getLatitude();
old_longitude=location.getLongitude();
userLocation = new LatLng(old_latitude,old_longitude);
this.onLocationChanged(location);
}