我已编写代码来显示地图并在真实设备上运行。但是Map显示为null。
这是我的代码，
package com.example.findproperty;
public class MainActivity extends FragmentActivity implements LocationListener {
private static final String TABLE_NAME = "LatsLongs";
private static final String COLUMN_ID = "_Id";
private static final String Latitude = "Latitude";
private static final String Longitude = "Longitude";
Double Lat;
Double Long;
protected static final int UPDATE_LATLNG = 2;
protected static final int UPDATE_ADDRESS = 0;
public final android.content.Context Context = MainActivity.this;
LocationManager lm;
String textmessage = "";
String phonenumber = "";
GoogleMap mMap;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
int chkGooglePlayServices = GooglePlayServicesUtil
.isGooglePlayServicesAvailable(Context);
if (chkGooglePlayServices != ConnectionResult.SUCCESS) {
GooglePlayServicesUtil.getErrorDialog(chkGooglePlayServices,
(Activity) Context, 1122).show();
} else {
mMap = ((SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map)).getMap();
mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
final boolean isProviderEnabled = lm
.isProviderEnabled(LocationManager.GPS_PROVIDER);
Criteria criteria = new Criteria();
criteria.setAccuracy(Criteria.ACCURACY_FINE);
String locationprovider = lm.getBestProvider(criteria, true);
// Location Update
LocationListener listener = new LocationListener() {
@Override
public void onLocationChanged(Location location) {
mMap.clear();
final CameraPosition cameraPosition = new CameraPosition.Builder()
.target(new LatLng(location.getLatitude(), location
.getLongitude())).zoom(14.0f).build();
final CameraUpdate cameraUpdate = CameraUpdateFactory
.newCameraPosition(cameraPosition);
mMap.moveCamera(cameraUpdate);
}
AlertDialog.Builder dialog = new AlertDialog.Builder(Context)
.setTitle(R.string.RemindEnableGps);
AlertDialog alert = dialog.create();
@Override
public void onProviderDisabled(String provider) {
alert.setCanceledOnTouchOutside(false);
alert.setCancelable(true);
alert.show();
}
@Override
public void onProviderEnabled(String provider) {
alert.dismiss();
}
@Override
public void onStatusChanged(String provider, int status,
Bundle extras) {
}
};
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0,
listener);
final Location mLocation = lm
.getLastKnownLocation(LocationManager.GPS_PROVIDER);
final CameraPosition cameraPosition = new CameraPosition.Builder()
.target(new LatLng(mLocation.getLatitude(), mLocation
.getLongitude())).zoom(14.0f).build();
final CameraUpdate cameraUpdate = CameraUpdateFactory
.newCameraPosition(cameraPosition);
mMap.moveCamera(cameraUpdate);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onProviderDisabled(String provider) {
// TODO Auto-generated method stub
}
@Override
public void onLocationChanged(Location location) {
// TODO Auto-generated method stub
}
}
的Manifest.xml，
<?xml version="1.0" encoding="utf-8"?>
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<permission
android:name="com.example.findproperty.permission.MAPS_RECEIVE"
android:protectionLevel="signature" />
<uses-permission android:name="com.example.findproperty.permission.MAPS_RECEIVE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<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" >
<activity
android:name="com.example.findproperty.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="My_API_KEY" />
</application>
</manifest>
activity_main.xml中，
<?xml version="1.0"?>
<RelativeLayout xmlns:tools="http://schemas.android.com/tools"
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity" >
<fragment
android:id="@+id/map"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_marginBottom="30dp"
android:layout_marginLeft="30dp"
android:layout_marginRight="30dp"
android:layout_marginTop="60dp"
class="com.google.android.gms.maps.SupportMapFragment"
android:clickable="true" />
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/edtSearch"
android:layout_alignLeft="@+id/map"
android:text="Limit Distance:" />
<EditText
android:id="@+id/edtSearch"
android:layout_width="60dp"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/btnSearch"
android:layout_centerHorizontal="true"
android:ems="10"
android:inputType="number" />
<Button
android:id="@+id/btnSearch"
android:layout_width="wrap_content"
android:layout_height="35dp"
android:layout_alignParentTop="true"
android:layout_alignRight="@+id/map"
android:layout_marginRight="14dp"
android:layout_marginTop="15dp"
android:text="Find" />
</RelativeLayout>
当我调试它显示的应用程序时，mMap为null并且mLocation也为null。我没有得到Gps坐标。
这是我的Logcat，
04-24 15:17:53.143: I/ApplicationPackageManager(10248): cscCountry is not German : INS
04-24 15:17:53.182: D/dalvikvm(10248): DexOpt: couldn't find field Landroid/content/res/Configuration;.smallestScreenWidthDp
04-24 15:17:53.182: W/dalvikvm(10248): VFY: unable to resolve instance field 23
04-24 15:17:53.182: D/dalvikvm(10248): VFY: replacing opcode 0x52 at 0x0012
04-24 15:17:53.190: D/dalvikvm(10248): VFY: dead code 0x0014-0018 in Lcom/google/android/gms/common/GooglePlayServicesUtil;.b (Landroid/content/res/Resources;)Z
04-24 15:17:53.331: W/dalvikvm(10248): Unable to resolve superclass of Lmaps/p/s; (425)
04-24 15:17:53.331: W/dalvikvm(10248): Link of class 'Lmaps/p/s;' failed
04-24 15:17:53.331: W/dalvikvm(10248): Unable to resolve superclass of Lmaps/y/bo; (3818)
04-24 15:17:53.331: W/dalvikvm(10248): Link of class 'Lmaps/y/bo;' failed
04-24 15:17:53.339: W/dalvikvm(10248): Unable to resolve superclass of Lmaps/i/k; (4206)
04-24 15:17:53.339: W/dalvikvm(10248): Link of class 'Lmaps/i/k;' failed
04-24 15:17:53.339: E/dalvikvm(10248): Could not find class 'maps.i.k', referenced from method maps.z.ag.a
04-24 15:17:53.339: W/dalvikvm(10248): VFY: unable to resolve new-instance 3538 (Lmaps/i/k;) in Lmaps/z/ag;
04-24 15:17:53.339: D/dalvikvm(10248): VFY: replacing opcode 0x22 at 0x006d
04-24 15:17:53.354: D/dalvikvm(10248): VFY: dead code 0x006f-007f in Lmaps/z/ag;.a (Landroid/view/LayoutInflater;Lcom/google/android/gms/maps/GoogleMapOptions;ZLjava/lang/String;)Lmaps/z/ag;
04-24 15:17:53.448: D/dalvikvm(10248): GC_CONCURRENT freed 367K, 48% free 3090K/5831K, external 688K/1036K, paused 3ms+4ms
04-24 15:17:53.472: I/ApplicationPackageManager(10248): cscCountry is not German : INS
04-24 15:17:53.643: D/dalvikvm(10248): GC_CONCURRENT freed 315K, 45% free 3324K/6023K, external 688K/1036K, paused 4ms+5ms
04-24 15:17:53.768: E/Google Maps Android API(10248): Failed to load map. Could not contact Google servers.
04-24 15:17:53.870: W/dalvikvm(10248): threadid=1: thread exiting with uncaught exception (group=0x40018578)
04-24 15:17:53.870: E/AndroidRuntime(10248): FATAL EXCEPTION: main
04-24 15:17:53.870: E/AndroidRuntime(10248): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.findproperty/com.example.findproperty.MainActivity}: java.lang.NullPointerException
04-24 15:17:53.870: E/AndroidRuntime(10248): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1651)
04-24 15:17:53.870: E/AndroidRuntime(10248): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1667)
04-24 15:17:53.870: E/AndroidRuntime(10248): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
04-24 15:17:53.870: E/AndroidRuntime(10248): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:935)
04-24 15:17:53.870: E/AndroidRuntime(10248): at android.os.Handler.dispatchMessage(Handler.java:99)
04-24 15:17:53.870: E/AndroidRuntime(10248): at android.os.Looper.loop(Looper.java:130)
04-24 15:17:53.870: E/AndroidRuntime(10248): at android.app.ActivityThread.main(ActivityThread.java:3687)
04-24 15:17:53.870: E/AndroidRuntime(10248): at java.lang.reflect.Method.invokeNative(Native Method)
04-24 15:17:53.870: E/AndroidRuntime(10248): at java.lang.reflect.Method.invoke(Method.java:507)
04-24 15:17:53.870: E/AndroidRuntime(10248): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
04-24 15:17:53.870: E/AndroidRuntime(10248): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:625)
04-24 15:17:53.870: E/AndroidRuntime(10248): at dalvik.system.NativeStart.main(Native Method)
04-24 15:17:53.870: E/AndroidRuntime(10248): Caused by: java.lang.NullPointerException
04-24 15:17:53.870: E/AndroidRuntime(10248): at com.example.findproperty.MainActivity.onCreate(MainActivity.java:130)
04-24 15:17:53.870: E/AndroidRuntime(10248): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-24 15:17:53.870: E/AndroidRuntime(10248): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1615)
04-24 15:17:53.870: E/AndroidRuntime(10248): ... 11 more
04-24 15:17:54.089: D/dalvikvm(10248): GC_CONCURRENT freed 311K, 44% free 3542K/6279K, external 929K/1036K, paused 4ms+4ms
该设备已安装google-play-services。并启用了GPS。 但是地图显示为空。
我的移动设备无法访问互联网。
请有人帮忙!!!
答案 0 :(得分：0)
在这部分：
我认为“My_API_KEY”部分已被您的实际API密钥替换，对吧？
此行被抛出异常吗？
mMap.setMapType（GoogleMap.MAP_TYPE_NORMAL）;
看一下这个链接：
Google Play Service - SupportMapFragment.getMap() always returning null