我一直试图让一个简单的应用程序运行，显示一个地图，但它不会工作。这是我使用的代码：
MainActivity.java：
package info.androidhive.googlemapsv2;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.MapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.MarkerOptions;
public class MainActivity extends FragmentActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// Get a handle to the Map Fragment
GoogleMap map = ((MapFragment) getFragmentManager()
.findFragmentById(R.id.map)).getMap();
LatLng sydney = new LatLng(-33.867, 151.206);
map.setMyLocationEnabled(true);
map.moveCamera(CameraUpdateFactory.newLatLngZoom(sydney, 13));
map.addMarker(new MarkerOptions()
.title("Sydney")
.snippet("The most populous city in Australia.")
.position(sydney));
}
}
GoogleMapsV2 Manifest：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="info.androidhive.googlemapsv2"
android:versionCode="1"
android:versionName="1.0" >
<permission
android:name="info.androidhive.googlemapsv2.permission.MAPS_RECEIVE"
android:protectionLevel="signature" />
<uses-permission android:name="info.androidhive.googlemapsv2.permission.MAPS_RECEIVE" />
<uses-sdk
android:minSdkVersion="12"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<!-- Required to show current location -->
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<!-- Required OpenGL ES 2.0. for Maps V2 -->
<uses-feature
android:glEsVersion="0x00020000"
android:required="true" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name">
<uses-library
android:name="com.google.android.maps"
android:required="true" />
<activity
android:name="info.androidhive.googlemapsv2.MainActivity"
android:label="@string/app_name"
android:theme="@style/AppBaseTheme">
<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.gms.version"
android:value="@integer/google_play_services_version" />
<!-- Goolge API Key -->
<meta-data
android:name="com.google.android.maps.v2.API_KEY"
android:value="AIzaSyCg5_f6_CdvyUBDuBf_gU8L39YyiQZdEh0" />
</application>
</manifest>
activity_main.xml中：
<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"
tools:context=".MainActivity" >
<TextView
android:id="@+id/tv_location"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<fragment
android:id="@+id/map"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_below="@id/tv_location"
class="com.google.android.gms.maps.SupportMapFragment" />
</RelativeLayout>
logcat的：
03-16 12:53:10.778: W/dalvikvm(32321): threadid=1: thread exiting with uncaught exception (group=0x40db3600)
03-16 12:53:10.778: E/AndroidRuntime(32321): FATAL EXCEPTION: main
03-16 12:53:10.778: E/AndroidRuntime(32321): java.lang.RuntimeException: Unable to start activity ComponentInfo{info.androidhive.googlemapsv2/info.androidhive.googlemapsv2.MainActivity}: java.lang.NullPointerException
03-16 12:53:10.778: E/AndroidRuntime(32321): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2332)
03-16 12:53:10.778: E/AndroidRuntime(32321): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2368)
03-16 12:53:10.778: E/AndroidRuntime(32321): at android.app.ActivityThread.access$600(ActivityThread.java:151)
03-16 12:53:10.778: E/AndroidRuntime(32321): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1330)
03-16 12:53:10.778: E/AndroidRuntime(32321): at android.os.Handler.dispatchMessage(Handler.java:99)
03-16 12:53:10.778: E/AndroidRuntime(32321): at android.os.Looper.loop(Looper.java:155)
03-16 12:53:10.778: E/AndroidRuntime(32321): at android.app.ActivityThread.main(ActivityThread.java:5536)
03-16 12:53:10.778: E/AndroidRuntime(32321): at java.lang.reflect.Method.invokeNative(Native Method)
03-16 12:53:10.778: E/AndroidRuntime(32321): at java.lang.reflect.Method.invoke(Method.java:511)
03-16 12:53:10.778: E/AndroidRuntime(32321): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1074)
03-16 12:53:10.778: E/AndroidRuntime(32321): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:841)
03-16 12:53:10.778: E/AndroidRuntime(32321): at dalvik.system.NativeStart.main(Native Method)
03-16 12:53:10.778: E/AndroidRuntime(32321): Caused by: java.lang.NullPointerException
03-16 12:53:10.778: E/AndroidRuntime(32321): at info.androidhive.googlemapsv2.MainActivity.onCreate(MainActivity.java:21)
03-16 12:53:10.778: E/AndroidRuntime(32321): at android.app.Activity.performCreate(Activity.java:5066)
03-16 12:53:10.778: E/AndroidRuntime(32321): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1102)
03-16 12:53:10.778: E/AndroidRuntime(32321): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2288)
03-16 12:53:10.778: E/AndroidRuntime(32321): ... 11 more
03-16 12:53:12.858: D/Process(32321): killProcess, pid=32321
03-16 12:53:12.858: D/Process(32321): dalvik.system.VMStack.getThreadStackTrace(Native Method)
03-16 12:53:12.858: D/Process(32321): java.lang.Thread.getStackTrace(Thread.java:599)
03-16 12:53:12.858: D/Process(32321): android.os.Process.killProcess(Process.java:956)
03-16 12:53:12.858: D/Process(32321): com.android.internal.os.RuntimeInit$UncaughtHandler.uncaughtException(RuntimeInit.java:108)
03-16 12:53:12.858: D/Process(32321): java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:693)
03-16 12:53:12.858: D/Process(32321): java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:690)
03-16 12:53:12.858: D/Process(32321): dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：3)
当您使用SupportMapFragment时，您应该使用
GoogleMap map = ((SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map)).getMap();
而不是
GoogleMap map = ((MapFragment) getFragmentManager()
.findFragmentById(R.id.map)).getMap();