android - java.lang.NullPointerException 谷歌地图 API 2

Question

我正在尝试在没有 movecamera 的情况下执行此 google map v2，它工作正常，但我尝试使用 movecamera 并出现问题。我确实将 google-play-services-lib 添加到我的项目中，并且我使用了 intellij idea在具有谷歌播放服务的设备 android 4.0.4 上运行

日志

12-14 00:57:30.978  26218-26218/com.example.maptest2 E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.maptest2/com.example.maptest2.MyActivity}: java.lang.NullPointerException
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1967)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
        at android.app.ActivityThread.access$600(ActivityThread.java:127)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4441)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:565)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
        at com.example.maptest2.MyActivity.onCreate(MyActivity.java:37)
        at android.app.Activity.performCreate(Activity.java:4465)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1931)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1992)
            at android.app.ActivityThread.access$600(ActivityThread.java:127)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1158)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4441)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            atcom.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:74
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:565)
            at dalvik.system.NativeStart.main(Native Method)

activity_map.xml

        <?xml version="1.0" encoding="utf-8"?>

    <fragment xmlns:android="http://schemas.android.com/apk/res/android"
              xmlns:map="http://schemas.android.com/apk/res-auto"
                  android:id="@+id/map"
                  android:name="com.google.android.gms.maps.MapFragment"
                  android:orientation="vertical"
                  android:layout_width="match_parent"
                  android:layout_height="match_parent"
                  map:cameraTargetLat="35.721988"
                  map:cameraTargetLng="51.42128"
                  map:cameraZoom="10"
            />

MyActivity.java

        package com.example.maptest2;

    import android.UnusedStub;
    import android.app.Activity;
    import android.app.Dialog;
    import android.app.Fragment;
    import android.app.FragmentTransaction;
    import android.os.Bundle;
    import android.view.Menu;
    import android.widget.Toast;
    import com.google.android.gms.common.ConnectionResult;
    import com.google.android.gms.common.GooglePlayServicesUtil;
    import com.google.android.gms.maps.*;
    import com.google.android.gms.maps.model.LatLng;

    public class MyActivity extends Activity {

        private static final int GPS_ERRORDIALOG_REQUEST = 9001;
        private GoogleMap map  ;


        @SuppressWarnings("unused")
        private static final double Eram_park_Lat=35.7192,
        Eram_park_Lng=51.294422;

        private static final float DEFAULZOOM =13;
        /**
         * Called when the activity is first created.
         */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            if(servicesOK()){
                Toast.makeText(this, "Ready to map!", Toast.LENGTH_SHORT).show();
                setContentView(R.layout.activity_maps);
                LatLng ll = new LatLng(Eram_park_Lat, Eram_park_Lng);
                map.moveCamera(CameraUpdateFactory.newLatLngZoom(ll,DEFAULZOOM));
            }
            else {
                setContentView(R.layout.main);
            }
        }

        public boolean servicesOK() {
            int isAvailable = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);

            if (isAvailable == ConnectionResult.SUCCESS) {
                return true;
            }
            else if (GooglePlayServicesUtil.isUserRecoverableError(isAvailable)) {
                Dialog dialog = GooglePlayServicesUtil.getErrorDialog(isAvailable, this, GPS_ERRORDIALOG_REQUEST);
                dialog.show();
            }
            else {
                Toast.makeText(this, "Can't connect to Google Play services", Toast.LENGTH_SHORT).show();
            }
            return false;
        }



    }

AndroidManifest.xml

        <?xml version="1.0" encoding="utf-8"?>
    <manifest xmlns:android="http://schemas.android.com/apk/res/android"
              package="com.example.maptest2"
              android:versionCode="1"
              android:versionName="1.0">

        <uses-sdk android:minSdkVersion="10" android:targetSdkVersion="18"/>

        <permission
                android:name="com.example.maptest2.permission.MAPS_RECEIVE"
                android:protectionLevel="signature"/>

        <uses-permission android:name="com.example.maptest2.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"/>
        <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:label="@string/app_name" android:icon="@drawable/ic_launcher">
            <activity android:name="MyActivity"
                      android:label="@string/app_name">
                <intent-filter>
                    <action android:name="android.intent.action.MAIN"/>
                    <category android:name="android.intent.category.LAUNCHER"/>
                </intent-filter>
            </activity>
            <uses-library android:name="com.google.android.maps"/>
            <meta-data
                    android:name="com.google.android.gms.version"
                    android:value="@integer/google_play_services_version" />
            <meta-data
                    android:name="com.google.android.maps.v2.API_KEY"
                    android:value="api key"/>

        </application>
    </manifest>

Answer 1

您必须初始化您的 GoogleMap 对象，如下所示:

map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();

请仔细关注 https://developers.google.com/maps/documentation/android/map , 这会让你继续前进