Android 当我想从活动切换到MapActivity时，得到一个奇怪的NullPointerException

当我尝试切换到MapActivity时，会得到一个NullPointerException

我在super.oncreatesavedInstanceState得到它；调用，它必须是public void onCreateBundle savedInstanceState方法中的第一行。在调试器中，我可以看到savedInstanceState确实为null

这是我用来切换到该活动的代码，当单击按钮时会调用它。在另一个正常的活动中，效果很好。它从启动活动内部启动，方法从OnTouchListener调用

正常活动的文档说明

如果活动在之前关闭后重新初始化，则此捆绑包包含它最近在onSaveInstanceStateBundle中提供的数据。注意：否则为空

所以我猜它的意图是null，因为MapActivity只是普通活动的扩展。 那么，uehm，我在监督什么，出了什么问题

来自LogCat的错误日志：

03-28 09:09:54.744: E/AndroidRuntime(1172): FATAL EXCEPTION: main
03-28 09:09:54.744: E/AndroidRuntime(1172): java.lang.RuntimeException: Unable to start activity ComponentInfo{m.p/m.p.LiveActivity}: java.lang.NullPointerException
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1815)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1831)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android.app.ActivityThread.access$500(ActivityThread.java:122)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1024)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android.os.Looper.loop(Looper.java:132)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android.app.ActivityThread.main(ActivityThread.java:4123)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at java.lang.reflect.Method.invokeNative(Native Method)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at java.lang.reflect.Method.invoke(Method.java:491)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at dalvik.system.NativeStart.main(Native Method)
**03-28 09:09:54.744: E/AndroidRuntime(1172): Caused by: java.lang.NullPointerException**
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android.app.ContextImpl.openFileOutput(ContextImpl.java:601)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android.content.ContextWrapper.openFileOutput(ContextWrapper.java:165)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android_maps_conflict_avoidance.com.google.common.io.android.AndroidPersistentStore.writeBlockX(AndroidPersistentStore.java:140)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android_maps_conflict_avoidance.com.google.common.io.android.AndroidPersistentStore.writeBlock(AndroidPersistentStore.java:169)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android_maps_conflict_avoidance.com.google.common.io.PreferenceStore.ensurePreferencesLoaded(PreferenceStore.java:178)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android_maps_conflict_avoidance.com.google.common.io.PreferenceStore.readPreference(PreferenceStore.java:86)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android_maps_conflict_avoidance.com.google.common.io.BasePersistentStore.readPreference(BasePersistentStore.java:41)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android_maps_conflict_avoidance.com.google.common.StaticUtil.readPreferenceAsDataInput(StaticUtil.java:271)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android_maps_conflict_avoidance.com.google.googlenav.datarequest.DataRequestDispatcher.loadOrRequestCookie(DataRequestDispatcher.java:493)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android_maps_conflict_avoidance.com.google.googlenav.datarequest.DataRequestDispatcher.<init>(DataRequestDispatcher.java:390)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android_maps_conflict_avoidance.com.google.googlenav.datarequest.DataRequestDispatcher.createInstance(DataRequestDispatcher.java:341)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at com.google.android.maps.MapActivity.createMap(MapActivity.java:548)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at com.google.android.maps.MapActivity.onCreate(MapActivity.java:422)
**03-28 09:09:54.744: E/AndroidRuntime(1172):   at m.p.LiveActivity.onCreate(LiveActivity.java:20)**
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android.app.Activity.performCreate(Activity.java:4397)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1048)
03-28 09:09:54.744: E/AndroidRuntime(1172):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1779)
03-28 09:09:54.744: E/AndroidRuntime(1172):     ... 11 more

还有我的manifest.xml

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

    <uses-sdk android:minSdkVersion="8" />

    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />

    <application
        android:icon="@drawable/logo_hg_03"
        android:label="@string/app_name"
        android:theme="@android:style/Theme.NoTitleBar" >
        <uses-library android:name="com.google.android.maps" />

        <activity
            android:name=".SteuerungActivity"
            android:label="@string/app_name"
            android:screenOrientation="landscape" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".LiveActivity" />
        <activity android:name=".DataActivity" />
    </application>

亲爱的未来读者： 我还没有找到这个错误的原因，但我就是这样解决这个问题的： 1我删除了avd 2我重新安装了sdk版本

---

3i根据MapActivity的文档创建了一个新的avd：

这里我们初始化静态工厂，创建映射对象和 流量服务，但不启动任何线程。子类应该 通过调用创建或膨胀其MapView对象 super.onCreate

---

这意味着映射活动也会对bundle执行一些逻辑。它显然在某些状态下失败。我不完全相信这与传递的包有关。我希望我能在stacktrace中看到android\u maps\u conflict\u Avoidation.com.google.common.io.android.AndroidPersistentStore或其他东西的代码。

我以前从未见过这个错误。从我看来，你的代码似乎很好。你在测试什么？我用模拟器3.2谷歌API测试这个，看起来我不是第一个出现这个错误的人。。。其他人似乎有这个问题。。。但据我所知，谷歌翻译给了我什么，这是没有解决的…如果你能创建一个示例项目来演示这个错误，把源代码发布到某个地方-我会有兴趣看看它。@commonwave

package m.p;


import com.google.android.maps.MapActivity;
import com.google.android.maps.MapView;

import m.p.R;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ListView;

public class LiveActivity extends MapActivity  {
    @Override
    public void onCreate(Bundle savedInstanceState) { //line 19
        super.onCreate(savedInstanceState); //line 20
        setContentView(R.layout.live); //line 21

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

    <uses-sdk android:minSdkVersion="8" />

    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="android.permission.INTERNET" />

    <application
        android:icon="@drawable/logo_hg_03"
        android:label="@string/app_name"
        android:theme="@android:style/Theme.NoTitleBar" >
        <uses-library android:name="com.google.android.maps" />

        <activity
            android:name=".SteuerungActivity"
            android:label="@string/app_name"
            android:screenOrientation="landscape" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".LiveActivity" />
        <activity android:name=".DataActivity" />
    </application>