找不到启动程序活动！在android中

我有一个android应用程序，其中我使用manifest.xml文件中的google maps设置。当我在eclipse中运行应用程序时，输出如下

[2015-02-25 17:59:06 - MainActivity] ------------------------------
[2015-02-25 17:59:06 - MainActivity] Android Launch!
[2015-02-25 17:59:06 - MainActivity] adb is running normally.
[2015-02-25 17:59:06 - MainActivity] No Launcher activity found!
[2015-02-25 17:59:06 - MainActivity] The launch will only sync the application package on the device!
[2015-02-25 17:59:06 - MainActivity] Performing sync
[2015-02-25 17:59:06 - MainActivity] Automatic Target Mode: using existing emulator 'emulator-5554' running compatible AVD 'Nexus7'
[2015-02-25 17:59:06 - MainActivity] Uploading MainActivity.apk onto device 'emulator-5554'
[2015-02-25 17:59:07 - MainActivity] Installing MainActivity.apk...
[2015-02-25 17:59:19 - MainActivity] Success!
[2015-02-25 17:59:19 - appcompat_v7] Could not find appcompat_v7.apk!
[2015-02-25 17:59:19 - MainActivity] /MainActivity/bin/MainActivity.apk installed on device
[2015-02-25 17:59:19 - MainActivity] Done!

该应用程序安装在emulatorandroid 4.2.2 API级别19上，但当我试图打开它时，它崩溃了，因为我说不幸的是，你的应用程序已关闭，我在logcat中发现以下错误

02-25 07:37:30.540: E/AndroidRuntime(2194): FATAL EXCEPTION: main
02-25 07:37:30.540: E/AndroidRuntime(2194): Process: com.example.project, PID: 2194
02-25 07:37:30.540: E/AndroidRuntime(2194): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.project/com.example.project.MainActivity}: java.lang.ClassNotFoundException: Didn't find class "com.example.project.MainActivity" on path: DexPathList[[zip file "/system/framework/com.google.android.maps.jar", zip file "/data/app/com.example.project-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.example.project-1, /vendor/lib, /system/lib]]
02-25 07:37:30.540: E/AndroidRuntime(2194):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2121)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at android.os.Handler.dispatchMessage(Handler.java:102)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at android.os.Looper.loop(Looper.java:136)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at android.app.ActivityThread.main(ActivityThread.java:5017)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at java.lang.reflect.Method.invokeNative(Native Method)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at java.lang.reflect.Method.invoke(Method.java:515)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at dalvik.system.NativeStart.main(Native Method)
02-25 07:37:30.540: E/AndroidRuntime(2194): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.example.project.MainActivity" on path: DexPathList[[zip file "/system/framework/com.google.android.maps.jar", zip file "/data/app/com.example.project-1.apk"],nativeLibraryDirectories=[/data/app-lib/com.example.project-1, /vendor/lib, /system/lib]]
02-25 07:37:30.540: E/AndroidRuntime(2194):     at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
02-25 07:37:30.540: E/AndroidRuntime(2194):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2112)
02-25 07:37:30.540: E/AndroidRuntime(2194):     ... 11 more
02-25 07:37:36.350: I/Process(2194): Sending signal. PID: 2194 SIG: 9

下面是代码文件

AndroidManifest.xml

main.xml

因此，从上面看，我觉得所有配置都是正确的，但为什么我仍然找不到MainActivity类？

修改如下：

<activity android:name="MainActivity"
                  android:label="@string/app_name"
                  android:screenOrientation="portrait">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
                <action android:name="com.google.android.c2dm.intent.REGISTRATION" />
                <action android:name="com.google.android.c2dm.intent.RECEIVE" />
            </intent-filter>
        </activity>

到

---

只需将该活动与软件包名称一起提及

只需在活动名称前添加一个点，即更改为.MainActivity而不是activity，因为android在与软件包名称相关后无法找到它

<activity android:name=".MainActivity"
                  android:label="@string/app_name"
                  android:screenOrientation="portrait">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
                <action android:name="com.google.android.c2dm.intent.REGISTRATION" />
                <action android:name="com.google.android.c2dm.intent.RECEIVE" />
            </intent-filter>
        </activity>

---

如上所述更改此标记。

@NoName yeah尝试使用点和完整包名，但仍然得到相同的错误。您是指整个MainActivity代码吗？您可以添加目标sdk吗？尝试更改包名并重新安装。@Droidkas yeah添加并检查了它，但结果是相同的，确实无法找出这里的问题所在

<android.support.v4.view.ViewPager xmlns:android="http://schemas.android.com/apk/res/android"
                                   android:id="@+id/pager"
                                   android:layout_width="match_parent"
                                   android:layout_height="match_parent"/>

<activity android:name="MainActivity"
                  android:label="@string/app_name"
                  android:screenOrientation="portrait">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
                <action android:name="com.google.android.c2dm.intent.REGISTRATION" />
                <action android:name="com.google.android.c2dm.intent.RECEIVE" />
            </intent-filter>
        </activity>

<activity android:name="com.example.project.MainActivity"
                  android:label="@string/app_name"
                  android:screenOrientation="portrait">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
                <action android:name="com.google.android.c2dm.intent.REGISTRATION" />
                <action android:name="com.google.android.c2dm.intent.RECEIVE" />
            </intent-filter>
        </activity>

<activity android:name=".MainActivity"
                  android:label="@string/app_name"
                  android:screenOrientation="portrait">
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
                <action android:name="com.google.android.c2dm.intent.REGISTRATION" />
                <action android:name="com.google.android.c2dm.intent.RECEIVE" />
            </intent-filter>
        </activity>

<activity android:name="com.example.project.MainActivity"
              android:label="@string/app_name"
              android:screenOrientation="portrait">
        <intent-filter>
            <action android:name="android.intent.action.MAIN"/>
            <category android:name="android.intent.category.LAUNCHER"/>
            <action android:name="com.google.android.c2dm.intent.REGISTRATION" />
            <action android:name="com.google.android.c2dm.intent.RECEIVE" />
        </intent-filter>
    </activity>