Unable to instantiate activity component when running android example code

Question

I am learning the tutorial from the android web site.

But when I run the application, it prompts Unable to instantiate activity component, something about the classNotFoundException. But in the manifext.xml file the MainActivity was registered. I don't know where is the problem. Here is the full error log.

05-03 18:59:00.425: E/AndroidRuntime(20858): FATAL EXCEPTION: main
05-03 18:59:00.425: E/AndroidRuntime(20858): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.android.effectivenavigation/com.example.android.effectivenavigation.MainActivity}: java.lang.ClassNotFoundException: com.example.android.effectivenavigation.MainActivity
05-03 18:59:00.425: E/AndroidRuntime(20858):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1983)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at android.app.ActivityThread.access$600(ActivityThread.java:130)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at android.os.Handler.dispatchMessage(Handler.java:99)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at android.os.Looper.loop(Looper.java:137)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at android.app.ActivityThread.main(ActivityThread.java:4745)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at java.lang.reflect.Method.invokeNative(Native Method)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at java.lang.reflect.Method.invoke(Method.java:511)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at dalvik.system.NativeStart.main(Native Method)
05-03 18:59:00.425: E/AndroidRuntime(20858): Caused by: java.lang.ClassNotFoundException: com.example.android.effectivenavigation.MainActivity
05-03 18:59:00.425: E/AndroidRuntime(20858):    at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:61)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at java.lang.ClassLoader.loadClass(ClassLoader.java:501)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at java.lang.ClassLoader.loadClass(ClassLoader.java:461)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at android.app.Instrumentation.newActivity(Instrumentation.java:1053)
05-03 18:59:00.425: E/AndroidRuntime(20858):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1974)
05-03 18:59:00.425: E/AndroidRuntime(20858):    ... 11 more

manifest file, AbdroidManifest.xml

<!--
  Copyright 2012 The Android Open Source Project

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.
  -->

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.android.effectivenavigation"
    android:versionCode="1"
    android:versionName="1.0">

    <uses-sdk android:minSdkVersion="14" />

    <application android:label="@string/app_name"
        android:icon="@drawable/ic_launcher"
        android:theme="@android:style/Theme.Holo.Light.DarkActionBar">

        <activity android:name=".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>

        <activity android:name=".CollectionDemoActivity" android:label="@string/demo_collection" />

    </application>
</manifest>

Answer 1

If I'm not mistaken you are using Android Support Library. How did you add it to your project? If you added in Java Build Path you might face this exception.

A suggestion would be to remove the JAR from your build path and just right click on your project and choose Android Tools --> Add Support Library.