java.lang.RuntimeException: Unable to instantiate activity ComponentInfo/ ClassNotFoundException

Question

I'm develop android application and than i wanna additional new Activity i had error on my logcat

My LogCat:

04-19 12:59:17.654: D/AndroidRuntime(18135): Shutting down VM
04-19 12:59:17.654: W/dalvikvm(18135): threadid=1: thread exiting with uncaught exception (group=0x4001d878)
04-19 12:59:17.684: E/AndroidRuntime(18135): FATAL EXCEPTION: main
04-19 12:59:17.684: E/AndroidRuntime(18135): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.bvblogic.android.batterypower/com.bvblogic.android.batterypower.activities.UnlockActivity}: java.lang.ClassNotFoundException: com.bvblogic.android.batterypower.activities.UnlockActivity in loader dalvik.system.PathClassLoader[/data/app/com.bvblogic.android.batterypower-1.apk]
04-19 12:59:17.684: E/AndroidRuntime(18135):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2587)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2681)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at android.app.ActivityThread.access$2300(ActivityThread.java:125)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at android.os.Handler.dispatchMessage(Handler.java:99)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at android.os.Looper.loop(Looper.java:123)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at android.app.ActivityThread.main(ActivityThread.java:4640)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at java.lang.reflect.Method.invokeNative(Native Method)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at java.lang.reflect.Method.invoke(Method.java:521)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at dalvik.system.NativeStart.main(Native Method)
04-19 12:59:17.684: E/AndroidRuntime(18135): Caused by: java.lang.ClassNotFoundException: com.bvblogic.android.batterypower.activities.UnlockActivity in loader dalvik.system.PathClassLoader[/data/app/com.bvblogic.android.batterypower-1.apk]
04-19 12:59:17.684: E/AndroidRuntime(18135):    at dalvik.system.PathClassLoader.findClass(PathClassLoader.java:243)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at java.lang.ClassLoader.loadClass(ClassLoader.java:573)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at java.lang.ClassLoader.loadClass(ClassLoader.java:532)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at android.app.Instrumentation.newActivity(Instrumentation.java:1021)
04-19 12:59:17.684: E/AndroidRuntime(18135):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2579)
04-19 12:59:17.684: E/AndroidRuntime(18135):    ... 11 more

My manifest.xml

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

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

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.BATTERY_STATS" />
    <uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
    <uses-permission android:name="android.permission.UPDATE_DEVICE_STATS" />
    <uses-permission android:name="android.permission.CHANGE_WIFI_STATE" />
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.BLUETOOTH" />
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
    <uses-permission android:name="android.permission.WRITE_SETTINGS" />
    <uses-permission android:name="android.permission.HARDWARE_TEST" />
    <uses-permission android:name="android.permission.RESTART_PACKAGES" />
    <uses-permission android:name="android.permission.KILL_BACKGROUND_PROCESSES" />
    <uses-permission android:name="android.permission.GET_PACKAGE_SIZE" />
    <uses-permission android:name="android.permission.WAKE_LOCK" />
    <uses-permission android:name="android.permission.READ_PHONE_STATE" />
    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW" />

    <application
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity android:name=".activities.UnlockActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name="com.bvblogic.android.batterypower.activities.BatteryPowerTabActivity" >
        </activity>
        <activity android:name="com.bvblogic.android.batterypower.activities.MonitoringActivity" >
        </activity>
        <activity android:name="com.bvblogic.android.batterypower.activities.SettingsActivity" >
        </activity>
        <activity android:name="com.bvblogic.android.batterypower.activities.ProcessManagerActivity" >
        </activity>
        <activity
            android:name="com.bvblogic.android.batterypower.activities.DummyBrightnessActivity"
            android:excludeFromRecents="true"
            android:taskAffinity="com.bvblogic.android.batterypower.Dummy"
            android:theme="@android:style/Theme.Translucent.NoTitleBar" >
        </activity>

        <service android:name="com.bvblogic.android.batterypower.util.TurboBoost" >
        </service>
        <service android:name="com.bvblogic.android.batterypower.services.BatteryPowerService" />

        <receiver
            android:name="com.bvblogic.android.batterypower.alarm.RegistrationAlarm"
            android:process=":registration" >
        </receiver>
        <receiver
            android:name="com.bvblogic.android.batterypower.alarm.OnlinePingAlarm"
            android:process=":ping" >
        </receiver>
        <receiver
            android:name="com.bvblogic.android.batterypower.alarm.AdNotificationAlarm"
            android:process=":remote" >
        </receiver>
        <receiver
            android:name="com.bvblogic.android.batterypower.widget.MWidgetProvider"
            android:icon="@drawable/btn_remove"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.appwidget.action.APPWIDGET_UPDATE" />
            </intent-filter>

            <meta-data
                android:name="android.appwidget.provider"
                android:resource="@xml/widget_provider" />
        </receiver>
    </application>

</manifest>

My Activity:

package com.bvblogic.android.batterypower.activities;

import com.bvblogic.android.batterypower.R;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class UnlockActivity extends Activity {  
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.settings_auto_saving_layout);
    }
}

Then i'm assigned intent-filter to BatteryPowerTabActivity application started fine. Please help me. Thanks

Answer 1

This can happen if your activity class is inside a default package. I fixed it by moving the activity class to a new package. and changing the manifest.xml

before

activity android:name=".MainActivity"

after

activity android:name="new_package.MainActivity"

Answer 2

I had the same problem, but I had my activity declared in the Manifest file, with the correct name.

My problem was that I didn't have to imported a third party libraries in a "libs" folder, and I needed reference them in my proyect (Right-click, properties, Java Build Path, Libraries, Add Jar...).

About how do you declare an activity in the manifest file, is correct use .ActivityName always that activity be in the main package.