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Unable to find explicit activity class, even when i declare the intent in the manifest

I have an activity which I declare in my manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.my">
<uses-sdk android:minSdkVersion="14"/>
<application>
<activity
android:name="com.my.InternalDummyActivity"
android:exported="false">
</activity>
</application>
</manifest>
I have tried without the exported=false as well
The application contains an inner library with another activity.
I try to call an explicit intent from the other activity (other namespace)
But I always get an exception:
Intent intent1 = new Intent(activity.getApplicationContext(), InternalDummyActivity.class);
activity.startActivity(intent1);
ComponentName componentName2 =
new ComponentName(
"com.my","com.my.InternalDummyActivity");
Intent intent2 = new Intent().setComponent(componentName2); //dones work
activity.startActivity(intent2);
Process: com.comp.outter, PID: 9267
android.content.ActivityNotFoundException: Unable to find explicit activity class {com.my/com.my.InternalDummyActivity}; have you declared this activity in your AndroidManifest.xml?
How can I fix this?

Try using one of the ComponentName's contructors that uses a Context, such as
ComponentName cn = new ComponentName(context,
"com.my.InternalDummyActivity");
For some reason, you can use the contructor taking two Strings only if you know the class dynamically.
Also, update your manifest as follow:
<activity
android:name=".InternalDummyActivity">
</activity>
and application package name should be in lower case only, as mentioned in Java's Naming Conventions in Oracle Docs
Package names are written in all lower case to avoid conflict with the
names of classes or interfaces

This question is possible duplicate of the thread gives below
How to call activity from a library module in android studio
Check if this is what you are looking for.

ndroid.content.ActivityNotFoundException:

android.content.ActivityNotFoundException: Unable to find explicit activity class {com.myapp.videomodule/com.myapp.videomodule.VideoCallActivity}; have you declared this activity in your AndroidManifest.xml?
My app package is com.myapp.doctors
module package is com.myapp.videomodule
if(splitInstallManager.getInstalledModules().contains("videomodule")){
Intent intent = new Intent();
intent.setClassName("com.myapp.videomodule", "com.myapp.videomodule.VideoCallActivity");
startActivity(intent);
}
I have declared it in the manifest the thing is I am trying dymanic module delivery, so that videoactivity is in other module

It seems that dynamic feature modules are declared in base app package. (as you can verify using Merged Manifest feature on your module Manifest.xml
I suggest the following modification:
if(splitInstallManager.getInstalledModules().contains("videomodule")){
Intent intent = new Intent();
intent.setClassName(getPackageName(), "com.myapp.videomodule.VideoCallActivity");
startActivity(intent);
}

Go to manifests > AndroidManifest.xml > check if com.myapp.videomodule.VideoCallActivity is declared there, if not, put it like:
<manifest>
....
<application
...>
...
<activity
android:name="com.myapp.videomodule.VideoCallActivity"
android:label="#string/title_videocallactivity" your activity title
android:theme="#style/AppTheme.NoActionBar" />
...
</application>
</manifest>

Try starting the intent like this:
Intent intent = new Intent(this, VideoCallActivity.class);
startActivity(intent)

how to reference classes from other package in Android?

I'd like to ask how to reference other classes from my other package in Android?
I have my main package. Under that it has several subpackages.
How do I reference those classes under subpackage into my main class in the main package?
What I'm doing is, in the main class, I'm calling the class in the subpackage via Intent.
Here's what I've tried so far to no avail:
case 0:
Intent acorn = new Intent( "com.fps.iHealthFirst.vegetables.AcornSquash.class" );
//Intent acorn = new Intent( Nutritional_List.this, AcornSquash.class );
startActivity( acorn );
break;
I'm having a hard time doing this. Thanks for your help.
BTW, this is the logcat:
10-22 23:13:03.585: E/AndroidRuntime(395): FATAL EXCEPTION: main
10-22 23:13:03.585: E/AndroidRuntime(395): android.content.ActivityNotFoundException: Unable to find explicit activity class {com.fps.iHealthFirst/com.fps.iHealthFirst.vegetables.AcornSquash}; have you declared this activity in your AndroidManifest.xml?
Also, I've edited this in the manifest file:
<activity android:exported="false"
android:name=".vegetables.AcornSquashAcornSquash"
android:label="#string/inutrition" >
<intent-filter >
<action android:name="com.fps.iHealthFirst.vegetables.ACORNSQUASH" />
</intent-filter>
</activity>

Here is what you should do:
import com.fps.iHealthFirst.vegetables.AcornSquash;
Intent acorn = new Intent(this, AcornSquash.class);
startActivity(acorn);
UPDATE:
You have to declare all your activities in your Manifest.xml. Keep it simple:
<activity
android:name="com.fps.iHealthFirst.vegetables.AcornSquash"
android:label="#string/some_name" >
</activity>
Finally, make sure your folder structure is in line with your packages paths, i.e. your file AcornSquash.java has to be in the src/com/fps/iHealthFirst/vegetables/ folder.

you can try this:
Intent acorn = new Intent(Intent.ACTION_VIEW, "com.fps.iHealthFirst.vegetables.AcornSquash" );

Using an Android library project Activity within another project

I have an Android library project that I would like to use from within another Android project.
The library has a Activity declared in its AndroidManifest. When I try the following within the second project:
Intent intent = new Intent(this, ReaderActivity.class);
startActivity(intent);
I get the following exception:
java.lang.RuntimeException: Unable to start activity ComponentInfo{br.com.digitalpages.reader.demo/br.com.digitalpages.reader.demo.ReaderDemoActivity}: android.content.ActivityNotFoundException: Unable to find explicit activity class {br.com.digitalpages.reader.demo/br.com.digitalpages.reader.ReaderActivity}; have you declared this activity in your AndroidManifest.xml?
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
...
Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {br.com.digitalpages.reader.demo/br.com.digitalpages.reader.ReaderActivity}; have you declared this activity in your AndroidManifest.xml?
at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1404)
at android.app.Instrumentation.execStartActivity(Instrumentation.java:1378)
...
How can I open the Activity from the another project?
EDIT:
By users answers I added the following line into my second project
<uses-library android:name="br.com.digitalpages.reader" android:required="true" />
But it's still doesn't works

I believe you must include the <activity> in your own AndroidManifest.xml -- I don't think it gets picked up from a library. I don't have my reference for that handy.
Update: It's official solution. From the doc:
Declaring library components in the manifest file
In the manifest file of the application project, you must add
declarations of all components that the application will use that are
imported from a library project. For example, you must declare any
<activity>, <service>, <receiver>, <provider>, and so on, as well as
<permission>, <uses-library>, and similar elements.
Declarations should reference the library components by their
fully-qualified package names, where appropriate.

Intent intent = new Intent(android.content.Intent.ACTION_VIEW);
intent.setComponent(new ComponentName("packagename//ex-com.hello",
"classname//ex-com.hello.ExampleActivity"));
startActivity(intent);
And make sure in library you have declared the activities. You don't need to declare the library activities in your current project's manifest.

did you add to the manifest?
http://developer.android.com/guide/topics/manifest/uses-library-element.html

This works:
In your library, put your custom Activity:
public class MyLibraryActivity extends ListActivity { ... }
No need to put it into a manifest.
In your calling Android project, create an empty (dummy) wrapper:
public class MyActivity extends MyLibraryActivity { }
and add reference to this class to your manifest:
<activity android:name="my_package.MyActivity" ... />

I am aware that the question is quite old but I think this might help people like me that came up with the same problem.
Using Eclipse, the best way to share code and activities among libraries is probably the one that can be found in the android documentation here:
Managing Projects from Eclipse with ADT

When using an activity inside the library, the activity should be declared only inside the manifest of library.
The activity can be started from the main app like this:
Intent intent = new Intent();
intent.setClassName(this, "com.duna.remotelocklibrary.activities.MainRemoteActivity");
startActivity(intent);
I tried to start the library's activity like the following code, but i warn you: it doesn't work
Intent intent = new Intent();
intent.setClassName("com.duna.remotelocklibrary", "com.duna.remotelocklibrary.activities.MainRemoteActivity");
startActivity(intent);

you should import just the code of the activity ( not the manifest too ) , and then , declare your Activity ( of the library ) , in the manifest of your second project

You don't need to explicitly add activity in your main project's manifest if you have already added the activity in your library's manifest by using the following code when starting library's activity.
For Kotlin
val myIntent = Intent(activityContext, ActivityToLaunch::class.java)
// Needed to set component to remove explicit activity entry in application's manifest
myIntent.component = ComponentName(activityContext, PickerActivity::class.java)
activityContext.startActivity(myIntent, PICKER_REQUEST_CODE)
For Java
Intent myIntent = new Intent(activityContext, PickerActivity.class);
// Needed to set component to remove explicit activity entry in application's manifest
final ComponentName component = new ComponentName(activityContext, PickerActivity.class);
myIntent.setComponent(component);
activityContext.startActivity(myIntent, REQUEST_CODE);

How to link two activities in Android project

I just want to code for splashscreen. for that I used intent but I am getting error that instrumention source not found. I have two files splashscreen.java and myapps.java where I have use threading concept and called anothe activity as
finally
{
finish();
startActivity(new Intent("com.example.MyApps"));
stop();
}
# startAcitivy I am getting axception please guide me do I have to modify androidmanifest file? if yes please provide me syntax for that.

If you're starting a new Activity with intent, I prefer using it like:
Intent intent = new Intent(MyClass.this, MyApps.class);
startActivity(intent);
and have proper entry on your manifest for your MyApps class like:
<application>
.......
.....
<activity android:name="com.example.MyApps" />
........
</application>

Add
<activity android:name="com.example.MyApps"></activity>
in your manifest.