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How do I launch a specific (explicit) activity of another app

I want to launch a specific activity of another app from my app. For example, on the onCreate of my app, I want to launch the activity named Rolling (not main) activity of com.pas.webcam.pro. I have heard that you must have control of both apps to do this because you must add an intent filter to the manifest of the second app. This is not true though, because activity launcher apps in the Google Play Store can launch the Rolling Activity of IP Webcam Pro.
The Activity Launcher app is open source, so I tried reviewing the source code here. It was too complicated though, so I could not figure out how this app magically launches this activity. There are many other questions like this on Stack Overflow, and I have read every one. I have also tried lots of the code from the answers too, like this:
Intent intent = new Intent(); intent.setComponent(new ComponentName("com.pas.webcam", "com.pas.webcam.RollingActivity")); startActivity(intent);
I have also tried variants of this code from other posts. My app always crashes and I get variants (depending on the code I use) of the following error:
An error occurred
Invalid intent operation. Unable to find explicit activity class {com.pas.webcam.pro/com.pas.webcam.pro.Rolling}; have you declared this activity in your AndroidManifest.xml?
I have put both of the following in my Android Manifest and the same thing happens:
<uses-permission android:name="android.permission.GET_INSTALLED_PACKAGES" />
<activity android:name="com.pas.webcam.pro.RollingActivity"
Thanks in advance for any answers, I really appreciate it, as I have been working on this problem for a while.
Edit: Here is the activity of the app I want to launch: https://i.stack.imgur.com/Fa7Xq.jpg
Edit: David Wasser helped me solve the problem by giving me the code neccessary to solve the problem. It actually works! To anyone who wants to launch a specific activity of another app with code, please use this:
Intent intent = new Intent(); intent.setClassName("com.pas.webcam.pro", "com.pas.webcam.Rolling"); startActivity(intent);
You may replace com.pas.webcam.pro and Rolling with the app and activity of your choice, but this method truly works. Problem Solved!😀

Try this:
Intent intent = new Intent();
intent.setClassName("com.pas.webcam.pro", "com.pas.webcam.Rolling");
startActivity(intent);
Since you refer to the app as "IP webcam pro", I'm assuming the package name is "com.pas.webcam.pro" (found by Internet research).

Closing settings programmatically

I need some help , I tram trying to close android settings, (com.android.settings (packageName)), but I can't find how can it be done, I am testing in android O , please suggest something , I tried to kill process but it did'nt work too ..
how can it be done ? )

You can use FLAG_ACTIVITY_CLEAR_TOP, you can read more about it in docs
If set, and the activity being launched is already running in the current task, then instead of launching a new instance of that activity, all of the other activities on top of it will be closed and this Intent will be delivered to the (now on top) old activity as a new Intent.
Here is an example
Intent i = new Intent(this, YOUR_ACTIVIRTY.class);
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);

Refresh running activity with new data from AsyncTask result

I have a class, that executes some command in background. Class method is executed asynchronously (by using AsyncTask) and when command finishes, it posts event with command result. Then, new activity is started. To do this, I added inside OnCreate method to MainActitity:
ssh = new SshSupport();
ssh.Connect();
ssh.ExecuteCommand(commandType);
//..................................
ssh.eventHandler = new ISshEvents()
{
#Override
public void SshCommandExecuted(SshCommandsEnum commandType, String result)
{
if (progressDialogExecuting.isShowing()) progressDialogExecuting.dismiss();
Intent intent = new Intent(MainActivity.this, ResultListActivity.class);
intent.putExtra("result", result);
intent.putExtra("commandType", commandType);
startActivity(intent);
}
So it works as should. My commands starts in background and when finished, my event fires and displays new activity with results (all results are received via getIntent().getExtras() and then formatted to be displayed as should).
Problem: on result activity I have "Refresh" button. When pressed, all data should be refreshed. So I need to execute ssh.ExecuteCommand(commandType); again to get refreshed data. Note that I don't want to open new ssh connection for this. Instead, I want to use already opened connection and simply execute my command again.
So I made my 'ssh' static and I used MainActivity.ssh.ExecuteCommand(commandType); on refresh button press. It works, but obviously, it causes to create second instance of ResultListActivity, instead of refreshing data on existing one.
I can even avoid to creating result activity again by checking if it's already exists (for example by adding 'active' boolean static variable to it). However, it won't help me because I still have no any possibility to refresh data inside my existing activity.
So, how can I do it?

No responses, so I'm answering to my own question. My solution was:
- Change my activity launchMode to singleTop
- Override method onNewIntent
In this case each time I start this activity: if activity already exists it won't be created again. Instead, onNewIntent method will be called.
http://developer.android.com/guide/topics/manifest/activity-element.html#lmode
http://developer.android.com/reference/android/app/Activity.html#onNewIntent%28android.content.Intent%29
However, I'm not sure if approach like this is good. How do you think?

Android java trouble with start new activity

In MainActivity starts another activity via startActivityForResult
Intent intent = new Intent(MainActivity.this, AutorisationForm.class);
intent.putExtra("req", 1);
startActivityForResult(intent, 0);
Method onCreate executes successful, activity displays on the screen and then app crash. Eclipse returns "source not found" error.
How I can solve this problem?
P.S. All activities declared in manifest.
P.P.S All worked successfully before I add a lot of logic in MainActivity. This code and second class hasn't changed.

Problem solved. Mistake was in onDestroy() method in MainActivity. In this method app try to save unloaded file. Theme closed.

Undo all changes before adding "a lot of logic in MainActivity."
Add changes one at a time and test in between until you discover problem.
Problem discovered!

Android - instead of launch new intent to new class/activity, how go back to open activity/class?

My code allows me to launch a new activity/class:
Intent intent = new Intent(activity1.this, activity2.class);
startActivity(intent);
finish();
What if i have an activity already open, and just want to go back to it instead of reopening a new one, thus having multiple open of same.. So i want to switch back to an already open activity/class ?

Intent intent = new Intent(activity1.this, activity2.class);
intent .setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
startActivity(intent);

It's the same thing. Android OS doesn't create 2 different versions of your activity, it works with already created activities.

Really simple:
finish();
If you want to choose an already existing activity in the backstack and not simply the latest opened that will be more complex and I don't know if you can modify the normal application workflow

Add this
FLAG_ACTIVITY_REORDER_TO_FRONT to your Intent you use with startActivity() .
Also remove finish()

If I'm getting you right, you need to use Intent.FLAG_ACTIVITY_REORDER_TO_FRONT flag. In this case your activity, if it was created before, will be brought to the front. As documentation states,
If set in an Intent passed to Context.startActivity(),
this flag will cause the launched activity to be brought
to the front of its task's history stack if it is already running.