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Android start activity of second app having no icon from first app

I am having two apps. First app has an activity from which I want to launch an activity from the second app. I am using the following code:
Intent launchIntent = m_context.getPackageManager().getLaunchIntentForPackage(m_packageName);
if (launchIntent != null) {
m_context.startActivity(launchIntent);
}
This code is working very fine to launch the activity from the second app but I want to have the second application without any icon. I am using following code in MainActivity of the second application to remove icon:
PackageManager p = getPackageManager();
//Removing app icon
ComponentName componentName = new ComponentName(this, com.tools.html2pdf.MainActivity.class);
p.setComponentEnabledSetting(componentName, PackageManager.COMPONENT_ENABLED_STATE_DISABLED, PackageManager.DONT_KILL_APP);
This code successfully removes the launcher icon but then activity from my first application is unable to launch the activity from second app.
Can any one help me in this regard? I want to launch activity of an app having no icon from activity of another application.

When you disable the component like you have done, that component can't be launched in any way. However, interesting thing is that other components (non-disabled activities) of your second application are still launchable.
So, you can create an alias of your MainActivity in the second application which will be used for your purpose. Let's call alias as MainActivityAlias.
From your first application, call the intent on MainActivity. The code for disabling the component will be executed and nothing will open. However, the icon will be gone because this component is disabled and everything related to this component (i.e icon) is gone too.
Now, call the intent on MainActivityAlias just after above intent in the first application. This is just a copy of MainActivity but it does not have any code for disabling and thus, it is enabled and launchable.
Some Side Notes :
1) Both activities should have an <intent-filter> with android.intent.action.MAIN.
2) Your MainActivity should be the launcher activity and thus should have android.intent.category.LAUNCHER in the manifest.
3) Inside MainActivity, you have to check where the call is coming from. If the call is from the first application, then execute the code to disable icon which you mentioned in the question. If the call is coming from launcher icon, then open MainActivityAlias using intent. You can know where the call is coming from like this.
Note - This is just an idea. I have not tested it.

If you don't want the second app to have an app icon, just remove the <intent-filter> with ACTION=MAIN and CATEGORY=LAUNCHER for the root Activity in the second app. When the app is installed, if there is no <intent-filter> with ACTION=MAIN and CATEGORY=LAUNCHER, there will be no app icon shown.
Your app can still launch the second app, but not with the method you've described, since Android doesn't know which is the "launch" Activity. Assuming you know the package and class name of the Activity you want to launch in the second app, you can launch it like this:
Intent launchIntent = new Intent();
launchIntent.setClassName("second.package.name", "fully.qualified.class.name.of.MainActivity");
// add and Intent flags if necessary here
launchIntent.addFlags(Intent.FLAG_ACTIVITY_...);
startActivity(launchIntent);

Why does the Main activity has an intent filter?

If the intent filters are to resolve implicit intents, then why does
the MainActivity(which is the very first activity that is run when
app is launched) has an intent filter?
Who send an implicit intent to it?
What if the sent implicit intent doesn't have proper data ?

Well, how does the system know which activity is the main activity? It isn't the name- the system doesn't care about the name. Its the activity with the intent filter that says its the main activity.
It can also have other intent filters to launch it any other way you may want. For example, you may have an intent filter to launch it via a deep link.
As for proper data- if launched from the app list or homescreen, it won't have any data. Its on the programmer of the app to make sure that it can do something that makes sense in that case.

It has CATEGORY_LAUNCHER and ACTION_MAIN .
android.intent.action.MAIN means that this activity is the entry point of the application, i.e. when you launch the application, this activity is created.
CATEGORY_LAUNCHER tells that your activity should be displayed in the top-level launcher.
https://developer.android.com/reference/android/content/Intent.html#ACTION_MAIN
Launcher sends implicit intent to it. This is how launcher knows which activity is to be opened on click.
If you send improper data it will not open your activity. For ex:
If you try to start your main activity using implicit intent only in startActivity then it will not start because there is CATEGORY_DEFAULT associated with it. You need to add one more intent_filter to your activity to resolve the intents.

Android - Call Main Class Activity

I would like to go back to the Main Activity at a certain point in my application. I tried calling the Activity in an Intent as usual, however since the Activity name for the main class is called "android.intent.action.MAIN", which is the general name of every application's main activity, a "Complete Action Using:" menu pops up with every possible application on the phone as an option. I do not want this; what I want is that the main activity for my application loads up.
How can I achieve this?
Thank you in advance!

You can also specify a specific Activity to launch like so:
Intent nextActivityIntent = new Intent(this, MyActivity.class);
startActivity(nextActivityIntent);
As per the Intent documentation, the ACTION_MAIN flag is used to specify that you want to launch an application using the application's main entry point. You generally do not use it in your app unless you are trying to open another app.

How to change main activity in Android programmatically

Is it possible to create two entry points to an application in Android, I mean can I switch the main activity programmatically?

Every exported activity is a potential entry point into your app; a foreign app can start any of them with an intent. (An intent-filter comes with an implicit android:export.) You can however only have one entry point that the launcher will respect. To simulate a second launch-point, either
Provide a completely separate app with the purpose of starting one of your exported activities, or
Give your 'launch' activity the sole purpose of immediately starting one or another activity based on some logic (a saved preference, a phase-of-moon calculation, anything).

check this one below
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_LAUNCHER);
intent.setComponent(new ComponentName(packageName,mainActivity));
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
ctx.startActivity(intent);

I think you are talking about launching activity decision based on some events, then you need to add a broadcast receiver, like by clicking on app icon on launcher if you want to start Activity1. then add intent filters to this activity Action_MAIN and ACTION_LAUNCHER, if you want to start Activity2 on phone boot up, then add filter to this activity, BOOT_COMPLETED.

If you are talking about to launch other apps from your apps then this can be the code:
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.addCategory(Intent.CATEGORY_LAUNCHER);
intent.setComponent(new ComponentName(packageName,mainActivity));
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
ctx.startActivity(intent);

Open my application from another in android

My boss asked me to prove that my application behaves properly when summoned by another application (dunno why he asked that).
So I have two apps here, one launches a second one. How I launch the specific app I want? Using Intent launch seemly any generic app that reaches a certain goal, not the app I really want.

Give this a try.
Intent secondIntent = new Intent();
secondIntent.setAction(Intent.ACTION_MAIN);
secondIntent.setClassName("com.example", "com.example.YourSecondApp");
startActivity(secondIntent);
I should point out that com.example should be the package of your second application (the one you want to call) and com.example.YourSecondapp is the class name where you have your onCreate() method.

Intent secondApp = new Intent("com.test.SecondApp");
startActivity(secondApp);
Check out for more examples
http://developer.android.com/resources/faq/commontasks.html#opennewscreen

Create one Intent using the following code
Explicit Intent
When you know the particular component(activity/service) to be loaded
Intent intent = new Intent();
intent.setClass("className/package name");
start<Activity/Service>(intent);
Imlicit Intent
When we do not have the idea which class to load and we know the Action to be perform by the launched application we can go with this intent.
Action needs to set, and the Android run time fallows the intent Resolution technique and list out(one or more components) the components to perform the action. from the list out components (if more than one), user will get the chance to launch his chosen application