Develop Reference

Android Start VPNClient (com.ipsec.vpnclient) Programmatically

I have an android application that requires VPN. My users will be using Galaxy Note 3's and will be using the built in "VPN Client" (com.ipsec.vpnclient). I need to find a way to launch this application from my application, in the instance of the VPN dropping. I've already figured out a way to determine if the VPN dropped, but I still need a way to launch the application.
ANSWER:
Thanks to help from #Muthu I was able to get it working with the following method.
final Intent intent = new Intent("android.intent.action.VIEW");
intent.setComponent(new ComponentName("com.ipsec.vpnclient", "com.ipsec.vpnclient.MainActivity"));
EDIT:
To add to the confusion, I am easily able to add a shortcut to the activity (com.ipsec.vpnclient.MainActivity) via another Launcher like ADW or Nova. I also tried using com.ipsec.vpnclient.MainActivity instead of com.ipsec.vpnclient in the method below, to no avail.
Intent intent = getPackageManager().getLaunchIntentForPackage("com.ipsec.vpnclient");
intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
The above method works with other packages, but I can't seem to get this one to launch.
Here is the application when viewed in Android System Info.
Any ideas on how to launch this application programmatically?

You can Start any installed application by using intent. in your case like this
Intent LaunchVPN = getPackageManager().getLaunchIntentForPackage("com.ipsec.vpnclient");
startActivity( LaunchVPN );
Edit
You can open pre installed apps that can be found inside settings page by
final Intent i = new Intent("android.intent.action.VIEW");
i.setComponent(new ComponentName("com.android.settings","com.android.settings.InstalledAppDetails"));
startActivity(i);

Start multilple activity from broadcastReceiver

I want to start multiple activities from my broadcast receiver. I have two classes i.e ReadContacts and CallDetails. I want to start them one by one. like first calldetails activity should be started and then next. I have tried below code and it works fine.
Intent calldetails = new Intent();
calldetails.setClassName("com.simplereader", "com.simplereader.Calldetails");
calldetails.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
context.startActivity(calldetails);
then I tried below code to start other activity
Intent readcontacts = new Intent();
readcontacts.setClassName("com.simplereader", "com.simplereader.ReadContacts");
calldetails.setFlags(Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
context.startActivity(readcontacts);
But its not working and application crashes.

You must have the Intent Flag Intent.FLAG_ACTIVITY_NEW_TASK to start an Activity from outside of an Activity context so you need to add that flag to your second Intent.
I don't know if this is your only problem but if that doesn't fix it then post your logcat so we can see the error.
Intent readcontacts = new Intent();
readcontacts.setClassName("com.simplereader", "com.simplereader.ReadContacts");
calldetails.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK); // you need this flag
context.startActivity(readcontacts);

FLAG_ACTIVITY_MULTIPLE_TASK Do not use this flag unless you are implementing your own top-level application launcher.
From the android developer documentation for intent.
You could probably just launch both activities with the new task flag.

I think you are making mistake in this line
calldetails.setFlags(Intent.FLAG_ACTIVITY_MULTIPLE_TASK)
If you want to start readcontacts activity it shoul be
readcontacts.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
instead of
calldetails.setFlags(Intent.FLAG_ACTIVITY_MULTIPLE_TASK);
I think this is the reason.

Launching activity from another application not displaying the activity, but it is running

I've done a lot of searching for the last day and haven't found anything that seems to match the problem I'm having.
(For reasons I won't go into) the app is divided into two separate apks. Each have activities. Only the "core" apk has a MAIN activity that is launched from the Android Launcher. The "plugin" apk has activities that only exist to be called from the first apk's activities and does not have a Launcher icon.
The issue I'm having is that when I create an intent to launch an activity from the "plugin" apk, it does the "launching new activity" sliding animation but immediately bounces back. But it is actually launching the activity because I'm seeing log statements in logcat coming from the new activity. I'm not getting any exceptions and it seems to be working other than the fact I'm not seeing the activity on the screen.
I've tried creating the intent in both of the following ways:
Intent myIntent = new Intent(Intent.ACTION_VIEW);
myIntent.setClassName("com.test.plugin", "com.test.plugin.PluginActivity");
startActivity(myIntent);
and
Intent myIntent = new Intent();
myIntent.setComponent(new ComponentName("com.test.plugin", "com.test.plugin.PluginActivity"));
startActivity(myIntent);
But both result in the same thing happening as described above.

It bounces back means the plugin activity has some problem in launching.

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

Launching external application from my app

I would like to launch an app the user selects from within my application. However, I'm not sure how I'd go about doing this. I've tried this:
Intent intent = new Intent();
intent.setAction(Contacts.Intents.SHOW_OR_CREATE_CONTACT);
startActivity(intent);
But this seems to throw an error and force close my application. I also tried adding:
<action android:name="Contacts.Intents.SHOW_OR_CREATE_CONTACT"/>
in the AndroidManifest file, but to no avail.
A look at Logcat shows that it's an "IOexception - no such file or directory". A couple of questions arise from this. I read through the Android docs and noticed that the Contact.Intents class is deprecated. However, it's successor, ContactContracts is aimed at API level 5 whereas I'm targeting API level 3. Could this be the problem? Also, I've hardcoded this application into the code. Is there a way to retrieve the intents of any application the user selects so that they can be launched?

You need to pass extra information into the intent to tell Android what you want to show or create. Otherwise Android doesn't know what activity to start and (presumably in your case) throws an ActivityNotFoundException.
For a contact, you use the generic Intent.ACTION_INSERT_OR_EDIT then use the MIME type of an individual contact (Contacts.People.CONTENT_ITEM_TYPE).
For example:
Intent intent = new Intent(Intent.ACTION_INSERT_OR_EDIT);
intent.setType(People.CONTENT_ITEM_TYPE);
intent.putExtra(Contacts.Intents.Insert.PHONE, "+1234567890");
intent.putExtra(Contacts.Intents.Insert.PHONE_TYPE, Contacts.PhonesColumns.TYPE_MOBILE);
That will bring up the contacts app, prompting you to select an existing contact to add the phone number to, or to create a new contact.
You don't need to add anything special to your manifest to start external activities. Only if you were to directly manipulate the contacts ContentProvider would you need to add the appropriate CONTACT permissions to your manifest.

I use this code for that purpose:
Intent intent = new Intent(Intent.ACTION_MAIN);
intent.setClassName("com.android.settings", "com.android.settings.Settings");
startActivity(intent);
This will launch the Settings app, you can use these also:
intent.setClassName("com.android.music", "com.android.music.MediaPlaybackActivityStarter");
intent.setClassName("com.android.contacts", "com.android.contacts.DialtactsContactsEntryActivity");
intent.setClassName("com.android.contacts", "com.android.contacts.DialtactsActivity");
The first starts the default music app, the second the contacts, and the third the dialer.
Hope this helps.

You need to pass in valid arguments to the apps you start. A lot of apps expect the data URI and / or certain extras to be valid.

Please try the following code:
Intent intent = new Intent(Contacts.Intents.SHOW_OR_CREATE_CONTACT);
this.startActivity(intent);
(sorry if there is something wrong on the syntax, I dont have android in this computer)
And remove the action from the manifest. that is not needed.
The action method is used for something else.
For more info, please look at the android site: http://developer.android.com/reference/android/content/Intent.html
Daniel

The activity you are calling should appear not only in the Manifest for its own package, but in the Manifest for the CALLING package, too.