Develop Reference

Calling an Application Activity from a Library Project in Android

Ok,
So I'm making a library project of UI elements. The Library has some activities which are based of ActionBarSherlock which is a backwards compatibility library for the action bar in android. In these activities I would like to have a button in the action bar which will take the user home regardless of which activity they are using in the Library project.
Some terminology. The 'library' refers to the Android UI library project I'm working on. The 'Application' refers to whatever customer a developer might be using with the Library included.
Usually, when you make an activity and you want to call another, you would do something like this.
intent = new Intent(this, WhateverMyActivityName.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
Simple enough. But here's the tricky bit. Android Libraries have little to no knowledge of what application is using them. So 'WhateverMyActivityName.class' is useless as there is no way to predict what the developers application will call their activities.
I need to replace
intent = new Intent(this, WhateverMyActivityName.class);
with something like this
intent = new Intent(this, getApplication().MainActivity().getClass());
or possibly use some sort of intent action which will call the main Activity in the application (Intent.ACTION_MAIN or Intent.CATEGORY_LAUNCHER)
So in short: How do I get an applications main activity from a library project?

We can use reflection to get class object.
Class.forName("com.mypackage.myMainActivity")
Add this code in Library project to call,
try {
Intent myIntent = new Intent(this,Class.forName("com.mypackage.myMainActivity"));
startActivity(myIntent );
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
"com.mypackage.myMainActivity" is the Activity present in Main project, that we need to call from its Library project.

The application calls some method in your library providing the Intent to be invoked, or providing the Class of the activity to be invoked. Your library stores that someplace and uses it.
Your assumption that the right answer is "Intent.ACTION_MAIN or Intent.CATEGORY_LAUNCHER" may be inaccurate. For example, some apps have that be a splash screen activity (which is an issue in its own right, but that's beside the point), and that would not be where a home affordance within the app should go.

You can get the list of activities using the code mentioned in the this post. After that loop through the resolveinfo and check the intenet filter to find the activity with your desired intent action.

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

Problem launching Google Navigation

i tried since many hours to launch navigation from my app.
I want navigation without destination.
i tried with
Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse("google.navigation:q="));
startActivity(i);
That launches navigation but with destination not found
I tried too to launch processName, packageName with startIntent with com.google.android.apps.maps,
com.google.android.apps.maps:driveabout and
**com.google.android.maps.driveabout.app.DestinationActivity
with no succes too :/
an idea ?

Google Navigation does not have any documented and supported Intent filters. It is not designed to be integrated from third party apps.

The following code should work...
String url = "google.navigation:q="+startPos.getLatitude()+","+startPos.getLongitude();
Intent i = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
startActivity(i);

Take a closer look a the intent filter for Google Navigation. It could be that it is not designed to be started via Intent without a specified destination. Unfortunately, i don't know where to find information about Google Navigation's intent filter, but if you were to show me where you are looking i could help you figure it out.

Try using
google.navigation:fd=true

i don't want to integrate it, i just want to launch it like a click on the list of apps whith a home launcher.
I've tried the google home sample, and navigation can be launched.
but i don't understand why that doesn't work with my own app :/

2 Intent Filters, 1 Activity - Which opened it?

Is there a way to know which Intent Filter is responsible for launching an Activity which has two Intent Filters defined in AndroidManifest.xml? I want a slightly different set of logic, but not enough that should require a whole new Activity.
Thanks!

Never mind, found it. Just wasn't looking hard enough...
Using this.getIntent().getAction() in your Activity will spit out exactly what I was looking for, a String to identify which Intent Filter Action opened it.

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.