Develop Reference

Open Apps Widgets screen Android

How to open the Apps | Widget screen?
I mean this screen

Got the issue, basically all you have to do is make an intent that chooses this.
Intent homeScreenIntent = new Intent(Intent.ACTION_MAIN);
homeScreenIntent.addCategory(Intent.CATEGORY_LAUNCHER);
homeScreenIntent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(homeScreenIntent);
Hope it helps.
Won't recommend but seems one of this will work but be careful:
moveTaskToBack(true) // Pushes the activity in stack to back.
and
finish() // Kills the app
Reference: Dev blog

Start Google Navigation from another Activity without setting a location

This is probably really stupid of me but how do I start google navigation WITHOUT setting a location as a lot of issues seem to come from... When I try to do this it actually starts to run Google Navigation but then just keeps restarting the Activity... Essentially I was it to run just like when you click on Navigation like you would from a home screen... So with the list of destinations etc... I presume this is a different activity maybe? I've no idea, the intent I'm using is below,
Intent i = new Intent(Intent.ACTION_VIEW);
i.setClassName("com.google.android.apps.maps", "com.google.android.maps.driveabout.app.NavigationActivity");
getContext().startActivity(i);

Finally found what Activity it is that needs starting!!!
Intent i = new Intent();
i.setClassName("com.google.android.apps.maps","com.google.android.maps.driveabout.app.DestinationActivity");
startActivity(i);

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

Android: Starting An Activity For A Different Third Party App

I'm working on an app and I want to integrate the Last.fm app into it. Basically, when someone is looking at an artist in my app, I would like to have a button that they can tap to open up Last.fm application with the artist's information.
This intent works, but it loads a menu asking which app I would like to use (Browser or Last.fm):
Intent i = new Intent();
i.setData(Uri.parse("http://last.fm/music/" + headliner));
i.setAction("android.intent.action.VIEW");
startActivity(i);
However, I just want to start the Last.fm app and skip the dialog asking which app to use, I thought maybe using the setPackage() method would work like this:
i.setPackage("fm.last.android");
But it causes the app to crash:
android.content.ActivityNotFoundException: No Activity found to handle Intent { act=android.intent.action.VIEW dat=http://last.fm/music/Rihanna pkg=fm.last.android }
Is it possible to just start the Last.fm app? Here's a copy of Last.fm's AndroidManifest.xml for reference.
Thanks for reading,
Tony

Yes, it's possible but you need to know the correct component name. Launch the last.fm app regularly and check the logfile for the cmp=... information that's been used when the app is started. Use this as well in your app then.
I start the Z-DeviceTest app from the market from within my app without a problem like this:
final Intent intentDeviceTest = new Intent("android.intent.action.MAIN");
intentDeviceTest.setComponent(new ComponentName("zausan.zdevicetest","zausan.zdevicetest.zdevicetest"));
startActivity(intentDeviceTest);
in my case the info I took from the logcat was:
// dat=content://applications/applications/zausan.zdevicetest/zausan.zdevicetest.zdevicetest
// cmp=zausan.zdevicetest/.zdevicetest
in order to know how to start the app with the right component/class... do the same for the last.fm app
Edit:
I've tested to launch Last.fm from my own app, and this works fine without any errors:
final Intent intentDeviceTest = new Intent("android.intent.action.MAIN");
intentDeviceTest.setComponent(new ComponentName("fm.last.android","fm.last.android.LastFm"));
startActivity(intentDeviceTest);

Opening browser activity, but prevent it from being in the activity history

I'm working on an app that launches the browser activity to perform a Twitter OAuth authorization. This process uses a callback url which will re-launch the activity that started the browser activity in the first place.
My problem is that the browser pages remain in the history stack and when the user then clicks back from the preferences activity that launched the browser in the first place, they don't go back to the app's main activity, but instead are brought back to the browser. I've tried adding flags to the launching intent to prevent history and reset on clear, but it doesn't seem to work when running on my phone, only on the emulators.
Here is the code I'm using to launch the browser activity:
Intent webIntent = new Intent(Intent.ACTION_VIEW, Uri.parse(authUrl));
webIntent.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
webIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_WHEN_TASK_RESET);
webIntent.addFlags(Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);
ctx.startActivity(webIntent);
Anyone have any idea what might be wrong?

Set the activity flag to Intent.FLAG_ACTIVITY_CLEAR_TOP after starting it. This way, the task will be deleted form the app stack so your main activity remains the top one on every new launch:
ctx.startActivity(webIntent);
browserIntent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

call
finish();
after
ctx.startActivity(webIntent);

Hi i have the same problem at the moment. I think the solution is to start the activity you want to return to with a special flag:
Intent intent = new Intent(this, acticityToReturnTo.getClass());
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
intent.setFlags(Intent.FLAG_ACTIVITY_SINGLE_TOP);
startActivity(intent);
The problem is that is does not work (on 1.6 at least).. But maybe someone finds a solution for this. I think FLAG_ACTIVITY_CLEAR_TOP is exactly what we.

I found that Intent.FLAG_ACTIVITY_NO_HISTORY works only if the browser was not running before. If I restart Android and run my app which call browser everything work well. But when I start browser before my app, browser will stay in history.
Here is related question also, but with no really working solution
How can I do that in Android. Activity -> WebBrowser -> Acrivity, but Press Back not see the WebBrowser