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Change the layout files in the same activity

I am using setContentView(R.layout.main) to switch the views in the same activity. I am calling some asynchronous task and populating the data on the main layout file after that I am changing the view by calling setContentView(R.layout.main) method.
I came to know that we should not use setContentView method multiple times for same activity. Though it is working fine for me.
Can anyone explain why we should not use setContentView method multiple times for the same activity to change the views?
Will it create any memory related exceptions? Could someone please clarify?

I think switching Views is not a good idea, because android platform already have strong framework to handle the transition in between the views and maintaining the state of each view associated with the Activity its always better to stick with the existing framework instead of thinking of some complex implementation that you have to go through to do all these things. If you do not need any of these things to taken care in your application and if only if you have only two or three screen in your entire application you can try switching the views. That even based on how your views are structured if you have complex logic and lot of data needed to create these views this wont be a good way of doing it.One more thing if you are adding more views say functionality to your application the load that need to be handled by the Activity will go high. In this case you will be declaring and initializing all views inside that particular Activity so maintaining all these views instances is heavy. If you want to know more about the Activty and Task kindly refer this link

Well every time you call setContentView() you'll have to find all the layouts again besides that I think you "can" do it. But as discussed here this is ill adviced as it clearly goes against the android guidelines. Also Commonsware have some very important points here one of the most important being that you will be prone to leak memory as you forget to clean up stuff from your views etc. which Android normally would handle for you.
In short you should follow Android guidelines and use Fragments or start a new Activity.

According to the developer docs setContentView(int layoutResID) is used to
Set the activity content from a layout resource. The resource will be inflated, adding all top-level views to the activity.
In best practice this method is used to Inflate your Activity layout on start up. This does not mean that it will cause issues in the future if you keep using this method. To quote a answer in this question
The setContentView on your Activity actually calls the setContentView on the Window used by the activity, which itself does a lot more than just inflating the layout.
I suggest that you find a alternative way to switch layouts like using a ViewPager with Fragments or some other Tabbing approach but in the end it all comes down to what you want to do.
This question might also give you what you're looking for.

Change layouts without affecting background view in an activity

I'm new to android programming and I'm having a little trouble with the following.
I'm trying to make a menu for a game, and I'd like to have an OpenGL view running in the background (with a running demo of the game) and then have the various menu screens change over the top of this; without reloading or affecting the OpenGL view.
At first glance it appears I have a choice of two methods: the first to use separate activities for each screen and then load each individual menu from xml layouts. This obviously reloads a new instance of the OpenGL view per activity. The second option would be to use a single activity and inflate each XML layout on request, leaving the OpenGL view running untouched.
If possible I'd like to use the first method, but as stated all the views end when a new activity is loaded. The second method I think should work - but then I have all the code for the entire menu in a single file. I'm pretty sure I'm missing something.
If anyone can recommend the best approach for this it would be appreciated.
Thanks.
P.S - I guess the desired result is that similar to the Angry Birds menu which has the continually scrolling landscape in the background.

Use Fragments. You can keep one Activity (you'd have to re-initialise openGL for each activity otherwise), and then have different fragments pop up over your openGL stuff.

Opening an activity within a View in Android

I've recently started developing Android Apps, and whilst the model is making more sense the more I look at it, I cannot do something (nor find any reference material on it) which to me seems quite simple.
I have an activity which has five buttons along the bottom, and a blank View taking up the rest of the screen. I want, upon clicking these buttons, for an activity to be opened in (and confined to) this view. I can get a new activity running without incident, but this opens in a new screen.
If anyone can show me an easy way to launch a (sub/child?) activity within a view which is defined in the parent activity's layout xml file - equally, it could be created in the parent activity - you'd really be doing me a favor!

I'd recommend taking a look at TabHost. The tabhost is an Activity itself, and the sub-views are all Actvities as well.
Here is a good tutorial that'll get you going very quickly. There is a more work to create (optional) icons for the tabs (also describe in the tutorial).
Hope this helps.
Edit* You mentioned buttons being at the bottom of the screen. Take a look at this SO Question

You can achieve that by using an ActivityGroup... here is a simple example which shows how to do it using a TabActivity:
http://web.archive.org/web/20100816175634/http://blog.henriklarsentoft.com/2010/07/android-tabactivity-nested-activities/
Of course, you will have to change the code since you are not using TabActivities. Just take a look at the getLocalActivityManager and getDecorView methods that is what you will be using.

Android Activities vs Views

Sorry, I know that this topic has been covered a bit. I've read the related posts and am still a bit confused. I am working on an app that while the prototype will have 3 main screens, it will eventually have dozens. Each screen will present either dynmically changing status or take user input. To visualize, it is required to be laid out similar to how MS Word or a typical PC is. It has a status bar at the top and a navigation bar at the bottom that is common to all screens (slight tweaks for some screens, like different icons) in the middle is what I would call a view pane that needs to be updated with a applicable layout.
The status, nav bar, and each screen are defined in their own layout xml file. For my first swag at it I just used a ViewFlipper and loaded the 3 screen layouts into it. However that means that currently I have one main Activity which will not be maintainable as I continue to add screens.
It feels right to me that each screen layout should have an associated Activity class that understands how to control that screen. I need to figure out how to load that into the center pane dynamically. However I thought I read in another post that using multiple Activities can be a CPU and RAM drain.
Currently I tried making one of the screens it's own Activity and kick that off from the main Activity by creating an Intent and than calling startActivity. However that causes the new screen Activity to reside on top of the main Activity. The interesting thing is that then pressing the back button dismissed that activity and returns me to the main.
So far I haven't figured out how to setup having a different Activity control what happens in the center pane.
If I continue down the multiple Activity path, should my main Activity be inheriting from ActivityGroup?
Are using View classes more applicable in this case?
I know this has been a long post. I'd appreciate any advice.
Thanks!
CB

As you noticed, Android will implicitly track a stack of started activities in a task, and the 'back' button ends the top one, reactivating the next one down. I would advise you to think about which kinds of things the user might expect the back button to do, and make it so that activities are separated along those lines.
I haven't played with ActivityGroup so I can't advise you there. If you go with completely separate activities, you can have them all use the same "shell" content view with the common nav/status bar. Have a superclass or utility class handle populating and managing that from there. Then use a a LayoutInflater (you can call getLayoutInflater()) to fill in the middle with your Activity-specific view.
If you want one of the activities to have multiple screens, you might still end up with a ViewFlipper in the center slot. Again, you want to have an Activity transition wherever you want the user to be able to go "back"; that also means you may NOT want to have a change of activities in cases where screens are closely related or part of the same logical thing-being-done. (You can override the back button's behavior, but unless you have a good reason to, it's best to just arrange the app so that Android's basic setup helps your app's UI rather than working at cross purposes.)

If you want to use activities in the fashion you talked about, you might look into using a tab activity. It actually works in the way you want, you just need to hide the tab widget and put your navigation bar there instead. Or, you could go a little deeper and make you own similar tab-like ActivityGroup like Walter mentioned if you have more time.

You could use a view pager with fragments to accomplish the flip between the different views but still allow your activity to have full control over it. The activity can control the menus while the fragment controls your viewing area. This way your back button will properly dismiss the activity containing all pages related to the activity instead of walking down the stack.

Android Development: Switching between Views without losing onClickListeners

On my application I'm developing, the main.xml layout (the default layout of my app) has a few buttons that have been assigned onClickListeners (not the implementation way).
One of those buttons I want to have the ability to take you to another view. On the other view (preview.xml), there's another button that takes you back to the main.xml view.
I've used setContentView in the onClickListeners of those buttons and this works fine so far, but after you click the button that takes you back to main.xml, the buttons on main.xml have lost their onClick functionalities.
How can I get this to work right? I presume using setContentView isn't the right way to do this.

Your best bet, at Konstantin says above is to use Activities, as you will come across these a lot whilst developing for android. you can read about them here Activities. I assume you want to pass something onto the preview.xml page? If so, I'd recommend either putting it as an extra in the Intent used to start the activity (see the link) or creating a static reference in the activity (which you set before you launch it).

I'd say use two different activities and switch between them. Another option can be ViewSwitcher.