Im in the conceptualizing/design phase of building an app and i've hit a bit of a snag. Essentially i was looking for a way to embed one activity into the UI of another similar to how a TabHost/TabActivity. There would be a window at the top of the screen which would contain the other activity, and below that would be buttons and controls that are independent of the above activity and should always be visible. The user would be able to navigate from one activity to another in the window without causing any change to the below controls.
While looking into the issue i ran across ActivityGroup, which looked like it would be useful, but how would i implement it? Anyone have experience with ActivityGroup or have another idea?
Yes, you'd implement an ActivityGroup, which will be the container of your other Activities. When the user clicks one of the buttons, you'd get a reference to the LocalActivityManager, and use it to start, and embed the inner activity. Something like this:
LocalActivityManager mgr = getLocalActivityManager();
Intent i = new Intent(this, SomeActivity.class);
Window w = mgr.startActivity("unique_per_activity_string", i);
View wd = w != null ? w.getDecorView() : null;
if(wd != null) {
mSomeContainer.addView(wd);
}
Note, using this method can be pretty complicated, because unless the focus is just right, pressing the hardware buttons (like the menu button) will only only trigger events on the ActivityGroup instead of the inner Activity. You have to find some way to focus the inner activity after you add it to the container view, at which point the even will happen in the inner activity and propagate to the container activity.
It can be done, I've done it... and it works. It's just a bit more complicated than I think it should be.
Anyway, I got most of this information by looking at the TabHost code, which can be found here
Related
I have implemented a TabHost. In one tab I have Activity1, which calls Activity2 after a button click, which calls Activity3 after a button click, which calls Activity1 after a button click, etc.. No backstack functionality is required, just 1 --> 2 --> 3 --> 1, etc. All three activities have a separate layout file.
Everything works fine, except that after the first transition from 1 --> 2 the activities grab the entire screen and the tabs are invisble forever.
Question: how can I keep these three activities within the confinement of de tab area and the tabs visible? The problem has been recognized here many times before; the solution used to be ActivityGroups, but these are deprecated and Fragments are advised instead. I have seen many examples here, but nothing that could help me.
Can I keep my three activites (Activity1 extends Activity, etc)?
Should I add fragment tags to the layout files?
Do I need to work with transactions?
Should I work with one fragment class or three?
Can you please give me a few hints how I should go about? I woud already be helped if you tell which classes I need to use and of what type they are.
Thanks in advance.
It took me more than half a day, but finally found a solution that works. Unfortunately I am still stuck with deprecated issues (Activity Group and getLocalActivityManager().startActivity(..)).
Again I have a single tab under a TabHost and several activities, all operating within that tab. Navigation from one activity to the next occurs with a buttonclick. Solution:
all Activities operating within the tab need to extend ActivityGroup
All Activity classes need to have a button handler that links to the next activity like this:
public void onBtnClicked(View view) {
Intent intent = new Intent(view.getContext(), NextActivity.class);
replaceContentView("NextActivity", intent);
}
public void replaceContentView(String id, Intent newIntent) {
View view = getLocalActivityManager().startActivity(id, newIntent.
addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)).getDecorView();
this.setContentView(view);
}
By this the tabs remain visible all the time, as desired.
Hope this helps someone.
I'd like to recreate a functionality similar to a Swing GlassPane to be able to display animations while the user uses the app "below" normally. I cannot simply create a separate layout and attach it to each activity since the animation state would be lost when switching activities.
Is there a way to keep a persistent view over all the activities of an Android application ?
Thanks.
No its not. Every Activity runs in its own thread and is by design supposed to be runnable standalone.
But you could persist the animation state into the DB or into sharedPreferences and start it over at the new activity.
What you could also do is to use a Spinner or another control instead of seperate activitys. Then you could have a persistent view.
why not think in a TabActivity?
hi! i do this before with a TabActivity, never with an only activity, always with many activitys wich i started, get theirs windows and setting as my TabActivity window´s decor view... i dont tested the code below, since is an idea, but maybe more lately (when i'll be on home) i'll write an example...
So, my idea...
a TabActivity is composed by a TabWidget and a FrameLayout where the activity´s windows is allocated.
the TabWidget can be any view, so, you can put the animated view here.
the most difficult thing is the fact that, if you start an activity from the TabActivity´s child, then the new activity will be on top of the TabActivity. In order to overrides this behavior the TabActivity must know when a nested activity wants to start another activity. When this happens the TabActivity must clear his decor view (with the old window activity) and put the decor view of new one. Something like this:
on the child activity, launch a new activity when we click on a button:
... on click listener...
((MyTabActivity)getParent()).createNewActivity("NewActivity", NewActivity.class);
now, we´re saying the TabActivity that it has to start a new activity, get the new activity decor view and put that view inside the TabActivity decor view... so, the createNewActivity will perform something like this:
public void createNewActivity(String activityId, Class<?> class1) {
Intent intent = new Intent( getIntent().getAction() ).setClass(MyTabActivity.this, class1);
Window wList = getLocalActivityManager().startActivity(activityId, intent);
getWindow().setContentView(wList.getDecorView());
}
hope you understand me.
i'll write an example later
I have a tabhost with three tabs. Each is an activity. I would like to have a button which is in the action bar, the bar along the top with common buttons, call functions of the tab which is active.
For example, an add function which could add something different to each tab depending on what tab was present when you clicked the button.
So, I am aksing how to call a function in Activity A from the tabHost.
And if that wont work, perhaps I can update the database from the tabhost and then refresh the tab content. Would that be easier?
Thank you all for you time and support.
I used the following code within my TabActivity class to switch tab then call a public method defined in the activity of the tab:
getTabHost().setCurrentTab(0);
Activity MyActivity = this.getCurrentActivity();
MyActivity.myMethod();
Hopefully helpful to someone looking for the answer to this question.
Hi Just stumbled across this, not sure if you already found a solution?
I solved this myself recently. I was previously getting around the problem by raising a intent broadcast from the tabhost activity and receiving the broadcast within the sub tab activity. This worked for me but i was sure there is a "better" way.
A cleaner way is to achieve it with something like this:
might have something like this:
parentActivity - my "container"
activity which holds the TabHost
childActivity - my tab activity
which holds tab content and the
public method i want to call from
parentActivity
within parentActivity:
// a method used for onclick callback or whatever you need. within parentActivity (tabhost)
// this will get call huzzah() in the first tab - getChildAt(0)
onClick () {
childActivity childAct = (childActivity) getTabHost().getChildAt(0).getContext();
childAct.huzzah();
}
within childActivity:
// a public method for the parent activity to access
public void huzzah() {
Log.d("stuff", "huzzah() called");
}
Note: Another alternative i believe is to redesign to use views instead of activities in your tabs. This is a better overall alternative because IIRC memory wise you are only storing 1 activity on the stack rather than (n * tabs) number of activities
Hope that helps
Edited as per Peter O request:
I am on API 10, and this problem gave me a huge headache. I have 3 tabs, I want all of them to be aware of changes on the other. The problem I had was that once the activity for a tab is started, there seemed to be no call back so the activity understood the user switched to a different tab, and thus needed to do work to be sure its state was correct.
I found lots of answers to this problem, but none seemed to work.
The one that I finally got to work was the solution offered as #3 for this thread --but it too is confusing. I found that the getTabHost().setCurrentTab(0); does nothing; I implemented OnTabChangeListener() to call a function that used getTabHost().setCurrentTab(0); however, I found the getTabHost().setCurrentTab(0); caused the app to crash for any tab other than 0--e.g, If I chose tab B (index=1) then called getTabHost().setCurrentTab(1); the app crashed.
Using the Debugger, I found the call this.getCurrentActivity(); always returns the activity associated with the tab which the user clicked on--calling getTabHost().setCurrentTab(); did not change that fact, and caused the app to crash.
So I got rid of it and I can now call this.getCurrentActivity(), then call a method in the Actvitity class returned by that call --this lets the activity know it has to update it's state--in my case it does this using the application object.
The above way of calling the method will not work,
Here is the quick answer for the above problem:
getTabHost().setCurrentTab(0);
Activity myActivity=getCurrentActivity();
String name=((Tab1) myActivity).et1.getText().toString();
Here the above code is given in the onclick() method of the activity which has TahHost
where Tab1 is the secondactivity and et1 is the identity of the edittext in the Tab1 activity so you can get all the value of the different fields like this individually.
I would need to know how to handle the intent between tabs. For example, I have a tab activity with two tabs. First on content is a text view. another one is a map view. When i click that text view it redirects to the tab2. it can be easily achieved by setCurrentTab(1) or setCurrentTabByTag("tab2") methods. But i want to pass lat and long values to that Map Activity to drop pin. What is the better way to use intents or getter/setter in java? What do you prefer? if your answer is "Intents". How?
A interesting problem. I understand it that you want to change to the second tab on a click in the first tabview but also pass special data to the second tab that is dependent on the action in the first tab.
I would generally start your views inside the tabs with an activity. However this is done at the moment the tab host is configured. That means both intents the one for the activity that lets the user choose lat long and the one that shows lat long are openend at the same time.
Therefore you can't add the information to the intent used to intialize the tab host.
I don't like the solution but the only thing that comes to my mind (using different activities for the tabs) is using a custom application that stores a reference to an object containing the data that you need to update the view in the second tab. You have to extend application with an own class and add this class in you manifest, now you can call getApplication in the first tab cast it to your application class set lat and long just before you call setCurrentTab. In the second tab you can call getApplication() again and you will then get the application object that is the same for every activity at every moment of your app running. You then have cast it again to your application object and retrieve lat and long value. See this page in the google refs on how to use a custom application class.
To use a custom application class add the following to your application tag in your manifest:
<application
...
android:name=".somepackage.CustomAppClass"
This will tell Android to instantiate the CustomAppClass as your Application class at the moment your app starts. You need to extend Application to avoid errors on start up.
Another solution but not the one I would prefer is to initialize the views yourself and initialize the tabhost with views and not activities. With a map view in one of the tabs this could be very memory heavy.
If you want to pass values between activities, I suggest looking at
http://developer.android.com/reference/android/content/SharedPreferences.html
the best way to get values from one itent to another.
With sharedPrefrences, there is only one instance of the class for the whole application, which means that you can store values in the files, switch intents or activities, and then recall those sharedPrefrence files that have the data in them.
The only downside is that you have to pass primitive types (int, string, boolean) but I'm sure you'll figure ways around this :).
I dont see the Problem here:
Maybe its a little bit of hackish but following Code works for me:
public boolean onClick(View v) {
//get your data you wanna send.
//If it is an Object it would be good if it is Parcelable
Object o = getYourData();
// or Parcelable p = getYourData
Activity activity = getParent();
//I'm assuming were inside an Activity which is started by TabActivity
if (activity instanceof TabActivity){
TabActivity ta = (TabActivity)activity;
//now determine the Tab you wanna start
ta.getTabHost().setCurrentTabByTag("yourTag");
//or ta.getTabHost().setCurrentTab(yourID);
Activity current = ta.getCurrentActivity();
//check if the Activity is the one you wanna start
if (current instanceof YOUR_ACTIVITY_YOU_WANNA_START){
//Cast to your Activity
YOUR_ACTIVITY_YOU_WANNA_START yourActivity =
(YOUR_ACTIVITY_YOU_WANNA_START)current;
// you only need to put Data inside your Intent
Intent intent = new Intent();
intent.putExtra("EXTRA_DATA_TAG", o);
//your Activity must Override onNewIntent and make it public,
//or simply add another method
//with whatever You like as parameter
yourActivity.onNewIntent(intent);
return true;
}
}
return false;
}
this way you don't have to mess with Application, SharedPrefs or other unnessesary stuff mentioned here
If you make the intent you are using to start the second tab activity a global intent.
You can then add extra's to this intent in the onPause() of the first tab. Note: you have to define all your tabs in separate activitys than your tabhost TabActivity as this activity's onPause() is never called.
This also help's with the answer above, if you are using a global variable saved in your activity that extends application, you can set this in the onPause() as it is fired before the activity is switched, which you might find an issue if setting this elsewhere
There are 4 Tabs in a TabHost, let them be A, B, C, and D. Now each one is just an index page and clicking on any of them shows a different activity.
The problem is that I need to start another activity when the user selects something from the content displayed in the tab. The other activity should also be displayed in the parent tab itself. Is it possible? Or will I have to try something else?
Try this, found this solution in android cookbook,
http://androidcookbook.com/Recipe.seam;jsessionid=5424397F3130CE7769FF47DD67742911?recipeId=1693&recipeFrom=ViewTOC
Can't you change the contentView of your tab instead of starting a new Activity ?
Maybe I'm wrong but I think also that starting an activity in a tab isn't possible because the TabView is hosted in a activity and not the opposite (Tabview don't host an activity per Tab).
I think the common consensus is that it is best not to use individual Activities as tab content due to these limitations. See these questions and answers for pointers to alternatives:
Android: Why shouldn't I use activities inside tabs?
Android - Tabs, MapView, activities within tabs
To summarize the link that Rukmal Dias provided. Here's what you do:
Change your current Activity (that's in a tab) to derive from ActivityGroup
Create a new intent for the Activity you want to switch to
Copy/Paste and call this function in your current activity where "id" is the "android:id" for the layout of the new activity you want to switch to
public void replaceContentView(String id, Intent newIntent){
View view = getLocalActivityManager().startActivity(id,newIntent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)) .getDecorView();
this.setContentView(view);}
Here's an example of how I make the call to switch views from my current Tabbed Activity:
public void switchToNextActivity(View view)
{
Intent myIntent = new Intent(getApplicationContext(), MyNextActivity.class);
replaceContentView("next_activity", myIntent);
}
It looses the view hierarchy. When you press the back button, in my case, the app closes.