I have 2 different activities that share one layout.xml file. If I decide to make alterations such as TextView.setText() in one activity, would the other activity experience the same change? Or do the activities just create different instances of the same layout?
If you alter the view in one activity, the other won't be affected since you can only have one activity shown at a time so the other one will have to be recreated and redrawn on the screen.
Related
I am trying to find a way to show two activities on the same screen, I have two activities main and content activity, the main activity has a mini-player that's implemented and only works in an activity and the content activity has some implementations that also only work in an activity so the solution of converting them into a fragment does not work for me. I need to find a way to show the mini-player in the main activity inside of the content activity. I have looked online and none of the solutions so far have been working for me!
You have 2 ways to complete task.
Fragments, They can do same things as activity. Its lite weight activity class with more flexible to attach and detach from the screen.
Views, If you think your task can be done by only activity then use views for it. you can apply different animations and show/hide feature to display content on the screen within single activity.
Fragment is a part of an activity, which contributes its own UI to that activity. Fragment can be thought like a sub activity. Where as the complete screen with which user interacts is called as activity. An activity can contain multiple fragments.Fragments are mostly a sub part of an activity.
From document
For example, a news application can use one fragment to show a list of
articles on the left and another fragment to display an article on the
right—both fragments appear in one activity, side by side, and each
fragment has its own set of lifecycle callback methods and handle
their own user input events. Thus, instead of using one activity to
select an article and another activity to read the article, the user
can select an article and read it all within the same activity
Use Fragment.Fragment are Runs inside the Activity.
you can display multiple fragment in same time.
Refer Fragments
Create a fragment
At first, Android system can show only one activity on the screen.
You should not use Activity.
Please use Fragment. You can use multiple fragment on the same screen.
im developing an application with multiple screens using activities and fragments. The principle behind my decisions to use one or the other are based on the interaction in the application.
I have come to the conclusion that you should use an activity whenever major UI elements remain present after an event has occurred that forces the views inside the UI to change (An example of this can be a tabhost nested in the toolbar styled as the Google Play store android App with multiple fragments as childs. Another example is fragments representing the different rows or clickable elements on a navigation drawer).
So right now im presented with the dilemma of choosing once again between the two (fragment or activity) for a UI element that is going to be present across my whole application. Its triggered by a floating action button that launches a creation tool for an element inside my application and i needed to be accesible across all of my apps screens.
So to sum things up, what i need to know if its better to use a fragment or an activity for an element that is ever present across my whole application.
Thanks in advance
Use Fragments or a compound Views. But both in the right way.
Fragments are thought for reusable combinations of views. Compound Views are Layouts containing views. They are the right way if you want to create views from more primitive views, for example a View containing TextView and a increment- and decrement-button.
Fragments are more Activity-like. They have a real lifecycle. Your description looks like you want to create acitivity-parts. And thats exactly what fragments do.
A Fragment represents a behavior or a portion of user interface in an
Activity. You can combine multiple fragments in a single activity to
build a multi-pane UI and reuse a fragment in multiple activities.
Taken from Android SDK Documentation: Fragments.
I've read Activity and Fragment sections of Android API and many Q&A on these two, but I still don't have a clear understanding of some points.
When android SDK creates an activity for me, it also creates a fragment for it. From what I know I can bind several fragments to one activity and switch them as I like. But I don't understand if I ever have to add any components to activity xml file? I mean all layouting and buttons are in fragment xml. In what situations and why would I need to use activity's xml file? Can I make buttons, for instance, both in activity xml and fragments xmls? Is it a good practice?
What logic should be generally implemented in activity class and what in its fragment? For example, I think that Fragment class is needed only to get data from UI and pass it to activity. Is that right?
Thank you for your patience
An activity is basically a screen in your application (think of it as like a webpage) with all associated logic. A fragment is a sub-activity, a portion of an activity with its own set of logic and UI.
You should use a fragment when either you use the same UI in multiple activities, when you want large parts of your activity's UI to change in and out as people take actions, or when you want to rearrange large parts of your UI in different layouts. When none of those are true you should ignore fragments and just use activities directly. In my experience it ends up being about 80% activities and 20% fragments, but it really depends on what type of apps you're developing- tablet apps use a lot more fragments, for example, because they have more screen real estate.
In my application i want user to fill in a large form (5-10 fields). Not all the fields are EditTexts, some are Spinners, RadioButtons etc.,
So instead of have them all in a single layout(user may leave the screen, seeing so many questions). I thought of having it as a Conversational/ questioner like thing.
On submitting each answer eventually shows a new question.
Instead of having separate Activity for each question, better i change the ContentView of the same Activity.
Solutions like:
1. Make View's Visibility Visible/Gone depending on the question to be asked
2. Change the ContentView and all onCreate().
are inefficient when i have to change the ContentViews or Visibilities 10 times.
Should i use a Fragment in the Layout and replace it with new Fragment?
Even that way i end up having 10 Fragment classes and 10 layouts 1 each for th Fragment Classes.
Is there any other way to implement this. Right now i am doing it using Fragments.
Thank You
I believe, Fragments would be the best choice here, since either ways (i.e. either dynamicaly or creating layout files) you have to write it 10 times.
So better would be Fragments, since, each layout will get replaced with the previous layout dynamically.
But you also have to consider one situation here,that is, if in future, you have to add new questions in your form, then you will have to do a lot of modifications in the code, otherwise, this is the best place to use Fragments.
I had a similar situation where the user had to fill in a few requests, there was a status and navigation pane which remained constant throughout the app, so it didn't make sense to start a new activity every time. So I made a main layout with a three Linear layout utilising the top and bottom for navigation/status and the middle was used to display the questions.
I created the different layouts and inflated/deflated them as required since i had only a few (3) layouts. If the number of layouts increases then the method to keep track and inflate/deflate them might become complex.
Adding and removing layouts/questions is rather easy, if you have a sequential flow. One downside to this approach is the backstack, you have to implement the logic yourself as you stay within one activity and a backpress will exit the activity. This approach also has some advantages since all the data you collected in the questionare is readily available and is a boon if your next questions are based on the previous answers, it reduces a considerable amount of work in having to pass them along in intents.
However, I do not have much experience with Fragments since I opted for this approach since it was much simpler than fragments and required less time to implement for my requirements.
I've recently decided to update my app to support the new fragments feature in honeycomb 3.0.
My Application currently works on a list view that opens different activities depending on which list item is clicked.
Using an adaptation of the code in this tutorial I have created an app that consists of only two activities, but depending on which list item is clicked the second "viewer" activity launches using a different layout xml.
Unfortunately I haven't been able to figure out how to call the old methods that had all the functionality. Should I Import all of my old activities and then call the methods into the viewer activity (I may need some advice on how exactly to do this) or should I just put all the methods directly into the same viewer activity (please consider the size of these methods(which is very large by the way)).
Once everything is working with two activities upfront then it will be a pretty simple task of "fragmenting" the app as demonstrated here
Although I haven't considered that there might be a way to allow multiple fragments to occupy the same space in an activity(If this is the case then please let me know how it's done)
Thanks
As James has pointed out you will have to move the business logic from your Activities to your Fragments.
To handle events you can create a listener Interface. The CONTAINER activity/ies will implement this interface. As fragments has access to the container activity you will be able to delegate to the container Activity the "logic" for the desired events. For this events the activity will decide whether to launch a new activity, show/hide new fragments or whatever.
I had a similar question, take a look to the question and answer: here
Although I haven't considered that there might be a way to allow multiple fragments to occupy the same space in an activity(If this is the case then please let me know how it's done)
I think its possible to allow multiple fragments to occupy the same space in an activity. Again, take a look to the answer here ... I think the concept/scope of Activity has change a bit and now an Activity can contain different Fragments which every one will allow user to do a single focused thing.
I'm not sure what you mean by "call the old methods that had all the functionality". You'll want to rewrite all of your activity classes as fragments. Check out this tutorial here (it's very concise). Basically, you'll want an activity that consists of a ListFragment and a FrameLayout. Your ListFragment will update the FrameLayout by changing to the appropriate Fragment based on which row was selected.