I'm helping a friend create an android app that will have screens with lists of info similar to a feed. I've been learning xml layout in Android and have some of the basics down, but don't have a lot of familiarity with doing the java stuff. I've successfully created includes to seperate layout files for compontents within a screen, but what I'm wondering is if such a component can be used as a kind of template for feed/list items that get inserted programmatically on the back end. IE, is there a way to have Android create a list and for each list item it uses the external xml as a template? Sorry if this is somewhat vague, I'm new to this and trying to understand what our options are. TIA!
Yes, every list item can be a custom layout. In fact you always have to define a layout for the list entries. You can either choose a prebuilt one from android.R.layout or you can use your own from R.layout. You can specify it when you create the list adapter in code.
Have a look at one of the ArrayAdapter constructors for example:
public ArrayAdapter (Context context, int resource, int
textViewResourceId)
Since: API Level 1 Constructor Parameters
context - the current context.
resource - The resource ID for a layout file containing a
layout to use when instantiating views.
textViewResourceId - The id of the TextView within the layout resource to be populated
The constructor takes a layout that will be used for the ListView childs. Works similar with other adapters.
What you usually do is inflating the layout inside getView() of the adapter though. When you did that, fill all the data you need into the views of the layout, and return the view.
Note that you get an argument called convertView. This is one of the older layouts you already inflated before. In most cases the user just scrolled down and that entry is not visible anymore. If this convertView is not null, you can fill your data in there instead of inflating the whole layout again (thats expensive).
You can find a working example inside the
ANDROID_SDK\samples\android-10\ApiDemos\src\com\example\android\apis\view\List5.java file. Also take a look at the other list examples in that folder.
Related
I want to create some CardView items dynamically, depending on items I get via a REST call. I created a CardView XML layout that contains many single elements with many settings. I don't want to write this XML layout in code to create it dynamically. Is there an easy way to do this work?
Each CardView item has its own name etc. therefore, the IDs of the elements inside the CardView must be different.
I think it would be a good idea that you take a look at this tutorial. https://guides.codepath.com/android/using-the-recyclerview
Basically what you want to do is create a basic CardView item, with its correspondent ViewHolder and inflate the contents of each item when you get the result from the API call.
I want to develop an Android app, where start page of the app GUI, will contain 4 vertical layouts in the main layout. Now, in each layout, I want to add buttons/slider dynamically from the app (instead of adding buttons/slider dynamically in the source code). That means, initially all these 4 layouts will be blank and when user will select any button or slider in another layout, to add it in any of this 4 layouts, the button or slider will be added in that layout. User will be able to add max 10 views in any vertical layout and the views can be either button, slider or custom view.
My attempt:
First I tried to create 4 vertical layout under the main layout for startup page and I got succeed.
I also find after searching that its possible to add views dynamically in layouts in android.
dynamically adding a view to activity layout
But most examples, add views dynamically in android by running loops, instantiating the desired view class and then add it in the main layout. Although, in this way, views are added dynamically in the layout, it is done by modifying the source code.
Is it possible to write the source code in a way, so that it can be done directly from the app? So that when user will click on Add a slider in "layout 1", a slider will be added in layout 1 and then again, when the user will click on "Add a button" in layout 1, a button will be added at the end of the slider. User will be able to customize button or slider properties. Also, if the user change the value of the slider, the app will remember its value.
Now, next time, when the app will be opened, those views will be there in the layouts, they will not be deleted and the values will remain unchanged (for example, a ticked check box will remain ticked), so I think I also need some kind of storage or properties manager.
My question is, is it possible to do this in android (because I never seen such apps in android) and if possible, any idea, how can I implement it?
I am totally new to android, so my knowledge is limited but I completed the basic tutorials on android app development and I have plugin development experience in eclipse.
Thanks a lot in. I will highly appreciate your help.
Of course it is possible:
Every layout (like LinearLayout, RelativeLayout etc.) extends the ViewGroup-class, which offers the addView-method.
To add a new view (like a Slider) to one of your layouts, just instantiate it programmatically (via new) in your activity and assign the appropriate LayoutParams to it
To store the state of user added content, it is the easiest to use SharedPreferences - a simple key-value-store which holds data over the application's lifecycle
Yes. This is possible. To create the Views dynamically, you simply have to either extend the class of the View or just say new Button(Context, AttributeSet); (Not only for Button's every View has a constructor that takes an attribute set and a context).
Using Layout.addView() you can add any View to the Layout.
Using SharedPreferences you can indicate what View belongs in what Layout.
If you decide to extend the View's class, make sure not to do too much in it. I tried that once and it just gave me an OOM (OutOfMemory Error) because I had a ton a Views trying to do stuff at the same time.
I am bit more concern of OOM on having a heavy UI on each item of a listview, example I have 100 items.
Below is the image that I wanted to practice and copy the UI layout. What would be the possible layout or how can I implement this type of UI. Each items are scrollable until the bottom, with separate contents but same layout. Please see my update below.
Update: I am planning to use card ListVIew, please guide me.
You can use simple listView or card ListView but make sure listView raw does not have many nested layout for avoiding nested hierarchy you should use Relative Layout in list raw
I think using a listview with custom row layout will be better for your app.This will help you to reuse the same layouts which are inflated when loading listview.Also please check the size of images you used in the rows.
Okay, So I just started Android development (I am average at VB.Net, so I understand basic code even if its not in VB). I've made a couple play around apps which used Text-To-Speech, Async Tasks and Reading/Writing files. However, I now wish to make a tabbed Android app.
I started the project in Eclipse Juno and filled in all the details. I then selected (For navigation) the Tabs/Swipe layout. I now have the default code for that layout type (Link to Tabs on developer.android.com - http://developer.android.com/design/building-blocks/tabs.html).
I understand mostly what the default code is doing. The only problem I am having, is determining the individual layout of my Tabs. I wish to have 2 Tabs, 1 in which the user selects an option, and the other, in which an image is shown depending on the selection in Tab 1.
So the question is: How do I create a .xml file in Layout to determine what is shown on the Fragment?
If you want to do this in XML the answer is simple, it can't be done just with XML, you must create a class that's implementing a ActionBar.TabListener.
Than you can override the onTabSelected method in which you can exchange the content.
A proper solution would be:
Use a LinearLayout as root container, and implement two Fragments for each of your Tabs (there you can design an individual XML-layout). Now you can add one fragment initially to the root-container and implement the exchange of the layouts inside the onTabSelected method and you are done.
This may be a dumb question, so my apologies if so; I'm fairly new to Android.
But anyway - I have a working ViewStub, which is replaced by different layouts depending different situations. It's working fine with regards to showing the correct layout when I call the setLayoutResource() method, and then setVisibility to VISIBLE. However, I now need some of the content in this view that is being shows to be dynamic (i.e. I need to set it via code rather than just show a static layout).
Is this even possible? The setLayoutResource() method only takes a static layout-resource ID, but I need that layout XML file to be able to have it's TextViews contain non-static text that comes from some code that I have ready to utilize. How should this be approached if possible? I understand the concept of having a Java class, and inflating the XML to attach itself to it to update the fields, but I can't see how that relates to my code at hand, since it's simply a layout resource int I need to set for the setLayoutResource() method in ViewStub.
I can post existing code if needed, but I'm not sure it do much more than clutter up the post. For reference - All I have is a simple layout XML file with some TextViews, and then my main XML containing the ViewStub, which is part of a custom Dialog. The user is able to instantiate the Dialog and set the layout, which in turn sets the layout of the ViewStub. This is the layout in which I need the dynamic content to be used.
Any advice would be greatly appreciated. Thanks!
Turns out this wasn't too difficult to accomplish. I just needed to use the ID of the TextView layouts after inflating the ViewStub to get a copy of the actual TextViews, then I was easily able to set their text to whatever kind of dynamic/custom text I desired.
I also needed to comment out the code that shows it via the .VISIBLE call, and instead do the following (the .inflate() line of code accomplishes the same thing as setting it to VISIBLE):
View inflatedView = dialog.myStubView.inflate();
TextView myTextView = (TextView) inflatedView.findViewById(R.id.my_text_view);
myTextView.setText("Dynamic/Custom Text");