This might be a silly question, but I would like to generate a layout xml file for android on the server, and when the user presses a button, the xml file is loaded into the android app.
Is this possible at all?
Instead of that, you can create any view you want, programmatically, without writing them in an xml file.
I do not think it is possible. The layout inflator documentation is here:
From the documentation the constructor:
public View inflate (XmlPullParser parser, ViewGroup root)
states:
Important For performance reasons, view inflation relies heavily on
pre-processing of XML files that is done at build time. Therefore, it
is not currently possible to use LayoutInflater with an XmlPullParser
over a plain XML file at runtime.
Why not just create the xml for the views and build them into the application? That is how Android Apps are typically done. If you want to support totally dynamically generated screens then it is going to be a lot of work. You could do it by developing your own layout sytax, and creating a view that knows how to dynamically render a view from that syntax. Essentially you would need to reinvent the layout inflator thats built into the OS.
Related
I'm developing a generic Android application that needs to get XML files from the server and set its contentview accordingly.
The XML files can be as simple as a relative layout with a textview or much more complex, that's really not relevant. The goal is to simply fetch XML files externally and display them or receive a string from the server, create a XML file locally on runtime and use it, both will do.
I've been looking for a while now and I didn't find any solution. Is there a way to do this?
According to this post which references Android's LayoutInflater doc; it is not possible since there's some "pre-processing of XML files that is done at build time."
In short, you can't use a regular xml pulled externally to inflate.
I am working on a project which will have lots and lots of Layout and Code changes.
My Question is pretty simple but I don't know anything about it. Would it be possible to dynamically load content such as Source Code (Java) and XML Layout Files on a Backgroundthread and then startup another Activity with the downloaded Content (Of either/and Java File + XML Layout)?
So that you change your Code and Layout online and download it on every start of the App?
Thanks alot in advance.
You can load classes dynamically. But as for xml layouts that is hardly possible sobeit you are going to write your own parser and inflater. Unfortunately LayoutInflater can't inflate external files. This is from LayoutInflater documentation:
For performance reasons, view inflation relies heavily on pre-processing of XML files that is done at build time. Therefore, it is not currently possible to use LayoutInflater with an XmlPullParser over a plain XML file at runtime; it only works with an XmlPullParser returned from a compiled resource (R.something file.)
So you are basically restricted to create all your UI from the code only.
I thinks it's probably not possible for security reason but just want to be sure: is it possible to create layout in Android from an external XML file?
To be exactly: I'm creating XML output with XSL on a remote server. I could create the necessary layout direct on the server and then download it to my Android App.
It is impossible. XML layouts in Android are NOT stored as XML. For performance reasons, they are pre-processed during compilation and stored in binary form, and layout inflater only understands that binary form rather than xml.
Of course you can create Views dynamic at runtime, while I'm not shure, that this is the best solution. If you have a look at the internals of Android, every View which is created through XML is called with a Constructor with two parameters: Context and - even more interesting for you - an AttributeSet. I think you have a lot of work with parsing it, while keeping track of the right format.
You could at least set the values and build your views yourself in Java depending on Server output.
YES, right now is possible with ItsNat Droid, take a look:
https://groups.google.com/forum/#!topic/itsnat/13nl0P12J_s
It is still under heavy development but most important features are already implemented.
it's possible, but I found way to load only simple layout:
Resources resources=context.getPackageManager().getResourcesForApplication(targetPackage);
int resID = resources.getIdentifier("widget_layout" , "layout", TARGET_PACKAGE);
XmlResourceParser parser = resources.getLayout(resID);
View themeLayout = LayoutInflater.from(this).inflate(parser, null);
Maybe the inflate function of the LayoutInflator works for you.
EDIT: doesn't work yet it seems.
In my andriod app, I get a xml at run time.
How do I inflate the view from the uncompiled xml ?
The xml is choosen by the user from his file system.
Its not compiled.
Hence I do not have any reference like "R.layout.my_layout"
Try LayoutInflator.inflate():
LayoutInflator.from(this).inflate(R.layout.my_layout, parent, true);
where this refers to the containing Activity and parent is the ViewGroup you are inflating into. You can also use this with a null parent (and false) if you just want to get back a view hierarchy and add it to a ViewGroup yourself.
This can't currently be done using standard android APIs. The XML files containing the layout needs to be processed during build time to be able to inflate them at run-time
See the documentation of the LayoutInflater here http://developer.android.com/reference/android/view/LayoutInflater.html
For performance reasons, view inflation relies heavily on pre-processing of XML
files that is done at build time. Therefore, it is not currently possible to use
LayoutInflater with an XmlPullParser over a plain XML file at runtime; it only
works with an XmlPullParser returned from a compiled resource (R.something file.)
One somewhat tedious option is to write your own XML parser to parse the XML and construct the layout programatically.
I want to write an app where (at least for now) the content is always the same but the layout is loaded dynamically at run time based on a user preference. Essentially I want the app to apply a "skin" which may look completely different to other skins.
I found some tutorials using SAXparser:
http://www.androidpeople.com/android-xml-parsing-tutorial-using-saxparser/
http://twigstechtips.blogspot.com/2010/12/android-how-to-parse-xml-string.html
and can imagine writing something from scratch that recognizes all the standard xml layout tags and then dynamically loads each part of the layout. But that's a lot of work to do from scratch! Surely this functionality is available in android, or surely someone has written some open source code which can be run at the start of your activity's onCreate method, which takes in an xml file and sets your layout?
I found a similar but unsatisfactorily answered question here:
How to create a layout file programmatically
which makes me think that since setContentView must take an integer resourceID as its argument, the fact that these are pre-baked at compile time might be a problem. (setContentView may also take a View object as its argument, but I don't want a ton of if statements and to pass it each View object one by one, I want some code that inputs an xml file or xml string and sets the content view.)
Maybe I'm way off track. Is there another way to do this? I would think that the ability to have an app with dynamically loaded skins is important.
Thanks!
I had similar requirements and tried the same approach - it does not work.
Documentation clearly states this: http://developer.android.com/reference/android/view/LayoutInflater.html
Update:
Since OP needs to load XML layouts created at runtime:
Possibly this could be done, by creating XML layout files, copying them to dummy project, create .apk and then load apk on to device.
DexClassLoader can be then used to load classes inside apk.
well, android makes the hard work for you, but no all the the work....
first that all you have to forget about parsing xml layouts... instead you can make skeletons layout, that manages his inner childs position, size, etc... and later inflate that 'skeleton' xml with LayoutInflater and obtain a View instance...
When you have that View instance then you can do what you want with it, applying the users preferences like backgrouds, foregrounds colors, position, sizes, etc...
maybe i dont understand your question but you can get any view inflated from a xml resource at compile-time and later apply other style or set another propertys
It seems it is impossible to load the layout & change the skin dynamically according to the doc :
Therefore, it is not currently possible to use LayoutInflater with an XmlPullParser over a plain XML file at runtime; it only works with an XmlPullParser returned from a compiled resource (R.something file.)
http://developer.android.com/reference/android/view/LayoutInflater.html