I've seen that some Android devs promote this form of declarative layout:
<TextView style="#style/my_textview_style" />
i.e. that pretty much all the attributes (including the ID) go into the style definition. It certainly makes for shorter layout files, but is it a step too far?
What would you recommend goes in the style definition, and what should stay in the layout, and why?
I've started doing Android dev this year, but have prior experience of development. Issues like this are so important, the "way" we use the tools, the habits, to be more efficient. I appreciate you sharing your views on what works for you, for clarity, for efficiency, for maintainability, for app reliability.
I've pondered this very question and it becomes much more pertinent when dealing with multiple device sizes and densities.
Putting too much information into the styles can limit their use, especially when dealing with landscape and portrait layouts. For example a landscape layout may in fact be wholly different in composition but require very similar styles.
In these cases it helps to use the . notation to ammend style differences, for example.
<MyPage>
<MyPage.portrait>
<MyPage.landscape>
See below for information on the above approach to creating styles.
http://developer.android.com/guide/topics/ui/themes.html
MyPage defines the common properties for your layout and you then override these values in the portrait and landscape extensions.
I..e you might have more right and left padding in landscape than portrait.
The problem i've found is that the themes and styles xml files get huge, especially if like me you have many activities, and if you address lots of creative changes then you can end up with lots of messed up definitions.
At this point you have to take stock, tidy up and re-factor.
My only advice is that you plan really well upfront. Define a naming system that accommodates your project, write it down and stick to it.
Possible style naming convention
<section>_<componentName>_<componentType>_<orientation>
home_leftPanel_btn_horizontal
home_leftPanel_listview
home_leftPanel_listview_horizontal
A similar approach to themes should be adopted.
I'm still working this out, so can't give fuller examples.
Pushing those things out into the style is a good practice if you plan on skinning your application differently. If you plan on releasing two versions with just a different look then by all means push those into a style. As you say it cleans up your layout files quite a bit.
Should you push IDs into styles. No because IDs are the hooks by which you're code will grab references to those objects. I can't see much of a point to always having your program externalize IDs. So I'd say that practice is going too far.
Now should you do this every time? Well I think that really depends on if you think you need the benefit this brings to reskin the application. Some people can't say no to a good idea, and try and do every good idea all the time. While that's admirable it's not productive. Experience is knowing what good ideas you need and what good ideas are just fluff for this application your are working on right now. To keep ourselves productive we need only the good ideas that make us move faster, and all other ideas are just art. How do I choose? Refactor, refactor, refactor. Do it fast, then refactor to clean it up based on the next requirements I'm working on. Do it fast, then refactor. Repeat until my boss smiles.
Related
I have been wrestling for at least one year with trying to understand how to master/get insight into Themes and Styles, but haven't come further than grasping parent relationships (and I think I read somewhere that such relations behave more like macro's rather than like true inheritance.)
To give a simple example: this nice looking SO answer frustrates me: what is the relationship between themes, styles, platforms, support library, API levels, etc... (and not speaking of the fact that custom styles don't need to use "parent", a dot notation suffices - why is this so different?)
The link talks about beasts such as ThemeOverlay, "?attr/colorPrimary", "app:popupTheme", device themes, native themes; where are all those beasts? How can I use them? What do they mean?
Android dev doc admits that this is all poorly documented, and suggest to dive into the source code. but I don't feel much to explore the link they give. I mean - I'm sure I will find out if I dive into the source code, but I have better things to do than debug AOSP... And if I look at eg this, all I get is a totally useless literal.
I'm aware this sounds daunting, but I can't get to reach my arms around this "big mama"... It feels like if one was not part of the AOSP movement from the beginning, it's very difficult to catch up.
After trying to make sense of the Metrics and Grids page of the (fairly new) Android Design website, I gave up on a lot of things. So, basically, I'm trying to find the original layouts that are used in Android 4, so that I can apply the same concepts.
To make this question more objective and not fail under the "too broad" axe of stackoverflow, I ask you for the layout that is used to recreate, exactly and fully, the examples on that page. Did Google provide them in the samples? Maybe a well known didactic repository that strives to conform with standards?
Just as an example, it's not clear what to do to recreate the "48/3 metrics" (16/16/16) in order to make the text fit in it. What if I want to use 1-line of small text? Would it be 16/wrap_content/16, or 16/16/16 to make it consistent with other layouts around the set? What if...
I believe this would not only help the small devs, but also and most importantly, help standardize the look and feel of apps in Android Play. The site is a good start, but far from ideal.
Added details
I never asked a question with this much upvotes, and I didn't even expect that (I have other questions that I regard as "better", but by far not as many votes and favs). Not that I care about votes, of course, but that is to show that there is a great demand for what I'm asking (a bit of an ad populum here, but still...).
Replies to comments
#Ricardo Amaral:
I'm indeed sorry if I wasn't clear enough:
Mandating a standard and requesting unambiguity from it are different issues. One of the reasons I like Android is the degree of freedom we have, so I'm very much aware of the impossibility of mandating most of the common practices.
I believe it relates to the concept of "reinvent the wheel" within the concept of freedom.
Again, those were just examples. Some things are not clear... which are paddings of the outer container, and margins of the inner views? Many times that makes a difference in selectors, dragging etc. etc. etc., and that again translates into a familiar look and feel for the user. One thing feels like splitting hairs, but it quickly adds up to a lot of small differences. And the user notices it... it looks like it lacks that last "finishing touch".
#Michael Slade:
I know they're examples, that they may have been wireframed from templates. As said, I'm already reusing code from the SDK, and I know they're just examples and that we can deviate from them. Again, after all this time, nobody answered.
Optionality benefits from precision. That's what I'm trying to say and ask. Because it's a recommendation doesn't mean its guidelines can be whatever you want them to be. If you do that, it's not the recommendation anymore. That's the whole point of recommendations, by the way: provide an implementarion theory without forcing anyone.
Thanks everyone!
Hate to break it to you but it's likely that the images on the page you like were created with a drawing program, and there are no example to go with them.
Without someone actually going to the effort to create samples for you, your best bet is to go through the samples that come with the android SDK - they will follow the guidelines in most cases.
And remember, they are just guidelines. At the end of the day it's up to you to create a pleasant and smooth user experience, however you see fit.
This question has been bugging me for some time. I've already developed a couple of apps on the Android platform and somehow always find myself resorting to Java code in order to construct the layouts. In a professional development environment, is this acceptable? Or should XML files be the go-to approach? I usually find XML a more tedious approach and often, these layouts don't look the same on all devices. I just don't get it. From a professional viewpoint, has anyone really been able to develop apps with complex views purely using XML files? This question is killing me because Google recommends using XML but the UI never looks the same on all devices unless done programmatically. Or am I doing something wrong?
Note that I'm referring to Android 2.2 and 2.3, which majority of the users use.
I use XML layouts on pretty much every fragment and activity of every app I write. I very rarely see any need to create Views dynamically, tho configuration of ListViews, showing/hiding views, etc needs doing in code. For me the advantages of XML are:
Ability to use layout editors (Eclipse)
Easier to preview layouts
Possible to benefit from auto-localisation of layouts
Easily maintain different parallel layouts for difference devices (screens)
Can get a sense of the layout by looking at it (easier than code)
Easy to break layouts down into pieces (fragments, includes, etc) to remove duplication
Keeps a separation between the visual design, and the functionality behind it
I can't think of any good reasons to put all my layouts into code - that sounds like hell.
I expect the reason your layouts don't look the same is because your XML is not defining the layouts correctly. Bear in mind the Android tools convert XML layouts into code, so there's no inherent problem with using XML layouts versus dynamic - both end up as code.
OckhamsRazor,
The answer very much depends on your needs, flexibility, and knowledge. The first thing to understand is that every Layout, whether created via XML or programmatically can be tweaked specifically or made to conform to many screens via properties.
... and somehow always find myself resorting to Java code in order to construct the layouts. In a professional development environment, is this acceptable?
Yes, it is. Android makes those available so you can do just that. However, the benefits of managing layouts via XML include standard MVC segregation, simpler debugging, and an easier time modifying the resource, if needed. Additionally, you may maintain multiple copies of Layouts depending on device configuration easily.
... has anyone really been able to develop apps with complex views purely using XML files?
Absolutely! There are some amazing programs that fully utilize XML rather than programmatic views. The key to them is how much information (that is non-standard view properties) is required from parental Views. Even in those cases there are ways to pass that information provided you know where and how to do so.
Or am I doing something wrong?
I don't think so. Honestly, I've run both ways depending on need. I'd say it really comes down to your lack of knowledge of the quirks. But the job is to get the job done. Here's an example: There are some times when I don't know how big everything needs to be until its run on the device, and there are times that I make the device conform to my layout's needs. Ultimately, I use the following chart to make my determinations.
Do I need information from parental Layouts that is aside from view properties
Do I need to dynamically size more than one element independently.
Is the View type pre-determined or will it change as well?
If the answer to 2 out of 3 of those is "yes", I will use some level of programmatic layout. If not, I will go pure XML. That being said, programming is one of those professions that encourages ingenuity (provided it is safe) and nearly anything can be accomplished in any number of ways. Ultimately, I'd say do whatever makes your job making quality apps easier.
Google makes its recommendations based on their own knowledge of software programmers and their general practices. They also created the platform, so they know which things are optimized in which ways. Its all about experience and we all have our own. If you have trouble utilizing XML, its worth taking the time to figure out the quirks simply so that it is another tool to utilize. Also, it will give you the information you need to answer this question for yourself.
To sum things up: I could say chocolate is better, but if you like vanilla, you'll disagree. Be aware of the drawbacks and benefits of each and take the time to learn how to accomplish the same tasks with both methods. It will make you a better programmer and give you a better sense of when to use which technique.
Hope this helps,
FuzzicalLogic
I typically do a lot of work with highly customizable UIs, where large portions of it need to be done in code. That being said, wherever possible I try to use layout fragments and inflate them, so as UI sections are added, removed, or rearranged I'm still just doing some of the layout, not all of it.
That being said, it's not that hard doing layout via code. The big advantage to it is compile-time checking. I'll find issues that way faster than using the preview pane. The preview pane can be nice for initial layout, but I use the Hierarchy Viewer for figuring out why my layouts don't look right.
It really depends on what type of project it is, or piece of a project, and what type of programmer you are. Some people just prefer pure code, while others like leaning as much on other tools for design as possible.
XML definitely has some benefits, like being able to switch between interface designs quickly. For specific design themes that are repetitive, is definitely useful for most programmers.
I personally prefer doing everything programmatically, and it is quicker for me to develop than writing XML, with the libraries and classes I have created. XML is quicker straight out of the box.
As for performance, there really isn't a difference worth mentioning unless you are using the same view so repetitively, at the same time, to the point that it no longer fits on the screen many fold. I did a test of how many text views Android could render on a Moto X - Android 4.4, and it couldn't get much over 5000, but there is never a purpose for that. If you are at that point, you are either need to dynamically load and unload data or are just doing something very wrong to begin with.
So learn both sides of it, definitely get to know the pros and cons with your style of programming, because there is no right answer for everyone, and let loose and have fun.
It is much better to separate the layout and put it in the xml file. I occasionally have to adjust the layout in code, but it is always an exception and only when I determine that it cannot be done in the layout .xml. If you use the layout views correctly, the application should look very similar on all devices.
I'm currently reading books and articles about Test Driven Development, both in the case of Android development and about TDD in general. I'm a bit confused about testing the GUI.
In this book the author writes test even for designing the GUI for an example application. For things like "an EditText's margin should be 5 pixels wide". Does this really make sense? I can understand the value in writing test for specific functions (e.g. does my unit converter app convert 5 meters correctly into inches?), but should I really test if I defined my UI widgets correctly in the layout xml file?
I usually have to develop UIs that are much more complex than the 2-EditTexts-below-each-other scenario. I think it'd be a complete waste of time to write tests to check if I defined the font sizes to be 22dip or not. Am I getting the wrong idea?
Test what you think can break. If you don't think the EditText's margin will ever change - don't worry about it. But think about the ways it could change. Beyond the obvious one of changing the value in the XML, you might decide for the sake of simplicity, consistency, and reduced line count that you want to use styles and themes. Now that individual element's margin can change because its theme changed - or because the theme on which it was based changed, etc.
I think you're right; it sounds like the book (which I haven't read) is choosing a toy example, perhaps for pedagogic clarity. Extending that example to real projects without applying a little common sense adjustment may be inappropriate.
I've been through the Android tutorials - these do a good job of introducing how we can hand-roll an Android user-interface. Actually, I do not need that level of control right now... I'm looking for something simpler...
I'd like to make an Android app which will mainly contain a number of standard UI widgets, nothing particularly fancy. Having done some VB development a long time ago (yes, I know it's crap!) - I particularly like the ability to paint user-interfaces with an interface designer and then add in the relevant callbacks via the IDE. I'm using Eclipse, so for now solutions requiring net-beans or other IDEs are not particularly helpful.
I'm well aware that this practice often produces sub-optimal code, and less than beautiful interfaces. That's not really a concern here. I just need to produce a certain effect quickly in order to prove a concept. There will be plenty of time later on for optimization if my idea is good enough.
If you create a layout xml file you get "drag/drop" for the activity layout. It's not perfect, but you should be able to accomplish what you're asking for.
How you were used to VB development won't work out for you.
You will have to create your interface in XML, and put events to the objects by code. There is DroidDraw but it won't get you further then the plain inbuilt IDE of Eclipse.
When creating XML layouts think like it a HTML layout, nested objects, tables/linearlayouts etc...