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.
Related
I am a junior developer and I am somewhat puzzled about writing xml layout files.
There are many implementations for the UI layout of the same style, RelativeLayout, LinearLayout, RelativeLayout And Linearlayout, and so on. Different implementations have different nesting levels. We know that there are as few nesting levels as possible, and that LinearLayout is used instead of RelativeLayout for the same number of layers.
But careful analysis, how do we measure the A implementation of a layout is better than B, two layers of nested LinearLayout really do not have a RelativeLayout to save performance? How to determine this? By experience? But where does the experience come from? It may be a good way to read the source code, but it is more difficult.
I think it is possible to find a good way of writing by analyzing the rendering time of an xml layout file and comparing the time spent on different implementations.
So I would like to ask everyone, is this a feasible way?
I'm not sure about, how we check the rendering time. But check below URL's one after one it may help you to understand more about rendering and performance related.
1) https://medium.com/#elifbon/android-application-performance-step-1-rendering-ba820653ad3
2) http://adavis.info/2015/03/android-overdraw-what-is-it-and-why-should-you-care.html
If i find any way to check the rendering time surely will let you know.
I am very new to Android development and, while I get the general premise (and have even built a small application), I have been looking at other developer's source code to get an idea of how to better approach my development for larger projects.
One developer's code is read is basically using both XML layouts and Views for the various parts to the UI (similar to what is being asked in this question). I understand what he is doing, but it seems overly complicated to me. The XML layouts provide functionality already to create responses to actions. (For example, "onClick" is provided for most components in the XML.) Layouts can be generated very easily with the XML.
So, my question is - can I get away with building my entire application using just Activities and XML layouts? Can I choose not to use any Views? (Of course, this is assuming a relatively simple app - think task list or something similar.) Or, am I trying to simplify too much?
The general strategy I use is to push as much as possible into XML. It's a very different way of thinking from some other UI development systems, but it's very cool once you get past the learning curve.
I don't know what you mean by choosing "not to use any Views". Every UI component is a View of some sort. If you mean not using any custom View subclasses, then yes, it is definitely possible. The only reason to create your own custom View classes (and then use them in XML!) is when the stock widgets and views don't do what you want. Since they are quite flexible, this tends to be fairly uncommon (until you start getting into fancy behavior or need custom graphics behavior).
There are two ways for Creating UI for Android Application. They are
Using XML - You can use xml for designing UI targeted for supporting Multiple device. Also XML helps you to create Static components.
Java Code -Generally it's not a good practice to creating UI in java. Its suitable, if you creating a samll application. Its also useful when you want to develop application with dynamic components. If you want to create Dynamic Components in UI, Java code helps you to achieve this.
The Good Approach is to create UI via XML, unless there's no dynamic component needed in the UI. if you need dynamic UI creation then you go custom UI creation i,e., Using Java Code.
Since you are New to Android, i would like you to refer android developer site
I think you misunderstand, XML layouts are just a shortcut for creating views. You end up with the same results at runtime either way. Mix, match, use one or the other, it's up to you.
I will try to keep this short, but I need some advice.
I work on a team that is developing applications for android, iphone, and wp7 in parallel.
We have a design team that comes up with a single design for all three platforms.
The latest application’s design is more marketing than productivity. The original POC for this app was done on the iphone. The design is very animation centric and most state changes are seamless (things will animate on and off the screen during state transitions).
If I keep developing against this design it means I will have to have everything in a single activity. So far, this has been a major headache. To my knowledge, dividing your application into activities is almost required. I could try to dynamically load and unload views as I change states but this doesn’t seem right.
I see where the design team is coming from where they want all these state changes to be seamless, but I don’t think this is right for android.
I would like to know what makes most sense. Should the design change to incorporate multiple activities or would it be worth trying to make this work.
We have a design team that comes up with a single design for all three platforms.
That's akin to coming up with a single floor plan to be applied to apartments, single family homes, and warehouses. The designers, or management, need to have their heads examined.
The latest application’s design is more marketing than productivity.
Did I mention that the designers, or management, need to have their heads examined?
If I keep developing against this design it means I will have to have everything in a single activity.
If I am interpreting your requirements correctly, that is probably accurate. While you can arrange for animations between activities, it is more of a "slide the old off, slide the new on", and I suspect that your requirements exceed that.
To my knowledge, dividing your application into activities is almost required.
It is certainly Android's intended development model for ordinary apps. However, games and the like may not follow this pattern, and you don't have to either.
I could try to dynamically load and unload views as I change states but this doesn’t seem right.
Depending on how many states there are, you might just hang onto all of them, recycling as you go.
I am surprised no one mentioned fragments which can be used instead of activities at many places.
Fragments can be seamlessly animated in and out or an activity.
You might want to take a look at subclassing ActivityGroup for your top-level activity. That can host multiple sub-activities. TabActivity, the only stock subclass of ActivityGroup, is perhaps not what you need because it includes a tab widget, but you can use it as inspiration for what you do need.
What specific headaches are you having with a single-activity architecture? Perhaps there are ways to make that less painful.
In general, if you are aiming to have native apps with a native look and feel, it is not reasonable to have a single UI design for all three platforms. The UI guidelines and user expectations for the systems are different, and those differences should be reflected in the UI designs.
If you really want to have a single UI for all platforms, just create a web app instead.
I'm not sure exactly what you mean by an "animation centric" design with seamless state changes. If you use multiple Activities, Android will animate between them in a way that Android users will expect. If you explain what exactly you are trying to accomplish, we can help you figure out if it makes sense in Android, and if so how to accomplish it.
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.
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...