I have know core java, I want to develop android apps, in few sites I saw apps in XML in few Java.Which is best and easy to use Java or XML?
I'm assuming you are talking about the UI, not the complete app:
For everything statically I use XML, because it is easy to find in the structure of your project.
Some parts you want to create dynamically and you have no other choice then to use Code. Be smart, in this, so if you have to add several Views that look the same do this
Make an XML with your views
In the loop where you are adding the several Views, inflate this xml, set your id's etc, and add them
You can have all the basics, styles etc in your XML, and still add stuff dynamically.
Maybe you want to check out some of the hello world code?
You can't build apps in XML. You use XML to define the UI and a few other things, but the logic of the app itself has to be written in Java.
Android development is in Java, but when you declare the layouts (where the buttons and so are going to be on the screen) you do that in XML.
So you have to use BOTH anyways.
XML for layout
JAVA for programming your app
Related
I have to make a new design for an Android App, but I only have to create the visual part (native Android). The app logic would be created by another guy based on what I present to him.
My question is? How would this be managed correctly? Do I have to make the XML's of each layout? How could I show the other person my progress?
What things should I consider when doing this?
Thanks
You need to mock the app first (create a prototype) as suggested by NoChinDeluxe. Then if you guys go ahead and decide to code it, the answer to your problem is separation of responsibilities. As Jeffrey said UI work is not only about layouts, but code as well. What I would suggest is that you and the other guy get together first and define some contracts (interfaces) that will allow you guys to split the work and work in parallel. Therefore, he can create the business logic of the app without worrying about the UI implementation. You, on the other hand, will have to mock that business logic he's implementing at the beginning so it doesn't block your UI work.
you could create layout XML files for all the Activities/screens, using resources (icons, etc as suggested by #NoChinDeluxe). However since you'd want to run the mock app, you might want to also create a "throw-away" Activity that allows you navigate to different screens of the app. Here you can add a number of buttons and when you click on each button, your app shows a specific activity. This way, you will be able to show your colleague all the screens you have created. I hope this helps.
This may not be what you want to hear, but creating Android layouts isn't a design task. They are closely tied to the code, and the design of them is going to depend on how the engineer chooses to implement the app.
Here's an example. You might have a grid with 4 cells. You could use a RelativeLayout, a LinearLayout, or GridLayout, or a GridViewLayout. Which will use choose?
I'd suggest providing your engineer with mockups and graphical assets where required. Let him / her take those and create the layouts. If you want to create layouts as a (visual-only) reference for engineering, great, but it's certainly a non-optimal tool for that task.
Things You will consider when doing visual part:-
You have to work on the resource folder of your application
Layout : All Layout you have to prepare.
Drawable : Images and drawable .xml.
Inside Values folder you will find
dimen.xml : For different devices dimen you can set.
string.xml : You can store string for hint or other purpose.
style.xml : For designing or theme or custom design.
color.xml : Color which are going to used in the application.
I'm learning to develop android apps and in the process I realized that there two ways to get a job done. Using xml or normal code. Suppose I want to change the position of a button, I'll be doing it in xml using align left/align centre etc., This will be done in the XML file. If I want to achieve the same through code, where should I place the code ? Inside which class ?
There are two aspects to your question that I understand.
1. Creating a whole layout file dynamically (without XML).
2. Creating a layout through XML and changing the components positions and properties dynamically through your activity file.
Now, it's upto the developer what he wishes to choose.
To help you further, please view this video link posted by the Android team.
It's all about layouts and includes how to layout apps using Java, not XML. However, you are warned that the android team wants you to use XML.
The code will be placed in the same class as the class where you reference your xml code. Do a read up in your android docs for insight.
I just started learning Android development and I read there was basically 3 main approaches to 'build a view' which are :
Java-based: Use Java to define Strings, lay out window, create GUI controls, and assign event handlers. Like Swing programming.
XML-based: Use XML files to define Strings, lay out window, create GUI controls, and assign event handlers. The Java method will read the
layout from XML file and pass it to setContentView
Hybrid: Use an XML file to define Strings, lay out window and create GUI controls. Use Java to assign event handlers
What are the benefits and limitations of these 3 different approaches ?
Which one should be rather used by a beginner or a confirmed programmer ?
I'm not asking for subjective answer here ( before being flagged :) ).
There must be some facts that make these approaches different from one another (speed, maintainability, readability...)
XML-based is like using CSS for a webpage. Using XML separates concerns neatly into the MVC (Model-View-Controller) pattern. If everything is specified in XML, then your activity can utilize different layout files for different screens, and the presentation of these elements can easily be updated by just changing to new XML files. This is good software development practice and greatly helps when it comes time to redesign or reuse components. In some cases you may still need to dynamically set some things in Java, but you should try to put all presentation-related stuff in the XML files.
The event handlers should still be set and defined in Java, in my opinion. That is not related to presentation and thus does not belong in the XML files. I do not use the onclick XML attributes. Also, if you set it in the onclick attribute, you can break the connection if you refactor the method name in Java but forget to update the XML file.
The advantage of using XML as much as possible is that all the Android tools provide support for this style of programming (UI editors, etc.). If you do everything in code, you're on your own. (Want to see the effect of a change to your code-based layout? Build your app and run it in the emulator. With an XML-based layout, you can preview it right in the XML editor where you are making the changes.)
Regarding event handlers, the main advantage of declaring them in XML (e.g., with an android:onClick property) is that you don't have to declare the event handler classes. The advantage here, though is not particularly strong, and I often use what you describe as a hybrid approach.
I'd advise beginning Android programmers (whether experienced with other programming or not) to gain a strong foundation in the XML style that Android pushes.
I am very new to Android development and am having some trouble. I am creating an XML file using Eclipse, both the Graphical Layout feature is what I'm having trouble with.
Also, I am working in Android 2.3 for compatibility reasons.
I am wondering if there is a layout which enables me to place buttons or text fields or any attribute where I want to put them. This may sound stupid, but it seems that every layout has some sort of order in which it lets you add attributes, and whenever I try to drag them elsewhere on the layout things just get very very messy.
If what you want is an AbsoluteLayout, this has been deprecated since Android 2 (IIRC). You can try using the RelativeLayout, which let you position freely your widgets. Else, if you only use LinearLayout, then yes the widget will be positioned in a strict way.
use Relative Layout. I recommend that you read up on Android layouts so you understand why, what and hows of Android way. There are some good tutorials that I found helpful. TutsPlus: Android Layouts
There is also a very good video from Marakana.
Marakana: Android Bootcamp
If you are just starting out with Android check other tutorials/videos on Marakana. They are a very good resource for beginners.
I am a complete newb to Android and have seen tutorials that show widgets being added via XML and also via Java. I want to know what industry experts prefer and why. The author/narrator seems to prefer XML saying it gives more control but I wanted to get feedback from veterans.
With XML Tutorial
Without XML Tutorial
Thank You and again I apologize for a complete newb question.
XML layouts are very easy compared to java code. The coding also very less than java.
You can prefer any of these two, but all authors prefer XML because its easy.
Please read information available at this link, you will get an idea.
XML Layouts
Declare UI elements in XML (most
common and preferred)
Android provides a straightforward XML vocabulary
that corresponds to the View classes and subclasses,
such as those for UI controls called widgets
(TextView, Button, etc.) and layouts.
Instantiate layout elements at
runtime (programmatically in Java code)
Your application can create View and ViewGroup
objects (and manipulate their properties)
programmatically (in Java code).
Advantages of : Declaring UI in XML
• Separation of the presentation from the code
that controls its behavior
You can modify UI without having to modify your
source code and recompile
For example, you can create XML layouts for
different screen orientations, different device screen
sizes, and different languages
• Easier to visualize the structure of your UI
(without writing any code)
Easier to design/debug UI
Visualizer tool (like the one in Eclipse IDE)
Advantages of : Instantiate layout elements at runtime
• While showing dynamic data
When your application need to show dynamically some information for example loading title from web then you need as many text-view per title and you are not sure at design time about this at that time this can be preffered
You can make your application design both ways and both will help you the same,It will depened on your requirement whether you require to create it at runtime or not,Anyways I think while you can make separate XML file why need to do it in your Activity java file and get more complexity in code unnecessarily.
XML layout method is very easy, fast and easy to visualize. You can do a paper-pencil work first and simply do it in XML.
XML layouts are easy to manage - you can change the caption, position, look & feel, size, colors etc. in the XML layout, without altering a single line of the Java Code. The App will generate the Java Code for the layout from your XML file.
XML layout does not compell that you should write the whole XML codes. Instead, you can use a GUI editor and you arrange the controls on screen, and it will generate the XML for you. There are lots of GUI design tools. Eg.: http://www.droiddraw.org
Now, you can go for Java Code UI layout only if you cannot determine the layout at the time of writing the App. Say, you are designing an Android App for Web Designers - An app to create HTML Forms and create the HTML code (a simple HTML editor tool), then you are unable to know which type of layout the user is going to do. At this point, the better option is choosing Dynamic Layout (or Java Code layout)
Almost every Android programmer chooses to do layout in XML. That's the beast and easiest way to do it.