Android : Best Practices To Be Followed When Designing Database?
Aug 30, 2010
I have to create a number of tables for caching some amount of textual data, obtained by reading XMLs. These tables need to be created only once - on the initial run of the application. The data in the tables should be cleared after fixed time period. There should be a class exposed to other classes that would allow CRUD operations on this database. Googling found me some links to tutorials for creating databases and Data Access logic.
I have some questions, please help:
How many DataBaseHelper(DBAdapter) classes should I have, I am guessing only one? Is it okay to have all the SQL DDL and DML statements, DB name, Table Names as static strings of this class?
How do I ensure that the tables are created only once?
Is it possible to clear the DataBase after a fixed time interval?
Are there any best practices to be followed when designing the database?
The data in the database is to be displayed in Lists. I have data in ArrayLists(created when parsing XML) as well as Database(after these lists are persisted). What adapter should I use to back the list up? Should I use ListAdapter or CursorAdapter?
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Sep 2, 2010
I have a small doubt, Which is the best way to design UI for Android Coding or Desinging in XML? Which is better in performance?
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Aug 24, 2010
All the example codes, tutorials or video I see, there is always one ContentProvider per SQL Table with the SQLiteOpenHelper extension defined as a private static class... Is it some sort of standard design...to have one ContentProvider per SQL Table? Or I can define one generic ContentProvider and use its instance for ever update? Is there some issue with that? Could anyone please help as my application has like 5-6 tables.
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Jun 27, 2010
Does anyone have any good references for designing and implementing an idea I have for an android application. My idea is for an application that stores information and reviews about a specific location and presents this information to user.I have gone through all the tutorials and have been reading up on anything and everything about android. Now I am ready to challenge myself with my first app.
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Mar 3, 2010
I am facing a problem in designing LinearLayout. What I want is the Textbox at the top and button bar at the bottom. But the top Textbox just don't appear. The xml file looks like this:........................
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Jan 5, 2010
I need to design a board UI using android platform. I was planning to take one image as board and moving the required images over the board. How do I achieve the same? I need to find the coordinates for image and need to move the required images to specifies coordinates. Is there any andorid API for this?
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May 25, 2014
Eclipse has provided us with different qualifiers like size, ratio , etc. So when I select a qualifier, it provides us with the right emulator screen to make our layout. But are these emulators screen loaded under the right layout folder? I dont understand, how Nexus 10 which is a xlarge screen size is loaded when I load the activity_main under the Normal layout folder?
am I blindly arranging these layouts? Because before this, I had arranged all layouts perfectly and when I went to run it on a Virtual Device, it looked a complete mess. I looked at the xml files and they were completely in the wrong places.
I have used qualifiers like : normal-long, normal-notlong, large-long, large-notlong, small-long, small-notlong, xlarge-long, xlarge-notlong,Should I change the qualifiers?
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Oct 26, 2009
The idea is to allow users to download a skin packet from the android market and be able to change the skin via the main application.I assume this skin pack would contain only the layouts and res names that I would want to overwrite from the main application. How could I approach such project?
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Jun 27, 2010
Does anyone have any good references for designing and implementing an idea I have for an android application.
My idea is for an application that stores information and reviews about a specific location and presents this information to user.
I have gone through all the tutorials and have been reading up on anything and everything about android. Now I am ready to challenge myself with my first app.
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Jan 14, 2010
How would you go about designing a system based on arbritary zones? Think of the American states - basically the whole map is carved up into irregular zones. Then again another one might show a salesmans territory, TV stations coverage area etc. I need to be able to retrieve the current GPS position and determine which zone I'm in. I can't use an address/zip lookup - its purely based on the lat/long point. So the data structures which define the enclosing boundaries must be flexible enough to provide fairly accurate positioning. As a bonus, I'd also like to be able to render these zones on the map, maybe with different colors. Any tips/pointers to anything close to this would be very welcome, thanks.
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Jun 30, 2010
I'm using Relative layout for designing UI. Please give me guidelines to follow.
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Jun 2, 2010
I am trying to learn how to do stuff in Android, and I'm not sure of the best way to build the interface.I've been working on porting an iPhone app, which uses navigation controllers and table views for looking at the different sections: basically, someone touches a cell in the table, which drills down to another table. when they touch a cell on that table it drills down to a webview that displays the information.I want to do something similar for the android app, but I don't know how, or if there is a better way native to Android. I've figured out how to use the webview to my purposes, but moving forward and backward in the table tree is unclear.
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Nov 3, 2009
What is the best way to use the MediaPlayer when needed multiple times?
Reuse the instantiated MediaPlayer throughout the session? Or constantly stop() release() and instantiate a new MediaPlayer() ?
If I reuse I'm afraid the player could be in a bad state? What about performance wise? what's better? reuse or renew?
This is for using as a music player so one audio be present at one given time...
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Sep 29, 2010
I never do graphics type programming. I'm designing a screen that will need to look good on all phones, and all resolutions. It's for displaying in a list view, and there will be a small graphic for the summary view, and a larger graphic for the detail view. Normally I use a 32x32 (res 72x72ppi).png for the summary view which looks good on my G1. The second image is for the detail view and it basically should fill the entire width of the screen (roughly, it's ok if it doesn't use the entire width as long as none of it is chopped off). The size I use for my G1 is 468x60.
So, the question for the guys that really know this stuff is: What sizes do I need to make these images to support all screens and densities with the fewest number of images? I know that the answer is a little subjective, but I remember seeing a post with a link to a page that recommended 3 different images for the different screens (and it seemed to make sense when I read it), and I think but don't remember for sure that then you would need 6 layouts to support those with both landscape and portrait orientations.
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Jan 17, 2010
What is the best (meaning: most popular) UI Java markup language for designing applications for Google Android?
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Apr 27, 2010
I am building and designing a (mostly) read-only interface to some data. I'll be uing ASP.NET MVC to build a psudo-restful API. I'm wondering if anyone can provide some resources for building full-client applications for various mobile platforms, iPhone, Android, Blackberry, Windows Mobile, etc. I'm thinking that serving up XML data is going to be the most simple and universal, but parsing XML in objective-C for example doesn't sound like fun to me, but maybe there are some good libaries out there to help ease this task?
In other words, what formt will be the quickest to implement on the client side? Are there any JSON parsrs for iPhone or Android? I know there are .NET JSON parsers, but not sure about other platforms -- is ther another format that might better? Or should I stick with pure XML and deal with it on each platform differently?
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Jul 18, 2010
I am going camping next week and need a application for tracking while running. I would like to design my routes online (in google maps or other mapping service) and then use an application for displaying these while running. Anyone knowing such a service/application?
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Jun 26, 2009
My company is in the process of evaluating if we can add support for Android to our product. I am currently working on porting our existing J2ME library to the Android framework and I have a question regarding our UI component. Right now, we have a custom menu that we allow our developers to bring up on the device. On J2ME, we simply have a single call that the developer makes to enter into the menu and then we handle the rest. On Android, it seems the best way to handle this is an Activity. But I have a few questions regarding this approach including is the really the best way to do something like this? Second, if it is, if there are multiple applications on the device that are using our library, are there going to be conflicts with them all having the same Activity embedded in them? Is it possible to create an Actvity at runtime and use it directly? Would there be any side effects of going about it this way?
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Oct 23, 2010
Understanding how to declare activities in the manifest file, how to set the appropriate flags when starting them through intents, is quite challenging in all but the default cases. The combination of all these settings and flags is daunting. I've been developing for Android for over a year now, have read the application fundamentals and the reference guide for 'Intent' quite a few times and still I don't have a good grasp of which manifest settings or intent-flags should be used for starting activities in many situations (workflows). Is there some source/document that can explain certain work-flows (ways of navigation through activities and tasks), that shows examples of how to configure and start activities?
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Sep 10, 2010
can you advice me a book or something else containing good practices about how to build/structure a web application in a way that will be easy to extend it with an Android/iPhone version later.I am currently trying to get into Django so it will be nice if the practices are related to it.
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May 8, 2010
I have an application with several tables, each being updated by AsyncTask fired by different Activities and used by UI with SimpleCursorAdapter. Though i am not developping a game, I would like to avoid to interrupt the user as mush as possible. Has SQLite is not multiaccess proof, what is the best way of handling such situation?
- I consider adding lock from each DB open and to each close sequence but this seems quite subject to bugs - The solution i am using now is that each DB access (read/write) is done in UI thread (when AsyncTask completes, DB write is done typically in onPostExecute), but that means user is blocked for several seconds during the DB write.
Is there any better solution for that? Should i use a ContentProvider? when i read "Content providers store and retrieve data and make it accessible to all applications", this does not seems to be what i need. Any idea?
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Apr 22, 2010
What are the best practices people have used to integrate help/tips in their application? One way I can think of is having html snippets in resources or assets - perhaps as html files - maybe as formatted strings. However, I think it would break down once an html file linked to another html file or an image or icon. I'm sure some of you have apps that are so wonderfully intuitive that they don't need any help. And I admire that. But I'm not making that assumption for my app.
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Nov 12, 2009
My Android app is reading and writing to a local SQLite DB from a few different Activities and a Service. Pretty standard. But I'm not happy with the way I've got all the DB details stored as constants that I then use anywhere I access the DB. I've been advised to wrap the DB in a ContentProvider. Sounds good to me. While I'm refactoring my code, I figured I'd ask: What are your best practices for local DB data storage in Android?
Where and how do you store "CREATE TABLE" statements, column names, other SQL? Would you mind sharing a list of the classes you instantiate and what goes into each (ContentProvider, DatabaseProvider, DatabaseHelper...)? How do you coordinate the structure of your local Android DB with a server-side DB available through a REST interface? I realize I'm getting at the perennial "where's the Android object-relation-mapping framework?" question. For now, I'm mainly curious to hear how you structure your Android apps with what's available in the standard SDK.
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May 20, 2009
I've published an Android applications on the Android market and now have an update to do. I want to know if any of you have already done that, and what experience can you share about it:
- How to manage version conflicts?
- What to do with databases?
- Can you make appear a message with "what's new" if it's an update, but nothing it's a new installation?
- Should you backup old data before updating, and how?
- Did you run into any trouble and how did you solve it?
- Can update be partial (like, just a patch)?
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May 5, 2012
I am using GIMP to create graphics such as buttons and background but don't have a proper understanding of the process. Do I create a background and then layer it with the buttons and then save each layer separately? Do buttons have to be squares or circles or can they be stars for example? Do I need to create every background and button as a 9patch or do I just create 2-3 different resolutions? and finally where do I set things like dp?
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Jul 25, 2010
I am a newbie to Android and the Eclipse development environment and would like some advice on best practices for debugging my apps when they throw a Force Close.I have researched ADB, however, I can not get this to interact with my phone even though I have explicitly turned debug mode to true on my test handset.Obviously Android comes with a LOG method which I have seen utilized in many example apps, can someone please explain how to review these logs quickly and how to setup logging appropriately to determine the cause of a Force Close (always occurs when I push the Home button).Any advice on debugging effectively in Eclipse would be much appreciated!
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Aug 12, 2010
I have a mobile app, which is pretty data driven, though only through text and images. In the current version each click or touch requires pulling new data from the server (appache/php). With network delay this easily takes 1-2 seconds for the first content to appear, which is far too long. I have heard about and considered the following options, but are not sure if some of them might be counter productive, or if I have left something important out?
Download all data from the start, in a big bunch with a loading screen? Run a prefetching thread, predicting and downloading data the user might want, in the background? Keep the connection open to the server at all time? Load different parts of the data in different connections in parallel? (Similar to facebook) Use heavy data compression? A comprehensive article on the matter would also be a good answer.
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Oct 20, 2010
I am working with a ListView, custom adapter and a large number of items. I read in a book for Android that is was more efficient to use what it called the holder pattern. That is to create a wrapper class for each view in the list view that cached the objects in the view so as to avoid calls to findViewById because those are supposed to be expensive. My question is what is better? To have 50,000 objects GC'd every time the user scrolls or to make the 4 or five calls to findViewById per view? Below is my implementation of what the book suggested.
@Override public View getView(int position, View convertView, ViewGroup parent) {
View view = convertView; if (view == null) {
final LayoutInflater inflater = (LayoutInflater)
context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.survey_item, null);
view.setTag(new SurveyItemWrapper(view));
} bindView((SurveyItemWrapper) view.getTag(), position);
return view; } private void bindView(SurveyItemWrapper surveyItemWrapper, int position)
{ final SurveyedItem surveyedItem = surveyedItems.get(position);
surveyItemWrapper.getDescription().setText(surveyedItem.getItemName());
surveyItemWrapper.getCube().setText(String.format("%9.2f", surveyedItem.getCube()));
surveyItemWrapper.getShipping().setText(String.format("%d", surveyedItem.getShipping()));
surveyItemWrapper.getNotShipping().setText(String.format("%d", surveyedItem.getNotShipping()));
} private class SurveyItemWrapper { private TextView description;
private TextView cube; private TextView shipping;
private TextView notShipping; private View view;
public SurveyItemWrapper(View view) { this.view = view;
} public TextView getDescription() {
if (description == null) { description = (TextView) view.findViewById(R.id.SurveyItemDescription); } return description;
} public TextView getCube() { if (cube == null) {
cube = (TextView) view.findViewById(R.id.SurveyItemCube);
} return cube; } public TextView getShipping() {
if (shipping == null) { shipping = (TextView) view.findViewById(R.id.SurveyItemShipping);
} return shipping;} public TextView getNotShipping() {
if (notShipping == null) { notShipping = (TextView) view.findViewById(R.id.SurveyItemNotShipping); } return notShipping; } }
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Aug 26, 2010
I have an activity with multiple list views that are continuously receiving new values form a socket thread, another thread parses the data and updates the array adapters, then the ui thread calls notifyDataSetChanged() to cause the list to refresh.
My issue is that im refreshing all the list a couple of time a second, this causes the UI to be very laggy when some animations need to happen.
I was wondering what the best way is to update multiple lists with multiple value changes every second?
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Nov 6, 2012
My developer does math for matching dimensions between the screens I (the designer) give and the layout she makes. There is a formula for it, but she forgets after a project is over and she has to start all over again. Is there anything I can do as a designer to minimize her head banging hours. Is there a certain formula or layout I should design around to make things a bit easier for her.
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