Android :: SQLiteOpenHelper Documentation Not Clear
Jul 9, 2010
The documentation does not make the interation between onUpgrade() and onCreate() clear.
When implementing onCreate() should this create the database at version 1, assuming that onUpgrade will apply all of the patches to bring it up to version x (lets say version 5 for example)? Or should onCreate build the latest version of the database, and onUpgrade is only used to upgrade legacy clients.
I kind of prefer the first, because it effectively means that the same SQL is executed for everybody. Whereas the second options means that there is a potential for onCreate to build something slightly different to the succession of patches built by onUpgrade.
I can always make onCreate call into onUpgrade, however, this is the kind of implementation detail that should go into the javadocs...
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Jul 21, 2010
Do I need an instance of my SQLiteOpenHelper class for each Activity I have? I have 1 currently that all activities access, but started getting an exception
"illegal state exception SQLiteDatabase created and never closed "
on simple a simple query and I can't seem to figure out why this is happening. I read online about this, and wanted to try to understand why the SQLiteOpenHelper was dependent on an Activity.
Is there a way to just have open SQLiteDatabase object without the Helper and have it just exist within all activities?
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Sep 10, 2009
I get a SQLiteException if I try to issue an alter statement in the onUpgrade method of SQLiteOpenHelper subclass:
Can't upgrade read-only database from version X to Y: /path/to/db
That makes no sense at all! Where did I go wrong?
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Feb 11, 2010
I would like to know if it is possible to have several DbOpenHelper in the same app Android but to use them to write and read in the same database? because I'm trying to create tables from 2 different OpenHelper (with different names) and only the first one seems to create. when I try to run the 2nd one, i get an error...
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Jun 9, 2010
I have a SQLite database, and several tables within that datbase. I am developing a DBAdapter for each table within the database. (reference Reto Meier's Professional Android 2 Application Development, Listing 7.1).
I am using the adb shell to interface with the database from the command line and see that the database is being populated as I expect. Occasionally, I want to drop a table so that I can ensure it's being built properly, from scratch.
The problem is that SQLiteOpenHelper only checks to see if the database exists. Is there a typical solution to writing a helper to also see that the table(s) exists? Basically once I drop a table, the helper checks to see that the database exists and assumes all is well.
Also, the CREATE_DATABASE string used in the reference above only creates the one table. Should I consider using the DBAdapter for an adapter to ALL of my tables? That doesn't seem as clean to me.
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Aug 17, 2010
I am doing my first app with a database and I am having a little trouble understanding the onUpgrade function. My database has a table with an items and a favorite column so that the user can favorite an item. Most implementations I see simply drop the table and reconstruct it but I don't want to do this. I want to be able to add more items to the table.
When the app is upgraded through the android marketplace does the database know its version number? So could I increment the version number in the code and then export it to the marketplace and when the user boots up the upgraded version for the first time then onUpgrade will be called?
If this is the case my onUpgrade would simply pull from a file and add the database items in. Is this a standard way of doing things or is there a better way of handling this in Android. I am trying to stay as standard as possible.
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May 21, 2010
If you extend SQLiteOpenHelper, for the Constructor you have to use a Context. I am wondering if there is a way to leave this out, and be able to work with database tables without a Context.
Or at least be least restrictive, I mean a way of project/class structure that will make history the several context passings I have to do now.
As it is my application has several level of classes, chained in each other, and there are a few that connects to the database, but have no whatsoever influence on the interface, so they don't actually need the Context.
Are you creating your classes in the way that you pass each time a Context to them?
If not, how you do, how you reuse a Context in a short class?
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Jun 11, 2010
The documentation describes the class as a helper object to create, open, and/or manage a database. Having that in mind wouldn't you say that the name is a little misleading?
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Sep 13, 2010
Every time i increase my database version and push the upgraded app to the users, something weird happens.. For some it works perfectly fine, and some report crashes (including through the Market's reporting system) caused by the lack of table columns i just added in onUpgrade.
If you want to see the method:
http://code.google.com/p/tag-todo-list/source/browse/trunk/Donut/src/com/android/todo/data/ToDoDB.java#136
I can't spot any exceptions that appear in onUpgrade. What i'm currently doing to bypass these problems is intercepting the exceptions where the new fields are invoked for the first time and then calling onUpgrade 'manually', which is kind of dirty.
Also, the app sometimes generates a 'no such table' SQLiteException when accessing the main table (again, only for some users) which is incredibly strange... Does someone know why these things happen? Or can you spot something wrong in my code?
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Jun 9, 2010
I have an existing SQLite database file from another project.
Where do I include the database file into my Eclipse project to have it deploy with the app.
Do I need to indicate that the database file is writable? (In the iPhone world you need to copy the database file from the app's bundle to a writable folder on the iPhone proper before first use.)
Once I have the database file on the phone, how do I tell SQLiteOpenHelper to use it? (I extend SQLiteOpenHelper in a custom class.
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Oct 17, 2010
How can I emulate an onUpgrade call for my SQLiteOpenHelper class? I have tried changing the version number in my SQLiteOpenHelper class and versionCode in manifest but onUpgrade is not called. Any idea? I need to check my onUpgrade code before upload it to the market, I don't want my app's users get a buggy upgrade.
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Aug 24, 2010
I'm trying to implement a database in my application. I'm following a tutorial about writing my own ContentProvider, but I'm confused about SQLiteOpenHelper::getType. We're supposed to write it and, essentially, write a switch that returns the MIME type corresponding to the type of data we're dealing with.
I don't fully understand it. I'm not sure, even though I have an example, what is precisely supposed to be conveyed here. How do I determine the MIME type of my different tables of data?
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Feb 27, 2010
I have two classes, one MainClass and one DataBaseHelper class, which extends SQLiteOpenHelper.
From my MainClass I call a method in the DataBaseHelper class to open a data base. Before opening the data base I want to check the users data base version (this is important as soon as I want to update the data base and push it to the Android market). So from the DataBaseHelper class I call the following method, which is in the MainClass.
CODE:..........
I call the checkCurrentDbVersion() method from the DataBaseHelper class like so:
CODE:.....................
As soon as the debugger runs the following line, it stops.
CODE:...........
I have no constructor defined. Could that be the failure?
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Nov 16, 2009
I've had fine luck using SQLite with straight, direct SQL in Android, but this is the first time I'm wrapping a DB in a ContentProvider. I keep getting a null pointer exception when calling getWritableDatabase() or getReadableDatabase().
Is this just a stupid mistake I've made with initializations in my code or is there a bigger issue?
CODE:.........
But here's LogCat showing the exception:
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Jun 24, 2010
What exactly does HTC Sense Clear Data actually clear? That may be a solution to reverting back to 5 homescreen pages instead of 7 without having to do a factory reset. Just curious as to what I am going to mess up? Will i just have to personalize the homescreen again, put widgets up, reconnect to fb, twitter, myfaves, etc. It's not going remove any 3rd party apps, just make me create new widgets, etc..?
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Nov 9, 2009
Is there any documentation on the Dev Tools app that is incorporated into the AVDs?
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May 1, 2009
I noticed WebView seemed to have some new methods I didn't remember from before. Unfortunately I can't tell exactly which ones are new, without actually trying them and waiting for the SDK to catch the mistake.Could the docs please state in which API release a method, class, interface, enum etc was added? This is pretty fundamental to know when trying to figure out how to implement something.
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Jun 11, 2010
Where can i find the ddmlib javadoc or sources? I was browsing through the android git repository but was not able to find the corresponding project.
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Apr 29, 2010
I'm using Eclipse with the Android SDK. I installed The SDK platform Android 1.6, API 4 using Android SDK and AVD manager, but I can't find the corresponding documentation in the list of the available packages (there's only the doc for the API 7). Where can I find it?
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Oct 6, 2009
I have been using the Android documentation for a few days now, and it is quite good and easy to read. Apart from that I noticed that I missed something, and now I found out what it is: Examples and comments.
If you look at the PHP documentation (e.g. http://www.php.net/manual/en/function.substr.php for the PHP substr() function) you will see many syntax-highlighted examples and comments by users.
Of course there are examples in the Android documentation, especially in the Dev Guide category - they just are not at the right place if one searches the reference for a specific method or functionality. What do you think about this?
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Mar 21, 2010
Does anyone know if there is documentation explaining the SMS content provider?
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Jul 20, 2009
A small notice here to say I found an error in the documentation, when building a radio button context menu in XML.
On this page, in the Menus section, under 'Elements and Attributes' for the <group> tag. http://developer.android.com/guide/topics/resources/available-resourc...
"checkableBehavior - Whether the items are checkable. Valid values: none, all (exclusive / radio buttons), single (non-exclusive / checkboxes)"
This should actually be the other way round: * all (non-exclusive / checkboxes) * single (exclusive / radio buttons)
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May 12, 2010
I am Graduating in Computing Science, and my final project is a complete research in Android's Platform, with a development of an application. I would like to know how can I get the complete documentation, beacause my research is very thorough, and I relly on books and documentation. The current site I am reading about methods and activities, etc is the Dev Guide on developer.android.com. I don't know if is it complete there. But if you know, could you please show me the link, or tell me how to get it?
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Nov 20, 2010
My app uses two databases (separate files). To handle these databases I have created two Helper classes which extend SQLiteOpenHelper, one for each database.
I am now going to add a third database and wonder whether I need to create yet another Helper class (and if I used a 4th and a 5th database would I need even more Helper classes), or can I use the same Helper class for multiple databases?
The problem that I see with trying to use just one Helper class is that I can't see how to pass the name of the individual database files to the Helper. At present the name of the database is hard-coded as a Static field of each of the Helper classes, but if I had only one Helper class I would need to be able to pass the different names in to the Constructor when creating the separate Helper objects; the problem is that the SQLiteOpenHelper Constructor seems to be called by Android with just one parameter: the Context.
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Jun 23, 2010
I'm trying to find some official android documentation that discusses sleep mode, with a focus on issues that might be of relevance to app developers. For example, things like:
1. What causes a device to enter / exit sleep mode?
2. How are running processes impacted when the device enters sleep mode? (I believe they continue to exist, but don't execute because cpu activity is suspended. When the device wakes up execution picks up where it left off?)
There is some good info in the API docs for PowerManager and WakeLock, but nothing there that explicitly states what I have assumed in point 2 above. Are the above issues (and any other relevant issues) documented anywhere?
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Jul 24, 2009
Is there a poster showing all the class and methodes offered by the android SDK and their inter dependence?
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Aug 26, 2009
I was thinking, wouldn't it be great if all the android reference documentation was in the pages section of this Google Group, i.e. stick everything in here:
http://developer.android.com/reference/packages.html
In here: [url]
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Oct 6, 2009
Can someone point me where the documentation of window manager is present?
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Apr 8, 2010
I've been looking around for this for a long time but can never seem to find it in the Android documentation. There's all sorts of advanced things I see, but I can never find any solid documentation - there's the shapes package, but it provides no insight on how to use them in xml. The best I can do so far is finding other people's examples.
Is there some magical documentation that exists for the XML shapes?
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Feb 10, 2010
Does anyone know how to integrate with the new Gallery3D app (cooliris android gallery)? I want to launch that app so it shows the thumbnails for only a specific folder.
For example, say my app downloads images from my server and stores them in a folder on the sd-card (/sdcard/myapp/image-cache/someid/*). I'd like to be able to do something like the following:
CODE:...........................
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