in my Android app I need to select data from a SQLite database. However, I have a search field in which users can type the name of a location. As they may typo this name, I need to be able to draw the relevant records from the database according to this.
For example:
Input: Ferris Whrrl
Actual: Ferris Wheel
It should locate the Ferris Wheel entry correctly despite the typo. I realise that editdist3 is not implemented in Android SQLite. I'd also rather not select the entire database into RAM and loop through all Strings and calculate Levenshtein distance manually as this would be super resource intensive.
Any help will be greatly appreciated!! :)
I think the best thing you can do is to implement an Auto Suggestion function just like all search engines nowadays do.
You could implement a dynamic algorithm that searches and caches values as needed when a new letter is entered. However, if you just operate on the bare metal without the help of any external service you will have resource problems too - depending on the size of your database and other context variables.
Having a proper index will help but I still think to load the all necessary values into an array and search is faster.
Here you need to create an AI system to guess the correct word. I think this is not relevant to SQL or Android.
Or you can use online AI system to guess the correct word.
Related
I have a SQLite database which has a table (of course) named Object. In my application, I need to access that table and all of its fields. I am able to query the database and get all of the information I want from a cursor with no issues. The problem comes with deciding what to do with the cursor next. Right now I am thinking of creating a class called Object and it will have fields for every column in the table which will be set by the query. This just seems so... inefficient. I'm not sure how to do this without needing to write out every column that is in the table for the object to use, which seems to violate DRY. Are there any better ways to do this?
My end goal is to be able to access every row in the table and get whatever information I want for that row. For example I will be using this to populate a ListView. If this is too ambiguous let me know and I'll try to clarify.
Thanks!
Edit: I've found the library db40 and it seems to do what I want. The library seems to be kind of big though (40 mb) for a mobile application. Does anybody have experience with this? Everything I've read seems to indicate it is good. I'll post more if I find information.
Are there any better ways to do this?
This is very "wide" question and depends on personal requirements and what is for developer more comfortable. I'm using your idea that is for me the best one you can use.
Generally we can say you want to create ORM (object-relation mapping). It's very clean and efficient approach (my opinion). Of course sometimes is not the best solution to use ORM ( i never met with this case but heard about it). I almost always use my own defined ORM for sure it takes some time but results are significant against done frameworks.
Both have advantages and disadvantages. Own ORM has much more higher performance because it's designated and optimized for concrete solution (mainly queries etc.).
I suggest you to do what you mentioned -> create object that will represent table in database with properties equal to columns. I'm using this in work and we never had problems with performance or too much battery consumption with our applications.
It's also much more safe if you'll show user some data not directly from database but "copies" in objects. Users can do whatever want with dislayed results (they can add some dangerous symbols and hacks) but now you can easily check this before you'll want to update database(s) with changes.
Your source-code looks good, another developer won't be lost in your code, everything will be clear and easy to do updates for future.
I provided you "my opinion" on this thing so hope it'll help you with make a decision.
I am developing a glossary using the sample code Searchable Dictionary. Thanks to searching here, I have figured out how to update the database, which is a .txt file, and then get it to load by changing the version number in Dictionary.java.
My question is, how to do the following:
I would like to be able to insert illustrative images into the definitions.
I would also like to insert links to other entries in the dictionary (e.g. 'inventory' should have a link to 'product flow' and other related terms).
I would also like to know how to insert a carriage return.
My original glossary in spreadsheet format has several fields: 'term' 'definition' 'example' 'related terms'. I want to be able to put in links and images inside these fields and have a couple of carriage returns in between each field to differentiate them.
The dictionary code seems to take in everything as a string, so even if I try to put 'image.jpg', or '\n' for a new line, it simply prints that as part of the string. Is there a way around this?
Searching stackoverflow gave a few links to using SQLite. I am honestly a newbie at all this; the last time I programmed anything significant was ten years ago. Rewriting the code to directly access a SQLite database would be nontrivial for me. So I would like to know if that is really the route I should be taking. If it is, then could you point me to the most simple tutorials for constructing a dictionary that way? I downloaded SQLite data browser, but haven't figured out how to use to construct a new database. I know it should not be so hard; I just don't know what I am doing. :(
If there is an easy way to just do it inline, still using the Searchable Dictionary sample code as a base, that would really make my day. Otherwise, any specific suggestions/directions would be really appreciated.
Thank you!!
Update:
For clarification, below is an example of one entry in my glossary, as desired. There are carriage returns between sections, and links and images are inline with text:
Heijunka, or Load Leveling - An approach to smooth production flow when a mix of products is to be produced, by identifying for a selected time period, the smallest batch size at which to produce each specific product in the mix, before switching over to make another product in the mix.
Example:
Keeping a steady work flow, even if much slower than the original max, reduces waste (<-this is a link to the entry 'waste' in the glossary):
[image of line of balance graph with load leveling, and without]
Related Terms: work structure, demand leveling (<-These are links to respective entries)
Not sure if you saw this already, but Android has some developer lessons for saving Key-Value sets for simple data, and saving to SQLlite for more complex structures.
It sounds like your app needs a database called "Invetory" with the following fields: "ProductImage", "ProductTitle", "ProductLink". And you want to store the image as a BLOB. There's a good SO post on how to take an image from a URL and convert it to a byte array for storage: how to store Image as blob in Sqlite & how to retrieve it?
For the carriage return, i'm assuming you're using "\n"? If that's not working have you tried unescaping your string for TextView:
String s = unescape(stringFromDatabase)
Or for SQLlite:
DatabaseUtils.sqlEscapeString()
Key-value data: http://developer.android.com/training/basics/data-storage/shared-preferences.html
SQLlite data: http://developer.android.com/training/basics/data-storage/databases.html
Additional SQLite resources:
http://www.youtube.com/watch?v=G8ZRXdztESU
http://www.vogella.com/articles/AndroidSQLite/article.html
I'm looking for the best way to find a random English word using an Android app. Is there a better way than saving a .txt file with all the words in your res/ folder, such as
http://www.stanford.edu/class/cs106l/assignments/dictionary.txt
then importing it into an ArrayList? The app I'm developing will search for words quite often, such as a random word starting with the letters 'A' or 'Be'. I'm worried about memory and runtime with this function.
Create a SQLite database containing all the words. You can then query that database using SQL to match your random word with various starting letters.
SQLite Details: http://developer.android.com/reference/android/database/sqlite/package-summary.html
Look for documentation on using LIKE in SQL for your text matching.
Example: http://www.techonthenet.com/sql/like.php
For randomness, find all words matching your criteria. Get the count of them (call it 'n'), then pick a random number 'x' between 1 and n, and take the xth record.
Use a prefix tree (or Trie) as described here.
It's extremly efficient, as all word-beginnings are only stored once.
Background:
My CSS360 group is attempting to create an Android application that will include an auto-complete search feature. The data that we'll be searching consists of around 7000 entries, and will be stored in a SQLite database on the phone itself. The most obvious approach would be to do a linear search of the database following every character that the user types, and then return a list of suggestions which are potential alphabetic extensions of the user's query. However, this seems like it would be pretty inefficient, and we've been looking for better alternatives. In another one of my classes today, my instructor briefly discussed the trie data structure, and mentioned that it's often used to store entire dictionaries. Entries into a trie can be retrieved in logarithmic time (as opposed to linear time for a regular old array), so this seems like a great tool for us to use! Unfortunately, we're in waaaay over our heads on this project already, and none of us really have a clue how to make this happen. All any of us have ever coded to date are basic console applications to teach us programming basics. We're all attempting to learn the Android platform in a week's time by watching YouTube videos, and differing the database stuff to the one guy in our group who has any SQL experience whatsoever. We could seriously use some pointers!
Questions:
When creating a trie, is it possible to have the entire structure pre-populated? IE: generate a line of code for every node used, so that the entire structure will already be in memory when the program starts? My thinking here is that this will save us the overhead of having to regenerate the entire trie from the database every time the program starts. If so, is there an easy way to get these thousands of lines of code into our program? IE: Some sort of script which converts the database files into a giant text file of java commands which can be copied and pasted into Eclipse?
Will there be a considerable amount of overhead if we search the database directly instead of using some sort of internal list or data structure? Should we be copying the names out of the database and searching them inside the program for our auto-complete function?
If this proves too technically difficult for us, and we have to resort to a regular linear search, will the performance be noticeably affected?
Our current plans are to run the auto-complete function each time the user enters a character, and then wait for the function to return before allowing them to continue typing. The only programs any of us have written so far function synchronously like this. What would we need to know to make this function asynchronously? Considering our novice abilities, and the requirements that we're already having to meet, would this be too technically challenging for us?
sqlite should be able to serve this auto-complete functionality reasonably well. I'd recommend using their internal indexes over re-implementing the wheel. If you need to do the latter, then sqlite is probably not going to help you after you've done that work.
If you want substring searching, then full text search is probably your best bet.
If you only want to complete the beginning of the word, then just using their vanilla indexes should be more than enough. If performance is a problem, then just wait until they type three characters before doing the query. Set a limit on your results for snappy responses.
I want to store structure type data (i.e. information of call logs like name, number, type of number, date, time, duration). Which is the best way and which is faster? SQLiteDatabase (make table and insert, delete logs in it) or use file storage (means make one class for all parameters and write their objects in file using input/output Stream and serializable) or the another way i heard about it is XML parser but i don't know this.
Please help me. Thanks in advance.
It depends on what you are trying to do.
If your goal is speed, the SQLite will give you a serious run for your money (especially if you wrap multiple inserts into transactions). SQLite has been optimized for everything you mentioned and it would be very easy to leverage the speed it can give you.
If portability is your goal, then files may be a slight bit easier. Files can be moved back and forth very easily easily, whereas SQLite might take some more effort.
If being able to search is your goal, then you'd be a fool not to use SQLite, as it is extremely good at searching and filtering results.
I can't give a very informed answer here because I'm just as new to the subject as you are, but here is the link from the developers page that goes over the different types of data storage. I hope you find it useful. http://developer.android.com/guide/topics/data/data-storage.html
Personally, given you know the basics of Databases I would use a sqlite database. It's pretty straight forward in Android. In terms of speed I don't know which is faster, but if you don't have millions of datasets it won't matter.
In my experience in most cases JSON in a file is enough (mostly you need to store an array or an object or just a single number or string). I rarely need SQLite (which needs more time for setting it up and using it).