Hey, I have a lot of Strings that I use into my app, the .txt file that I use has ~14000 lines.. and each 3-10 lines are divided into sections like <String="Chapter I"> ... </String> ..
Speaking of performance/speed, should I put the sections into a Database, Or read line by line through the .txt file and check if the section number is the current one? Will this affect speed/performance?
I could also divide each ~2000 lines into a different .txt file so there would be less lines to go through. Is this a bad way of storing data? Thanks
I think sqlite would do the trick. It will probably be way faster than parsing a text file, plus you wont have to maintain the headache of your own ad hoc text database, or build a parser in the first place. Basically, use it, its way easier.
The standard way to deal with Strings in Android is to put them into res/values/strings.xml (I'm pretty sure you can have multiple String files in that directory if you like). If you are developing in Eclipse it will automatically populate the R class (the resource class) with constants that you can use to reference these Strings in your code:
R.string.mystring
Or in XML layouts:
#string/mystring
Or if you're doing something more custom you can use:
String string = getString(R.string.hello);
I would definitely choose this over a .txt file. It's much easier. All the work is done for you! Have a read of this Android article about it.
This is what a database is for. Use it.
Related
I wanted to read and write specific lines from a CSV file.
Here is an example of my CSV
ID; Code; Name
1; ABHD; Paul
2; HYDR; Arthur
3; POAJ; Jake
4; PLMH; Georges
Actually I know how to read all the file and put it into a list of lines by myFile.readLines().
But I want to read a specific line like the line with the Code ABHD, and later on modify that specific Line without reading and writing the whole file. Any idea ?
Thanks by advance.
A CSV file is a not a database. You can't write individual elements inside the file. You need to read the entire file and write the entire file. If the file is a reasonable size, you can read the entire file into memory, alter the data you want to change (in memory) and then write the entire file again. If the file is huge, you probably need to make your modifications "on the fly" (ie: read a line, (optionally) change it, write the line to the output file).
There are libraries that you can use to parse the data, as CSV can be complicated to parse (especially if it contains text strings).
See https://www.baeldung.com/kotlin/csv-files for some help or search for "kotlin csv parse"
I am working on a project that includes a lot of strings and string arrays. I would like to put them into created folders inside res/values, but I get errors when I try to do this. Either getRecources() does not recognize the new folder or the xml attributes cannot link together. I know this is a noob-ish question, but thanks for the help!
Unfortunately, you can't create any subfolders in your values folder. But you have two instruments to control the hierarchy.
String arrays are declared in the following way:
<string-array name="arr_name">
<item>Text</item>
<item>Another text</item>
</string-array>
You can access them through R.array.arr_name.
Prefixes are kind of obvious, but since you mentioned that you are a novice, it's worth mentioning. I usually prefix all of my strings depending on how they are used. For example, btn_ for the text used on buttons, dialog_ for strings used in dialogs and so on. This way autocomplete in the IDE also works much better too.
Also you can split your declarations into different files, but this doesn't have any impact at all on the way you access them, so I don't know if this can help you.
You can define array of strings using following way. Later you can access it in code with R.values.langs
<string-array name="langs">
<item>бг</item>
<item>en</item>
<item>ру</item>
</string-array>
To organise my res folder I use defined xml files not sub-folders.
Basic Example:
- if you have Strings for your Login Page put them in login_strings.xml
- if you have Strings for your Options Page put them in options_strings.xml
etc.
Hope this helps.
Could somebody tell me what is better in terms of performance?
Is it better to save 2 strings at string.xml, like 'abc' and 'abc:'
Or should I save only the first one and concatenate ':' when needed at Java coding ???
Very difficult to answer depending on what your strings will represent and what you need to append. Localization is also an issue, for example...
Dog // English
Chien // French
Hund // German
Using string resources allows you to create different resource files depending on the locale of the device and Android will automatically use the right localized string resource file. If all you need to do is append a single character such as : then you'll double every string for every language.
If you choose to only save the basic strings and append the character using code, then the code will be universal and you'll simply need to append the character to whatever localized word - potentially a lot more efficient.
Both from storage perspective and performance you should save only "abc";
getting extra data from disk takes far longer as some quick in-memory actions.
storing the same data twice is bad practice in general
If you have to concatenate multiple strings you should use StringBuilder - http://docs.oracle.com/javase/1.5.0/docs/api/java/lang/StringBuilder.html
It's much faster then using '+' or '.concat()'
I wrote a big app with thousands of string in the code.... very bad idea, because now I want to translate each string.... big problem.
Copying all strings to the strings.xml takes a long time.
Eclipse has an option to take all selected strings and put them into messages.properties.
Does this work similiar like strings.xml? When, why all people use strings.xml.
Or should is use eclipse to seperate each string and than I should copy them to string.xml?
All people are using strings.xml because this is the normal way to do it on Android. You don't have to manage the load of the strings, to call any locale function in your script.
You can see the documentation here : http://developer.android.com/guide/topics/resources/index.html
BTW, you can easily transform your eclipse generated file to an strings.xml file after the extraction.
In Eclipse you can use the shortcut keys Alt + Shift A, S to extract an inline string in to the strings.xml file via a popup dialog - might be a bit easier than doing it by hand. And as the others say, yes you should ALWAYS use the strings.xml file so that you only have to look in one place when you want to change a string, instead of having to search through all your code.
I have some reference data in a text file (~5MB) that I want to use with might android application.
The file is of the format:
1|a|This is line 1a
1|b|This is line 1b
2|a|This is line 2a
2|b|This is line 2b
2|c|This is line 2c
What I want to know is the most efficient way (less memory, fast, size etc.) to use this file within my application.
a.) Should I save the file as a raw resource and open and read the whole file whenever I need a certain line.
b.) Should I convert the file to XML and use XPath to query the file when ever I need to look up a value
<!--sample XML -->
<data>
<line number="1">
<entry name="a">This is line 1 a</entry>
</line>
</data>
c.) Should I just copy & paste the whole file as a static string array in the application and use that.
... any other suggestions are welcome.
[EDIT]
I will also need to search this file and jump to arbitrary keywords e.g. "line 1a".
XML will always take longer to read than simple text or CSV files. What XML gives you in the tradeoff is a highly structured and reliable way of storing and retrieving data. XML files are, as you can see in the examples above, a good 2-3x larger than the data they actually contain.
If you're sure that you're never going to run into the "delimiter" character in your simple text file, then that would probably work just fine, purely from a file speed perspective.
You have not provided enough information to answer this question. However, if I were a betting man, the answer is probably "none of the above".
I will also need to search this file
What does this mean? You are searching by some string key? By some regular expression? By a SQL-style query string where certain portions of a line are interpreted as integers versus strings versus something else? By a Google search-style string?
Each of those answers probably dictates a different technology for storing this information.
I will also need to...jump to arbitrary lines.
Why? How are you determining which "arbitrary lines" you are "jump"ing to: key? line number? byte offset? search results? something else?
And, of course, there are other questions, like:
How often is this data updated?
How is this data updated: new version of the app? download the whole file? download deltas/diffs? something else?
Is the data ASCII? UTF-8? Something else?
and so on.
Something that size that must be searched upon suggests "use a SQLite database", but some of the other answers might steer away from that solution.
If you are talking about very small amounts of data, the Android XML compiler can produce very efficient binary representations for you that you can access just like XML. On the other hand if the data is very large at all, and you need arbitrary queries, I would expect SQLlite to win out on performance (as well as flexibility). A small benchmark should be easy to write and would give you a good idea as to the basic tradeoffs involved.
Flat-files would be a last option, imo, but could work if the file isn't very large.
If you define efficiency as (less memory, fast, size etc.), a flat or delimited file will be faster to load and save.
However, people use XML because they are willing to trade some of that speed for XML's greater flexibility and ease of use.