Develop Reference

Reading and writing specific line from csv file in Kotlin

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"

Android: Writing to XML file in Assets

I am really lost here, i am trying to find my way around xml parsing, reading and writing.
I have this app where at one point i can input data such as a Date and a time for instance - click save, and once it saved it will write into an existing XML file, for later reading, and add it at the end in a format like this:
<Units>
<item>
<date>27-5-12</date>
<time>15:30</time>
</item>
<item>
... and so on ...
</Units>
i managed to read an xml file, but i am really having trouble in opening a premade - existing file for reading or writing.
currently i tried this code:
InputStream raw = this.getAssets().open("mydata.xml");
Reader is = new BufferedReader(new InputStreamReader(raw, "UTF8"));
which returns file not found exception.
could anyone direct me on what i should look for?
Thanks.

As written, your source XML file is located in your APK's assets directory - everything in your APK is read-only, so you won't be able to write to that file. (Also, you should probably put that XML data into the res/xml directory instead of the assets directory, unless you have a compelling reason to do otherwise.)
If the XML file isn't very long/complex, you could read the assets file into a structure, then add your new data to that structure, and write a new XML file into your app's data directory with the updated data. This approach has the advantage that you can have multiple source files feeding into one main file per app.
A more flexible and open-ended option would be to set up a database table. When the app is first installed, you load/update the table with data from the assets file. As your app keeps adding timestamped data, you just add new rows to the table. This approach also has the advantage that you can easily update the source data or the database structure with each app update - it's harder to compare old vs new data if it's stored internally in XML format.

I didn't see the assets folder in my project, i placed my xml file there and it works now :)

Android - iterating through Zipentry

I have large amount of files in a ZIP file (lets say 1000 images, some db files, binary files, ...). Inside it, I have some xml file I need to find and parse it. Information from it is shown to the screen. Problem is, when I am iterating through zip entry using:
InputStream inputStream = new FileInputStream(zipPath);
in = new ZipInputStream(inputStream);
for (ZipEntry entry = in.getNextEntry(); entry != null; entry = in.getNextEntry()) {
...some code here...
}
So when I am using Log.d, I see, it is iterating file by file, in case of large amount of files, it could take several minutes. Is there any better way, how to locate one specific file among others in ZIP file? "Brute force" approach I am using now is time consuming.
Thanks for any ideas
Waypoint

You can probably do this:
BufferedReader in = new BufferedReader(new InputStreamReader(zipfile.getInputStream(entry)));

When extracting specific files, you should be using a ZipFile. In particular, ZipFile.getEntry().
This should be no problem since you are using a File. However, if you only have an InputStream (or you prefer to use ZipInputStream for some reason) then, if you control how the zip file is built, you should put the XML file as the first entry.

Where to place an XML file containing data within an Android app

I am new to Android development. I have an XML file with data that the app will read. Where should I keep this XML file? Should it be stored within the "value" folder?

I'd say that depends. What do you save in your XML-File? There also is a res/xml-folder, where XML-Files can be kept. But Android does nearly anything with XML-Files, so you might want to read my little Tutorial about where to put which recourses.
Also, there is a difference between the assets and the res-directory's:
res
No subdirectorys are allowed under
the specific resource-folders.
The R-class indexes all resources
and provides simple access.
There are some simple methods which
help reading files stored in the
res-directory
assets
Subdirectorys are allowed (as much as
you like).
No indexing by the R-class
Reading resources stored in assets
is done using the AssetManager.

You can put it in the res/raw folder. Then you will access it using:
getResources().openRawResource(resourceName)

I had a similar requirement and after lot of research , I found 2 solution to place a custom XML :
You can place custom XML in
res/raw/
res/xml/
To access these location you will use following code :
a. if XML is placed in res/raw then :
getResources().openRawResource(R.raw.custom-xml) :
This gives you easy methods for reading xml :
with below code I am reading XML in memory placed in raw folder :
BufferedReader br = new BufferedReader(new InputStreamReader(getResources().openRawResource(R.raw.custom-xml)));
StringBuilder str = new StringBuilder();
String line;
while ( (line = br.readLine()) != null){
str.append(line);
}
2nd Option :
getResources().getxml(R.xml.custom-xml);
with this you could read the xml using eventbased parser.

Keep Strings into .txt file or put them into a Database?

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.