Develop Reference

Android studio conection with SQL table DB browser

Straight to point:
I am making a Quizz app in Android studio. I would like to get the question (and answers) that will fill the app from SQL table that i made in DB browser for SQLite.
My question is how do i connect those two (without rettyping all those question in android studio).
I have in somethin like a structure {ID, qusetion, answer} and I only point ID number i whant to fetch from the table and it fills my array in android studio.
I hope this make sense :)
Regards

You could put every question and answer in a file, line by line, things separated by a specific character.
ex:
What's the color of the sky?;Blue;Red;Yello;Black
Who is Harry potter?;A magician;A girl;A burrito;A car
And read the file, and insert everything them in the database on the first time you open the app.

Assuming you're able to export from DB Browser to a .sql file (including CREATE TABLE statements as you'll effectively be creating a new database from scratch), you can use this exported file to recreate your database in your app.
By overriding the SQLiteOpenHelper.onCreate() method, you could do something like this:
#Override
public void onCreate(SQLiteDatabase db) {
// Open the raw SQL file
InputStream inputStream = context.getResources().openRawResource(R.raw.mydb);
BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
// Read the file
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line);
}
reader.close();
// Pump the statements into the database
String queries = sb.toString()
for (String query : queries.split(";")) {
db.execSQL(query);
}
}
Replacing mydb with whatever the name of your sql file is in /res/raw

Special chars like Umlaute are not saved correctly in android sqlite database

I can't save special characters like umlaute (e.g. Ä,Ü,ö, etc.) using sqlite in Android. Typing "ä" results in "\u00E4".
I've already tried following code to save a string in database, but didn't help:
ContentValues values = new ContentValues();
String content = comment.getContent().toString();
byte[] chars = content.getBytes("UTF-8");
String utf8Content = new String(chars, "UTF-8");
values.put(DBHandler.CONTENT,utf8Content);

As I know values.put accepts those characters like "ä". For some reason It can be saved in SQLite after converting that into Unicode character like "\u00E4". Simply in such case Save it in SQLite as it is and convert "\u00E4" again into "ä" when retrieving that data. Here is the method that returns those characters converting from Unicode characters.
public String getCharacterFromUnicode (String unicodeChar){
String returnString = null
try {
byte[] utf8 = unicodeChar.getBytes("UTF-8");
returnString = new String(utf8, "UTF-8");
}catch (Exception ex){
}
return returnString;
}
Which returns your "\u00E4" to "ä".
UPDATE :
If you are not sure which parts is converted to Unicode then use Apache commons-lang library to escape those,
myString = org.apache.commons.lang.StringEscapeUtils.unescapeJava(myString);

Try this
SQLiteDatabase.execSQL("PRAGMA ENCODING=UTF-8;");
or equivalent encoding you required

Txt file to a 2nd array (bidimensional array)

I am trying to do a bilinear interpolation and for that I have to read txt file which contains a NxM dimension.
I need to read the value for a specyfic row and column, I think on two options:
Read directly that value from txt file knowing at which column and row attempt. Any idea if its possible?
And the other, read all the file and store on a 2nd array, then read needed value pointing to the exact column and row on 2nd array.
The file separate each value with a doble space. I assume that file have to be stored on assets no? I will thank fot any code or documentation (I do not find out)
Thanks in advance ;)

Your app will definitely run faster if you load the txt file into a 2D array before working with the values. Opening something from persistent storage takes a lot longer than looking it up in memory.
Depending on the size of the array you may run out of memory, that's when you will need to be a bit more clever about which parts of the file you read into memory to work with at each stage.
There are plenty of questions on StackOverflow about reading a 2D array from a text file in Java and it should be similar in Android.

Hi finally I read a bidimensional array as:
public double[][] readArray2D(Context c, String file,int rows,int cols) throws IOException {
double [][] data = new double[rows][cols];
int row = 0;
int col = 0;
BufferedReader bufRdr = null;
try {
bufRdr = new BufferedReader(new InputStreamReader(c.getAssets().open(file)));
} catch (IOException e) {
e.printStackTrace();
}
String line = null;
//read each line of text file
try {
while((line = bufRdr.readLine()) != null && row < data.length)
{
StringTokenizer st = new StringTokenizer(line," ");
while (st.hasMoreTokens())
{
//get next token and store it in the array
data[row][col] = Double.parseDouble(st.nextToken());
col++;
}
col = 0;
row++;
}
} catch (IOException e) {
e.printStackTrace();
}
return data;
}
Thanks for all ;)

How to insert an accent into a sqlite table in android?

I am creating a database in Android, all was going nice, but when I was testing the queries retrieving the correct data I've got an error.
E/AndroidRuntime(14126): java.lang.IndexOutOfBoundsException: Invalid index 0, size is 0
I know that means that there is no data matching the query, but the fact is that I inserted the data by query and it actually has a match. And the same query works with all the codes that doesn't have accents.
These are the queries for inserting the rows.
INSERT INTO "codigo" VALUES('A','PEATÓN');
INSERT INTO "codigo" VALUES('B','PEATÓN');
INSERT INTO "codigo" VALUES('C','PEATÓN');
So I did a query that gets the values of the field that I was replacing, like this:
String selectCode = "select distinct c.tipo from codigo c";
Cursor cursor = database.rawQuery(selectCodigo, new String[] {});
cursor.moveToFirst();
while (!cursor.isAfterLast()) {
String codigo= cursor.getString(0);
codigos.add(codigo);
System.out.println(codigo);
cursor.moveToNext();
}
cursor.close();
return codigos;
And the result was this:
10-14 16:40:32.140: I/System.out(13716): PEAT�N
I have the text file in the /raw folder and I edited from the Eclipse so I make sure it wasn't the table export I did, but I have the same results.
This is the code that reads the file:
public int insertFromFile(SQLiteDatabase db,Context context, int resourceId) throws IOException {
// Reseting Counter
int result = 0;
// Open the resource
InputStream insertsStream = context.getResources().openRawResource(resourceId);
BufferedReader insertReader = new BufferedReader(new InputStreamReader(insertsStream));
// Iterate through lines (assuming each insert has its own line and theres no other stuff)
while (insertReader.ready()) {
String insertStmt = insertReader.readLine();
db.execSQL(insertStmt);
result++;
}
insertReader.close();
// returning number of inserted rows
return result;
}
How could I get that accent working?
I am using a lot of them, so, replacing the word is not a way out.
Please help, is the only thing I need to finish this project.
UPDATE:
Had the same problems two more times later. The first I fixed it by working with a .sql file coded in cp1525 and opened it in Eclipse with the default editor and find/replaced the wrong characters.
The last time I've got this error I made it the right way, and found that if you are working with SQLiteManager it imports files encoded in UTF-8 but it export files in ANSI, so I opened the file with Notepad++, change the enconding of the .sql file from ANSI to UTF-8 and it works fine, all the characters were shown fine.

The InputStreamReader constructor documentation says:
Constructs a new InputStreamReader on the InputStream in. This constructor sets the character converter to the encoding specified in the "file.encoding" property and falls back to ISO 8859_1 (ISO-Latin-1) if the property doesn't exist.
If the file is encoded in UTF-8, you have to tell the reader this.

in your SQLQueryString just add before
PRAGMA encoding = "UTF-8";
example
"PRAGMA encoding = \"UTF-8\"; INSERT INTO MYTABLE (mytablefield) VALUES ('value'); "

Reading a textfile database and displaying the results

I have a database thats in the form of a text file, my job is to parse the txt file and display the data in a listview. I have no idea where to start.
Heres an example entry.
"|9251115|,|0|,|DETAILS|,||,||,|Heading Price Text Text |,||,||
Where each || represents a field. There are also html tags between heading price and the text (p,b)
My first idea would be to parse it similarly to an xml document, i.e have it create a new line where it starts with a "|", fill it with everything in between and end the line when it reaches the next "|". But I still have no concrete idea on how to do this.
EDIT:
Taking it one step at a time for now. Using stringtokenizer to read it line by line and remove "," for a start. Ran into a problem, the textview to display the results is displaying false for some reason instead of the scanned text. here's my code if anyone needs a good headscratcher.
Context myContext;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
TextView t = (TextView) findViewById(R.id.text);
st = new ArrayList<property>();
try
{
InputStream is;
is = myContext.getAssets().open("rooms.txt");
BufferedReader br = new BufferedReader(new InputStreamReader(is,"UTF-8"));
String read = br.readLine();
while( read != null)
{
StringTokenizer st = new StringTokenizer(read,",");
{
while(st.hasMoreTokens())
{
String a = st.nextToken();
String b = st.nextToken();
String c = st.nextToken();
String d = st.nextToken();
String e = st.nextToken();
String f = st.nextToken();
String g = st.nextToken();
String h = st.nextToken();
t.setText(a+" "+b+" "+c+" "+d+" "+e+" "+f+" "+g+" "+h);
}
}
}
}
catch(Exception e)
{
e.printStackTrace();
}

While you can definitely implement your own parser using pure Java code, you should consider using a SQLite database (1) to store your data, which will allow you to insert, delete, modify and query much more easily.
If you database comes in that format from an external source, I'd write a one-time parser that parses the data and inserts it into the SQLite database for future use.
Remember that the CPU on Android devices is slower than your average PC CPU, so if you are parsing large amounts of data in this format all the time, your app might become very slow. Hence my suggestion of converting it to a database.
Another option you have in this case is using XML like you said, because there are ready-to-use parsers out there. But the advice about performance remains: you should really avoid reparsing the data all the time and, instead, store it in a ready-to-use format.
(1): http://developer.android.com/reference/android/database/sqlite/package-summary.html

Here is how I would do,
Have an object with getter/setter
Have a list intialized
1) You need to use StreamReaders/Bufferedreader to read the file
2) If each is not empty
2a) Use StringTokenizer to parse the string with "," as delimiter
2b) Set tokenized values to object
2c) Add object to list
3) return the list created in above step.
Note: If large data you need to be careful while reading entire file, you may get OutofMemoryError.

Bruno Oliveira gave very good advice.
You can parse your file by reading it line by line and then use string.split method, as result you will have all your data in an array where you can easily read and put into a list view or move it to a sqlite database.