Develop Reference

Replacing database with another database at runtime.

I have two databases, one database is the primary. This primary DB is responsible for holding the current data which is up to date and my secondary DB is populated via a cron job, once the primary DB gets obsolete I want to replace it with the secondary DB via a file operation of just over writing the existing DB and refreshing my views. Is it possible to do this, is there a better way?
So far what I have done is:
public void writeToSD() throws IOException {
File f=new File("/mnt/sdcard/dump.db");
FileInputStream fis=null;
FileOutputStream fos=null;
try{
fis=new FileInputStream(f);
fos=new FileOutputStream("/data/data/com.one.two/databases/Bdr");
while(true){
int i=fis.read();
if(i!=-1){
fos.write(i);
}
else{
break;
}
}
fos.flush();
}
catch(Exception e){
e.printStackTrace();
}
finally{
try{
fos.close();
fis.close();
}
catch(IOException ioe){
System.out.println(ioe);
}
}

How about always using the same database files (let's say dbA, dbB) with two instances of SQLiteOpenHelper and using an utility class like this instead of using raw SQLiteOpenHelper:
class Db {
private SQLiteOpenHelper mPrimaryDb;
private SQLiteOpenHelper mSecondaryDb;
public Db(Context context) {
mPrimaryDb = new MyDbHelper(context, "db_a");
mSecondaryDb = new MyDbHelper(context, "db_b");
}
public SQLiteOpenHelper getPrimaryDb() {
return mPrimaryDb;
}
public SQLiteOpenHelper getSecondaryDb() {
return mSecondaryDb;
}
public void swapDb() {
SQLiteOpenHelper tmp = mPrimaryDb;
mPrimaryDb = mSecondaryDb;
mSecondaryDb = tmp;
// TODO: notify data users that data has changed, cleanup the old primary database, etc.
}
{

If you want to use file operations, renaming the data base files is faster. But during file operations all connections have to be closed before any action.
If insertion is too slow, I would not overwrite the database file. I would generate the new database with a temp name and the same table and view structure. After finishing writing to the temp file I would rename the file to the same name as the invariant part of the old database plus a version number or a timestamp . And in my application I would look periodically for a new version, if found I would close all connections to the old file and open the new database.

Android SQLite Transaction, two datasources

im having doubts on how to procede with database manipulation using Begin Transaction
I have 2 data source objects: ClientDataSource and MovementsDataSource
each of theres has its own SQLitedabase object which is set with the Open() method with sets its database private Object with a Writable Database.
Now, i have to send the Records from the Movements Table to a server and then ask for the updated Clients from the same server.
Inside my class i first Send the new Movements, then if sucessful, delete all clients from the SQLite, and finally retrieve the new Updated Clients from the server and insert them into the database.
each data source has a Get() method for obtainting their respective Database Object, BUT it is in fact the same database they are operating and I am not sure of how to use the BaginTransction, Endtransaction methods to ensure data consistency
this is the code from the Async Task
#Override
protected Boolean doInBackground(String... url) {
try {
clientDataSource.open();
movementDataSource.open();
} catch (SQLException e) {
//Treat SQL Exception
}
try {
if(sendMovements()) {
clientDataSource.deleteAllClients();
}
updateDatabase(url[0]);
} catch (JSONException e) {
//Treat Json Exception
} catch (IOException e) {
//Treat IOException
}
return true;
}

i have to give one example then how begintransaction works...
public static void Insert(ArrayList<Model_CategoryMaster> categoryMasters) {
SQLiteDatabase sqldb = EGLifeStyleApplication.sqLiteDatabase;
sqldb.beginTransaction();
for (Model_CategoryMaster model : categoryMasters) {
ContentValues values = new ContentValues();
values.put(CATEGORY_ID, model.Category_Id);
values.put(CATEGORYNAME, model.CategoryName);
values.put(DESCRIPTION, model.Description);
values.put(ISACTIVE, model.IsActive);
values.put(CREATEDON, model.CreatedOn);
values.put(CREATEDBY, model.CreatedBy);
values.put(UPDATEDON, model.UpdatedOn);
values.put(UPDATEDBY, model.UpdatedBy);
values.put(ISDELETED, model.IsDeleted);
values.put(DELETEDON, model.DeletedOn);
values.put(DELETEDBY, model.DeletedBy);
values.put(PK_CATEGORYMASTER, model.PK_CategoryMaster);
if (!CommonMethod.CheckIsDataAlreadyInDBorNot(Table_Name,
CATEGORY_ID, model.Category_Id)) {
sqldb.insert(Table_Name, null, values);
} else {
sqldb.update(Table_Name, values, "Category_Id=?",
new String[] { model.Category_Id });
}
}
sqldb.setTransactionSuccessful();
sqldb.endTransaction();
}// End insert method
begin transaction means data will get arraylist then db will open one time and sql.begintansaction() use to get faster database operation.because db is not open or close more times.

How can i insert data in an sqlite table from a text file in android

In my application I am creating many tables in the sqlite database but in that one table contains more than 100k rows I get data from server using http connection. Getting this kind of many records causing much more time for me so to avoid this problem I want to connect my tablet through PC and I want to place txt file(which has insert statements) in the tablet.
Now how can I access that txt file in my application and how can I insert data in my table using that txt file and into which location I have to copy this txt file to access it from my application.
My DB file size also 273 MB, so I don't think it's possible to place it in the assets folder

you can copy the file to assets folder
code example:
private void initDatabaseData(SQLiteDatabase db) {
BufferedReader br = null;
try {
br = new BufferedReader(new InputStreamReader(context.getAssets().open(file_name)), 1024 * 4);
String line = null;
db.beginTransaction();
while ((line = br.readLine()) != null) {
db.execSQL(line);
}
db.setTransactionSuccessful();
} catch (IOException e) {
Log.e(LOG_TAG, "read database init file error");
} finally {
db.endTransaction();
if (br != null) {
try {
br.close();
} catch (IOException e) {
Log.e(LOG_TAG, "buffer reader close error");
}
}
}
}
above code require the every line of the txt file is a sql sentence

Performance SQLite Issue - Can a codechange speed up things?

I use the following code to add rows to my database :
public void insert(String kern, String woord) {
SQLiteDatabase db = getWritableDatabase();
ContentValues values = new ContentValues();
values.put(KERN, kern);
values.put(WOORD, woord);
db.insertOrThrow(TABLE_NAME, null, values);
return;
Currently, I'm invoking this insert() 3.455 times, to add all words to the database, using : insert("Fruits", "Banana"); It takes forever.
How can I change this code to work faster? I'm thinking in the line of foreach, but don't know how to implement.. Thanks!
/Edit; The solution provided by #hovanessyan works and will do the job. AND.. note that if you have a lot of lines that have to be put in, you might be confronted with the method exceeds max byte limit error. In that case, review the other solution, that suggests packing the database in the actual .APK file.

You can wrap-up those inserts into transaction.
db.beginTransaction();
try {
// do all the inserts here
//method call here, that does 1 insert; For example
addOneEntry(kern,woord);
...
db.setTransactionSuccessful();
} catch (SQLException e) {
//catch exceptions
} finally {
db.endTransaction();
}
private void addOneEntry(String kern, String woord) {
//prepare ContentValues
//do Insert
}

You can use bulkInsert:
ContentValues[] cvArr = new ContentValues[rows.size()];
int i = 0;
for (MyObject row : rows) {
ContentValues values = new ContentValues();
values.put(KERN, myObject.getKern());
values.put(WOORD, myObject.getWoord);
cvArr[i++] = values;
}// end for
resolver.bulkInsert(Tasks.CONTENT_URI, cvArr);

Using the tips of both hovanessyan and Damian (remind me to rep+1 you as soon as I reach 15 ;), I came up with the following solution:
For relatively small databases (<1,5Mb)
I created the database using SQLite Database Browser, and put it in my Assets folder.
Then, the following code copies the database to the device, if it's not already there:
boolean initialiseDatabase = (new File(DB_DESTINATION)).exists();
public void copyDB() throws IOException{
final String DB_DESTINATION = "/data/data/happyworx.nl.Flitswoorden/databases/WoordData.db";
// Check if the database exists before copying
Log.d("Database exist", "" + initialiseDatabase);
Log.d("Base Context", "" + getBaseContext());
if (initialiseDatabase == false) {
// Open the .db file in your assets directory
InputStream is = getBaseContext().getAssets().open("WoordData.db");
// Copy the database into the destination
OutputStream os = new FileOutputStream(DB_DESTINATION);
byte[] buffer = new byte[1024];
int length;
while ((length = is.read(buffer)) > 0){
os.write(buffer, 0, length);
}
os.flush();
os.close();
is.close();
}}
In my app, a portion of the database is User-customizable.
I call the code above in onStart() with :
try {
copyDB();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
So, when the user presses "reset database to standard" (in preferences screen), I just set the Boolean initialiseDatabase to "false" and wait for the user to go back to the main activity. (thus calling onstart and copying the original database).
I tried to call the Activity.copyDB() from the preferences.java. It's neater, because it doesn't require the user to go back to the main activity to rebuild the database. However, I get an error about not being able to call static references to non-static methods. I don't understand that, but will look into it.

How to parse the CSV file in android application?

I have a CSV file in drawable/asset folder. In the CSV file there are four columns. First one is for date and rest three are for integer data.
I need to parse this CSV file and save the data in separate arrays.
I have searched for a solution, but I don't get proper idea on how to do this.

I like this csv reader: https://mvnrepository.com/artifact/net.sf.opencsv/opencsv/2.3
Just add it to your project.
Example code (assuming there is the file assets/test.csv):
String next[] = {};
List<String[]> list = new ArrayList<String[]>();
try {
CSVReader reader = new CSVReader(new InputStreamReader(getAssets().open("test.csv")));
while(true) {
next = reader.readNext();
if(next != null) {
list.add(next);
} else {
break;
}
}
} catch (IOException e) {
e.printStackTrace();
}
You can access the imported data with, for example,
list.get(1)[1]
That would return a string.