vendredi 13 février 2015

How to get values from my own database

I have a database .sqlite and I want to use it on my android app and get some data of it. I see this tutorial: http://ift.tt/19PBhQ1 But now I want to save some data in a String [] to after put it on a listview, but i don't know how to retrieve the data of the database. I have comidas.sqlite in \myproject\app\src\main\assets (I created the assets folder where I have the "java" and "res" folder but I don't know if is the correct folder) and I have the DBAlimentos.java class where I connect to the database (I use the code of the link of the top) but now I don't know how to retrieve data in my activity. The data that I want to save is all the records that returns this line: "SELECT nombre FROM comida WHERE imagen_id='1' ".


My DBAlimentos.java code:



public class DBAlimentos extends SQLiteOpenHelper {

//The Android's default system path of your application database.
private static String DB_PATH = "/data/data/es.bawi.testdeporte/databases/";

private static String DB_NAME = "comidas.sqlite";

public static SQLiteDatabase myDataBase;

private final Context myContext;

/**
* Constructor
* Takes and keeps a reference of the passed context in order to access to the application assets and resources.
* @param context
*/
public DBAlimentos(Context context) {

super(context, DB_NAME, null, 1);
this.myContext = context;
}

/**
* Creates a empty database on the system and rewrites it with your own database.
* */
public void createDataBase() throws IOException {

boolean dbExist = checkDataBase();

if(dbExist){
//do nothing - database already exist
}else{

//By calling this method and empty database will be created into the default system path
//of your application so we are gonna be able to overwrite that database with our database.
this.getReadableDatabase();

try {

copyDataBase();

} catch (IOException e) {

throw new Error("Error copying database");

}
}

}

/**
* Check if the database already exist to avoid re-copying the file each time you open the application.
* @return true if it exists, false if it doesn't
*/
private boolean checkDataBase(){

SQLiteDatabase checkDB = null;

try{
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

}catch(SQLiteException e){

//database does't exist yet.

}

if(checkDB != null){

checkDB.close();

}

return checkDB != null ? true : false;
}

/**
* Copies your database from your local assets-folder to the just created empty database in the
* system folder, from where it can be accessed and handled.
* This is done by transfering bytestream.
* */
private void copyDataBase() throws IOException{

//Open your local db as the input stream
InputStream myInput = myContext.getAssets().open(DB_NAME);

// Path to the just created empty db
String outFileName = DB_PATH + DB_NAME;

//Open the empty db as the output stream
OutputStream myOutput = new FileOutputStream(outFileName);

//transfer bytes from the inputfile to the outputfile
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer))>0){
myOutput.write(buffer, 0, length);
}

//Close the streams
myOutput.flush();
myOutput.close();
myInput.close();

}

public static void openDataBase() throws SQLException {

//Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READONLY);

}

@Override
public synchronized void close() {

if(myDataBase != null)
myDataBase.close();

super.close();

}

@Override
public void onCreate(SQLiteDatabase db) {

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}

// Add your public helper methods to access and get content from the database.
// You could return cursors by doing "return myDataBase.query(....)" so it'd be easy
// to you to create adapters for your views.

}


Thanks and sorry for my bad english..


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