I have done many tests on an android emulator running in version 4.4. On my app I create a sqlite database with one table using SQLiteOpenHelper:
package com.findwords.modeles;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
import com.findwords.MainActivity;
import com.findwords.controleurs.MenuController;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
/**
* Created by louk on 02/01/14.
*/
public class DictionaryDbHelper extends SQLiteOpenHelper{
// declare constants fields
private static final String DB_PATH = "/data/data/com.findwords/databases/";
private static final String DB_NAME = "dictionary_db";
private static final int DB_VERSION = 1;
// declared constant SQL Expression
private static final String DB_CREATE =
"CREATE TABLE dictionary ( " +
"_id integer PRIMARY KEY AUTOINCREMENT, " +
"word text NOT NULL, " +
"definition text NOT NULL, " +
"length integer NOT NULL " +
");";
private static final String DB_DESTROY =
"DROP TABLE IF EXISTS dictionnary";
/*
* constructor
*/
public DictionaryDbHelper(Context context) {
super(context, DB_NAME, null, DB_VERSION);
}
/**
* 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 = MenuController.getInstance().getMainActivity().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();
}
/*
* (non-Javadoc)
* @see android.database.sqlite.SQLiteOpenHelper#onCreate(android.database.sqlite.SQLiteDatabase)
*/
@Override
public void onCreate(SQLiteDatabase db) {
db.execSQL(DB_CREATE);
try {
createDataBase();
} catch (IOException e) {
e.printStackTrace();
}
}
/*
* (non-Javadoc)
* @see android.database.sqlite.SQLiteOpenHelper#onUpgrade(android.database.sqlite.SQLiteDatabase, int, int)
*/
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL(DB_DESTROY);
onCreate(db);
}
}
Moreover I have written an adapter with a method open:
/*
* open database connection
*/
public DictionaryDbAdapter open() throws SQLException {
mDbHelper = new DictionaryDbHelper(mContext);
mDb = mDbHelper.getWritableDatabase();
return this;
}
It's working well on the emulator so the onCreate() method of the SQLiteOpenHelper class is called and create the database, but is not called on my phone (Google Nexus 5).
My phone is not rooted so I can't access the folder /data/data/com.myapp/databases .
However I want this application to work on any phone so I don't want to root my phone.
Thanks in advance to anyone who could help me.
