I know there are billions of threads about SQL Databases, but I didn’t find any solving my problem.
I’ve made an App called Beer Or No Beer which needs an Arraylist with beer brands and their country. Now I want to manage this list with SQLite. I’ve created a database with SQLite Database Browser and copied the database into the assets folder (name: sqbeerlist).
Now I’ve created a DatabaseHelper class to open the file and write it into an arraylist.
but when I want to acces the rows with
Cursor c = myDataBase.rawQuery("SELECT _id, brand FROM " + DATABASE_TABLE, null);
the DVM crashes and it says Source Not Found. WHAT AM I DOING WRONG ??
here is the whole HelperClass:
package com.celticwolf.alex;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
public class DataBaseHelper extends SQLiteOpenHelper {
// The Androids default system path of your application database.
private static String DB_PATH = "/data/data/com.celticwolf.alex/databases/";
private static String DB_NAME = "sqbeerlist";
private static final String DATABASE_TABLE = "beers";
private SQLiteDatabase myDataBase;
public static final String KEY_ROWID = "_id";
public static final String KEY_NAME = "brand";
public static final String KEY_COUNTRY = "country";
private final Context myContext;
public DataBaseHelper(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 doesnt
*/
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 doest 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 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();
}
public ArrayList<String> gettheArray() {
ArrayList<String> result = new ArrayList<String>();
try {
openDataBase();
}catch(SQLException sqle){
throw sqle;
}
Cursor c = myDataBase.rawQuery("SELECT _id, brand FROM " + DATABASE_TABLE, null);
c.moveToFirst();
// Check if our result was valid.
if (c != null) {
// Loop through all Results
do {
result.add(c.getString(c.getColumnIndex(KEY_NAME)));
} while (c.moveToNext());
}
close();
return result;
}
@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.
}
And here is how I access the class:
DataBaseHelper myDbHelper = new DataBaseHelper(null);
myDbHelper = new DataBaseHelper(this);
try {
myDbHelper.createDataBase();
} catch (IOException ioe) {
throw new Error("Unable to create database");
}
ArrayList<String> thelist = myDbHelper.gettheArray();
Thank you and I hope someone can help (:
Problem Solved!
Here is the correct Code!
This sign marks the changes: c==3
package com.celticwolf.alex;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import android.content.Context;
import android.database.Cursor;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteDatabase.CursorFactory;
import android.database.sqlite.SQLiteException;
import android.database.sqlite.SQLiteOpenHelper;
public class DataBaseHelper extends SQLiteOpenHelper {
// The Android's default system path of your application database.
private static String DB_PATH = "/data/data/com.celticwolf.alex/databases/";
private static String DB_NAME = "sqbeerlist.sqlite";
private static final String DATABASE_TABLE = "beers";
private SQLiteDatabase myDataBase;
public static final String KEY_ROWID = "_id";
public static final String KEY_NAME = "brand";
public static final String KEY_COUNTRY = "country";
private final Context myContext;
public DataBaseHelper(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();
SQLiteDatabase db_Read = null; // c==3
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.
db_Read = this.getReadableDatabase(); // c==3
db_Read.close(); // c==3
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 doesnt
*/
private boolean checkDataBase() {
SQLiteDatabase checkDB = null;
try {
String myPath = DB_PATH + DB_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null,
(SQLiteDatabase.OPEN_READONLY | SQLiteDatabase.NO_LOCALIZED_COLLATORS)); // c==3
} catch (SQLiteException e) {
// database doesnt 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 void openDataBase() throws SQLException {
// Open the database
String myPath = DB_PATH + DB_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, (SQLiteDatabase.OPEN_READONLY | SQLiteDatabase.NO_LOCALIZED_COLLATORS)); // c==3
}
@Override
public synchronized void close() {
if (myDataBase != null)
myDataBase.close();
super.close();
}
public ArrayList<String> gettheArray() {
ArrayList<String> result = new ArrayList<String>();
try {
openDataBase();
}catch(SQLException sqle){
throw sqle;
}
Cursor c = myDataBase.rawQuery("SELECT _id, brand FROM " + DATABASE_TABLE, null);
c.moveToFirst();
// Check if our result was valid.
if (c != null) {
// Loop through all Results
do {
result.add(c.getString(c.getColumnIndex(KEY_NAME)));
} while (c.moveToNext());
}
close();
return result;
}
@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 itd
// be easy
// to you to create adapters for your views.
}
I had this problem some time ago with copying the database across initially.
I ended up creating the database from scratch using resources (in assets or raw) in csv format on the first run of the app (obviously this may take up slightly more space)
Take a look at this thread and see if it helps.