I’m developing a simple Android application with SQL. I followed the following guides – Using your own SQLite database in Android applications.
I get an error when trying to do a query the database.
Here is my DataBaseHelp.Java Class :
package namae.nombebe;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import android.content.Context;
import android.database.SQLException;
import android.database.sqlite.SQLiteDatabase;
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/namae.nombebe/databases/";
private static String DB_NAME = "myDBName";
private 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 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 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 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.
}
What i trying to do :
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
DataBaseHelper myDbHelper = new DataBaseHelper(null);
myDbHelper = new DataBaseHelper(this);
try
{
myDbHelper.createDataBase();
}
catch (IOException ioe)
{
throw new Error("Unable to create database");
}
try
{
myDbHelper.openDataBase();
}
catch(SQLException sqle)
{
throw sqle;
}
myDataBase = myDbHelper.getWritableDatabase();
Cursor c = myDataBase.rawQuery("SELECT * FROM A", null);
// problem on this query
}
So i don’t have any idea what going wrong.
I try with a simply database name “test.sqlite3”, there are two table “android_metadata” and “A”.
I have done
INSERT INTO “android_metadata” VALUES (‘en_US’)
And in A there only 2 column _id and TEXT, there is only one value “hello!” and “10”.
The error i have is :
07-30 13:39:03.886: E/AndroidRuntime(307): java.lang.RuntimeException: Unable to start activity ComponentInfo{namae.nombebe/namae.nombebe.NomBebeActivity}: android.database.sqlite.SQLiteException: no such table: A: , while compiling: SELECT * FROM A
So if anyone have any idea thanks in advance.
I have looking for hours.
When you instantiate, your code creates an empty DB, and then you are checking it from your activity and it already exists and the copy code doesn’t run. Thus the message that your table doesn’t exist when you then try to query.
An example DBAdapter class:
Then you call it from your activity like this: