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→11.2 Create Database File
===11.2 Create Database File===
We would like to create a database file including out Student Entity, so that we can put it in the project. Then every time the app runs, first it checks if it is the first time run of the app on the device or simulator. If so, the app will copy the file in to the SDCard. Next time that you run the application, it will know that the file is there, so will not override it. <Br/>
For this purpose, create a simple blackberry project with only the application object. We do not need any screen here. call it "DBCreator".
and this will need to only have a class called MyApp.java which extends UIApplication. Here is the code for this class:
<source lang="java" >
package mypackage;
import java.util.Enumeration;
import javax.microedition.io.file.FileSystemRegistry;
import net.rim.device.api.ui.*;
import net.rim.device.api.ui.component.*;
import net.rim.device.api.database.*;
import net.rim.device.api.io.*;
/**
* This class extends the UiApplication class, providing a
* graphical user interface.
*/
public class MyApp extends UiApplication
{
private static String DB_NAME = "SQLiteStudentList";
/**
* Entry point for application
* @param args Command line arguments (not used)
*/
public static void main(String[] args) throws Exception
{
// Create a new instance of the application and make the currently
// running thread the application's event dispatch thread.
MyApp theApp = new MyApp();
theApp.enterEventDispatcher();
}
/**
* Creates a new MyApp object
*/
public MyApp()throws Exception
{
// Push a screen onto the UI stack for rendering.
boolean sdCardPresent = false;
String root = null;
Enumeration e = FileSystemRegistry.listRoots();
while (e.hasMoreElements())
{
root = (String)e.nextElement();
if(root.equalsIgnoreCase("sdcard/"))
{
sdCardPresent = true;
}
}
if(!sdCardPresent)
{
UiApplication.getUiApplication().invokeLater(new Runnable()
{
public void run()
{
Dialog.alert("This application requires an SD card to be present. Exiting application...");
System.exit(0);
}
});
}
else
{
try{
// create a URI object with te file name and location
String dbLocation = "/SDCard/databases/DBCreator/";
URI uri = URI.create(dbLocation + DB_NAME);
// open a database connection to that URI
Database db = DatabaseFactory.openOrCreate(uri, new DatabaseSecurityOptions(false));
// create the table if it does not already exist
Statement statement = db.createStatement("CREATE TABLE IF NOT EXISTS Student(id INTEGER PRIMARY KEY, firstName TEXT, lastName TEXT, email TEXT, address TEXT)");
statement.prepare();
//execute the statement
statement.execute();
// close statement and database
statement.close();
db.close();
}catch(Exception ex ) {
errorDialog(ex.getMessage());
System.exit(0);
}
}
}
// Error message dialog
public static void errorDialog(final String message)
{
UiApplication.getUiApplication().invokeLater(new Runnable()
{
public void run()
{
Dialog.alert(message);
}
});
}
}
</source>
===11.3 Add id to Student Class===
