Listing 99 srccomcookbookdataMyDBjava

package com.cookbook.data;

import android.content.ContentValues;

import android.content.Context;

import android.database.Cursor;

import android.database.sqlite.SQLiteDatabase;

import android.database.sqlite.SQLiteException;

import android.util.Log;

public class MyDB {

private SQLiteDatabase db; private final Context context; private final MyDBhelper dbhelper; public MyDB(Context c){ context = c;

dbhelper = new MyDBhelper(context, Constants.DATABASE_NAME, null,

Constants.DATABASE_VERSION);

public void close() {

public void open() throws SQLiteException {

db = dbhelper.getWritableDatabase(); } catch(SQLiteException ex) {

Log.v("Open database exception caught", ex.getMessage()); db = dbhelper.getReadableDatabase();

public long insertdiary(String title, String content) {

try{

ContentValues newTaskValue = new ContentValues(); newTaskValue.put(Constants.TITLE_NAME, title); newTaskValue.put(Constants.CONTENT_NAME, content); newTaskValue.put(Constants.DATE_NAME, java.lang.System.currentTimeMillis()); return db.insert(Constants.TABLE_NAME, null, newTaskValue); } catch(SQLiteException ex) {

Log.v("Insert into database exception caught", ex.getMessage()); return -1;

public Cursor getdiaries() {

Cursor c = db.query(Constants.TABLE_NAME, null, null, null, null, null, null);

return c;

The MyDBhelper class extends SQLiteOpenHelper and is shown in Listing 9.10.The SQLiteOpenHelper framework provides methods to manage database creation and upgrades. The database is initialized in the class constructor MyDBhelper() .This requires the context and database name to be specified for creation of the database file under /data/data/com.cookbook.datastorage/databases and database schema version to determine whether the onCreate() or onUpgrade() method is called.

Tables can be added in the onCreate() method using a custom SQL command such as:

create table MyTable (key_id integer primary key autoincrement, title text not null, content text not null, recorddate long);

Whenever a database needs to be upgraded (when a user downloads a new version of an application, for example), the change in database version number calls the onUpgrade() method. This can be used to alter or drop tables as needed to update the tables to the new schema.

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