visual basic print barcode label Figure 5.4 The WeatherReporter Saved Locations screen, which pulls data from a SQLite database in Java

Creator QR Code JIS X 0510 in Java Figure 5.4 The WeatherReporter Saved Locations screen, which pulls data from a SQLite database

Figure 5.4 The WeatherReporter Saved Locations screen, which pulls data from a SQLite database
Encode QR-Code In Java
Using Barcode maker for Android Control to generate, create QR Code JIS X 0510 image in Android applications.
www.OnBarcode.com
Paint Barcode In Java
Using Barcode drawer for Android Control to generate, create Barcode image in Android applications.
www.OnBarcode.com
Building and accessing a database
Printing Code 39 In Java
Using Barcode generation for Android Control to generate, create ANSI/AIM Code 39 image in Android applications.
www.OnBarcode.com
Generate PDF417 In Java
Using Barcode creation for Android Control to generate, create PDF-417 2d barcode image in Android applications.
www.OnBarcode.com
To use SQLite, you have to know a bit about SQL in general. If you need to brush up on the background of the basic commands, such as CREATE, INSERT, UPDATE, DELETE, and SELECT, then you might want to take a look at the SQLite documentation at http://www.sqlite.org/lang.html.
Draw EAN / UCC - 13 In Java
Using Barcode printer for Android Control to generate, create UCC - 12 image in Android applications.
www.OnBarcode.com
Drawing UPCA In Java
Using Barcode maker for Android Control to generate, create UPC-A Supplement 5 image in Android applications.
www.OnBarcode.com
Check out Charlie Collins site for Android SQLLite basics: http://www.screaming-penguin.com/node/ 7742.
EAN 13 Generator In Java
Using Barcode encoder for Android Control to generate, create EAN-13 image in Android applications.
www.OnBarcode.com
Painting Delivery Point Barcode (DPBC) In Java
Using Barcode creation for Android Control to generate, create Postnet image in Android applications.
www.OnBarcode.com
Persisting data to a database
Draw QR-Code In .NET
Using Barcode drawer for Reporting Service Control to generate, create QR Code image in Reporting Service applications.
www.OnBarcode.com
QR-Code Drawer In Objective-C
Using Barcode maker for iPad Control to generate, create QR Code image in iPad applications.
www.OnBarcode.com
For now, we ll jump right in and build a database helper class for our application. You need to create a helper class so that the details concerning creating and upgrading the database, opening and closing connections, and running through specific queries are all encapsulated in one place and not otherwise exposed or repeated in your application code. Your Activity and Service classes can use simple get and insert methods, with specific bean objects representing your model, rather than database-specific abstractions such as the Android Cursor object. You can think of this class as a miniature Data Access Layer (DAL). The following listing shows the first part of our DBHelper class, which includes a few useful inner classes.
GS1 - 13 Scanner In Java
Using Barcode decoder for Java Control to read, scan read, scan image in Java applications.
www.OnBarcode.com
Barcode Creator In Visual Studio .NET
Using Barcode printer for ASP.NET Control to generate, create Barcode image in ASP.NET applications.
www.OnBarcode.com
Listing 5.10 Portion of the DBHelper class showing the DBOpenHelper inner class
Making UCC.EAN - 128 In Java
Using Barcode generator for BIRT reports Control to generate, create UCC.EAN - 128 image in BIRT reports applications.
www.OnBarcode.com
Make UCC - 12 In None
Using Barcode encoder for Software Control to generate, create UPCA image in Software applications.
www.OnBarcode.com
public class DBHelper { public static final String DEVICE_ALERT_ENABLED_ZIP = "DAEZ99"; public static final String DB_NAME = "w_alert"; public static final String DB_TABLE = "w_alert_loc"; public static final int DB_VERSION = 3; private static final String CLASSNAME = DBHelper.class.getSimpleName(); private static final String[] COLS = new String[] { "_id", "zip", "city", "region", "lastalert", "alertenabled" }; private SQLiteDatabase db; Define constants private final DBOpenHelper dbOpenHelper; for database public static class Location { properties Define inner public long id; Location bean public long lastalert; public int alertenabled; public String zip; public String city; public String region;
Generating Data Matrix In None
Using Barcode generator for Software Control to generate, create DataMatrix image in Software applications.
www.OnBarcode.com
Paint Barcode In VB.NET
Using Barcode maker for VS .NET Control to generate, create Barcode image in VS .NET applications.
www.OnBarcode.com
. . . Location constructors and toString omitted for brevity } private static class DBOpenHelper extends SQLiteOpenHelper {
EAN13 Encoder In None
Using Barcode creator for Font Control to generate, create EAN-13 image in Font applications.
www.OnBarcode.com
Matrix 2D Barcode Generation In .NET Framework
Using Barcode generator for .NET framework Control to generate, create Matrix 2D Barcode image in .NET framework applications.
www.OnBarcode.com
Define inner DBOpenHelper class
ANSI/AIM Code 128 Recognizer In .NET
Using Barcode scanner for .NET Control to read, scan read, scan image in VS .NET applications.
www.OnBarcode.com
UPC Symbol Maker In Visual Basic .NET
Using Barcode creator for VS .NET Control to generate, create UPC-A Supplement 2 image in Visual Studio .NET applications.
www.OnBarcode.com
private static final String DB_CREATE = "CREATE TABLE " + DBHelper.DB_TABLE + " (_id INTEGER PRIMARY KEY, zip TEXT UNIQUE NOT NULL," + "city TEXT, region TEXT, lastalert INTEGER, " + "alertenabled INTEGER);"; public DBOpenHelper(Context context, String dbName, int version) { super(context, DBHelper.DB_NAME, null, DBHelper.DB_VERSION); } Define SQL query for
database creation @Override public void onCreate(SQLiteDatabase db) { try { Override db.execSQL(DBOpenHelper.DB_CREATE); helper callbacks } catch (SQLException e) { Log.e("ProviderWidgets", DBHelper.CLASSNAME, e); } }
Storing and retrieving data
@Override public void onOpen(SQLiteDatabase db) { super.onOpen(db); } @Override public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { db.execSQL("DROP TABLE IF EXISTS " + DBHelper.DB_TABLE); onCreate(db); } }
Within our DBHelper class, we first create constants that define important values for the database we want to work with, such as its name, version, and table B. Then we show several inner classes that we created to support the WeatherReporter application. The first inner class is a simple Location bean that represents a user s selected location C. This class intentionally doesn t provide accessors and mutators, because these add overhead and we don t expose the class externally. The second inner class is a SQLiteOpenHelper implementation D. Our DBOpenHelper inner class extends SQLiteOpenHelper, which Android provides to help with creating, upgrading, and opening databases. Within this class, we include a String that represents the CREATE query we ll use to build our database table; this shows the exact columns and types our table will have E. We also implement several key SQLiteOpenHelper callback methods F, notably onCreate and onUpgrade. We ll explain how these callbacks are invoked in the outer part of our DBHelper class, which is shown in the following listing.
Listing 5.11 Portion of the DBHelper class showing convenience methods
public DBHelper(Context context) { dbOpenHelper = new DBOpenHelper(context, "WR_DATA", 1); Create establishDb(); DBOpenHelper } instance private void establishDb() { if (db == null) { Open database db = dbOpenHelper.getWritableDatabase(); connection } } public void cleanup() { Tear down if (db != null) { database connection db.close(); db = null; } } public void insert(Location location) { Provide convenience ContentValues values = new ContentValues(); insert, update, values.put("zip", location.zip); delete, get values.put("city", location.city); values.put("region", location.region); values.put("lastalert", location.lastalert); values.put("alertenabled", location.alertenabled);
Copyright © OnBarcode.com . All rights reserved.