![]() In most cases this data is stored in an SQlite database.Ī content provider is implemented as a subclass of ContentProvider class and must implement a standard set of APIs that enable other applications to perform transactions. A content provider behaves very much like a database where you can query it, edit its content, as well as add or delete content using insert(), update(), delete(), and query() methods. This is where content providers become very useful.Ĭontent providers let you centralize content in one place and have many different applications access it as needed. ContentProvider sometimes it is required to share data across applications. A content provider can use different ways to store its data and the data can be stored in a database, in files, or even over a network. Such requests are handled by the methods of the ContentResolver class. This does allow for the database to have a column displayed, though the loadHandler prior allowed me to run a SQL query in the code, which was a step towards what the ambition of this project is looking to do. Thank you for your efforts and help with this. SQLiteDatabase.A content provider component supplies data from one application to others on request. The simplest way is to uninstall the App and then rerun the App. The code of this constructor looks like this: public MyDBHandler(Context context, Stringname, The database can be initialized in the constructor of the MyDBHandler class. We must also use import statements, as follows: import ![]() Type Student in the Name item, maintain the default options, and click the OK button:Īdding the following lines of code for the Student class: public class Student Right-click the myfirstdatabase package and selecting New > Java Class. The Student class contains fields, constructors, and properties as follows: My application model can be shown in the following figure: A third class (Student class) will need to be implemented to hold the database entry data as it is passed between the activity and the handler. The database handler will be a subclass of SQLiteOpenHelper and will provide an abstract layer between the underlying SQLite database and the activity class. The application will consist of an activity and a database handler class (MyDBHandler class). We will create a database Android application that has a UI as follows: getReadableDatabase(): creates or opens a database for reading only.ĬontentValues allows key/value pairs to be declared consisting of table column identifiers and the values to be stored in each column.getWritableDatabase(): opens or creates a database for reading and writing.onOpen(): called when the database is opened.onUpgrade(): called in the event that the application code contains a more recent database version number reference.onCreate(): called when the database is created for the first time.SQLiteOpenHelper is designed to make it easier to create and update databases. ![]() rawQuery(): executes an SQL query statement and returns matching results in the form of a Cursor object.execSQL(): executes a single SQL Statement that does not return result data.query(): performs a specified database query and returns matching results via a Cursor object.delete(): deletes rows from a database table.insert(): inserts a new row into a database table.SQLiteDatabase provides the primary interface between the application code and underlying SQLite database. get() (such as getInt(), getDouble(), so on): returns the value of the specified contained at the specified column index of the row at the current cursor position. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |