Ir al contenido principal

Android - Basic Steps (ContentProvider)

ContentProvider


Represents a repository of structured data
  • Is better than SQLite DB, because you can share data across multiple applications
  • Encapsulates data sets
  • The access is through ContentResolver
URI

ContentProviders referenced by URIs
    • Format: CONTENT://AUTHORITY/PATH/ID
      • Content - Schee indicating data that is managed by content provider
      • Authority - Id for the content provider
      • Path - 0 or more segments indicating the type of data to be accessed
      • Id - Specific record
    • Example
      • ContactsContract.Contacts.CONTENT_URI = "content://com.android.contects/contacts/"
      • Retrive in this case all the table because is missing the id

ContentResolver

  • Presents a DB-style interface for read and wite data
  • Provide service as Change notification
How to use
  • Get a reference to ContentResolver
    • Context.getContentResolver()
Types
  • Brower - Bookmarks, history
  • Call log - Telephone usage
  • Contacts
  • Media - Gallery image
  • UserDictionary - predictive spelling
Methods
  • ContentResolver.Query
    • Cursosr query(
      • Uri uri    - ContentProvider Uri
      • String[] projection    - Columns to retrieve
      • String selection     - SQL selection pattern
      • String[] selectionArgs   - SQL pattern args
      • String sortOrder  - Sort order
    • )
    • Returns a cursos for interating over the set of results
  • ContentResolver.delete(
    • Uri uri,    - ContentProvider Uri
    • String where,  - SQL selection pattern
    • String[] selectArgs  - SQL pattern args
    • )
    • Returns the number of rows deleted
  • ContentResolver.insert(
    • Uri uri,    - ContentProvider Uri
    • ContentValues
    • )
    • Returns the URI of the inserted row
  • ContentResolver.update(
    • Uri uri,    - ContentProvider Uri
    • ContentValues
    • String where,  - SQL selection pattern
    • String[] selectArgs  - SQL pattern args
    • )
    • Returns the number of rows updated

CursorLoader

Use AsyncTask to perform queries on a background thread

How to use
  • Implement LoaderManager's LoaderCallbacks interface
    • Create and Initialize a cursor loader with initLoader()
      • Loader<D> initLoader( int id, Bundle args, LoaderCallbacks<D> callback)
    • Then call  method onCreateLoader()
      • LoaderCallbacks
        • First callback instantiate and return a new loader for the specified id
    • Last call the method onLoadFinished
  •  To reset a loader use
    • onLoaderReset(...)


Comentarios

Publicar un comentario

Entradas populares de este blog

C# Using tabs

To use tabs in C# use the TabContainer element from AjaxControlToolkit Include AjaxControlToolkit  Include in the Web.config file, inside the tag <system.web> the following code  <pages>       <controls>         <add tagPrefix="ajaxCTK" namespace="AjaxControlToolkit" assembly="AjaxControlToolkit"/>       </controls>     </pages>   Include TabContainer element First  include TabContainer element that is the section where all the tabs will be displayed. <ajaxCTK:TabContainer ID="TabContainerUpdate" runat="server"                 Height="800"                 CssClass="ajax__tab_style"> </ajaxCTK:TabContainer> Second per each tab include the following code corresponding to each ...
Publicar un comentario
Leer más

Rails - Basic Steps III

pValidations Validations are a type of ActiveRecord Validations are defined in our models Implement Validations Go to   root_app/app/models Open files  *.rb for each model Mandatory field validates_presence_of   :field Ex:   validates_presence_of    :title Classes The basic syntax is class MyClass        @global_variable                def my_method              @method_variable        end end Create an instance myInstance = MyClass.new Invoke a mehod mc.my_method class() method returns the type of the object In Ruby, last character of method define the behavior If ends with a question -> return a boolean value If ends with an exclamation -> change the state of the object Getter / Setter method def global_variable       return @global_variable end ...
Publicar un comentario
Leer más

Python create package

Create a root folder Create a sub-folder "example_pkg" that contains the funtionallity packaging_tutorial/ example_pkg/ __init__.py In the root folder create the following structure  packaging_tutorial/ example_pkg/ __init__.py tests/ setup.py LICENSE README.md in the setup.py contains the configuration of the packages your package is found by find_packages() import setuptools with open ( "README.md" , "r" ) as fh : long_description = fh . read () setuptools . setup ( name = "example-pkg-YOUR-USERNAME-HERE" , # Replace with your own username version = "0.0.1" , author = "Example Author" , author_email = "author@example.com" , description = "A small example package" , long_description = long_description , long_description_content_type = "text/markdown" , url = "https://github.com/pypa/sam...
Publicar un comentario
Leer más