|  | excludeFromSuggestions=true | 
|  | page.title=Notepad Exercise 1 | 
|  | parent.title=Notepad Tutorial | 
|  | parent.link=index.html | 
|  | @jd:body | 
|  |  | 
|  |  | 
|  | <p><em>In this exercise, you will construct a simple notes list that lets the | 
|  | user add new notes but not edit them. The exercise demonstrates:</em></p> | 
|  | <ul> | 
|  | <li><em>The basics of <code>ListActivities</code> and creating and handling menu | 
|  | options. </em></li> | 
|  | <li><em>How to use a SQLite database to store the notes.</em></li> | 
|  | <li><em>How to bind data from a database cursor into a ListView using a | 
|  | SimpleCursorAdapter.</em></li> | 
|  | <li><em>The basics of screen layouts, including how to lay out a list view, how | 
|  | you can add items to the activity menu, and how the activity handles those menu | 
|  | selections. </em></li> | 
|  | </ul> | 
|  |  | 
|  | <div style="float:right;white-space:nowrap"> | 
|  | <span style="color:#BBB;"> | 
|  | [<a href="notepad-ex1.html" style="color:#BBB;">Exercise 1</a>]</span> | 
|  | [<a href="notepad-ex2.html">Exercise 2</a>] | 
|  | [<a href="notepad-ex3.html">Exercise 3</a>] | 
|  | [<a href="notepad-extra-credit.html">Extra Credit</a>] | 
|  | </div> | 
|  |  | 
|  |  | 
|  |  | 
|  | <h2>Step 1</h2> | 
|  |  | 
|  | <p>Open up the <code>Notepadv1</code> project in Eclipse.</p> | 
|  |  | 
|  | <p><code>Notepadv1</code> is a project that is provided as a starting point. It | 
|  | takes care of some of the boilerplate work that you have already seen if you | 
|  | followed the <a href="{@docRoot}training/basics/firstapp/index.html">Hello, | 
|  | World</a> tutorial.</p> | 
|  |  | 
|  | <ol> | 
|  | <li> | 
|  | Start a new Android Project by clicking <strong>File</strong> > | 
|  | <strong>New</strong> > <strong>Android Project</strong>.</li> | 
|  | <li> | 
|  | In the New Android Project dialog, select <strong>Create project from existing source</strong>.</li> | 
|  | <li> | 
|  | Click <strong>Browse</strong> and navigate to where you copied the <code>NotepadCodeLab</code> | 
|  | (downloaded during <a href="{@docRoot}training/notepad/index.html#preparing">setup</a>) | 
|  | and select <code>Notepadv1</code>.</li> | 
|  | <li> | 
|  | The Project Name and other properties should be automatically filled for you. | 
|  | You must select the Build Target—we recommend selecting a target with the | 
|  | lowest platform version available. Also add an integer to the Min SDK Version field | 
|  | that matches the API Level of the selected Build Target.</li> | 
|  | <li> | 
|  | Click <strong>Finish</strong>. The <code>Notepadv1</code> project should open and be | 
|  | visible in your Eclipse package explorer.</li> | 
|  | </ol> | 
|  |  | 
|  | <p>If you see an error about <code>AndroidManifest.xml</code>, or some | 
|  | problems related to an Android zip file, right click on the project and | 
|  | select <strong>Android Tools</strong> > <strong>Fix Project Properties</strong>. | 
|  | (The project is looking in the wrong location for the library file, | 
|  | this will fix it for you.)</p> | 
|  |  | 
|  | <h2>Step 2</h2> | 
|  |  | 
|  | <div class="sidebox-wrapper"> | 
|  | <div class="sidebox"> | 
|  | <h2>Accessing and modifying data</h2> | 
|  | <p>For this | 
|  | exercise, we are using a SQLite database to store our data. This is useful | 
|  | if only <em>your</em> application will need to access or modify the data. If you wish for | 
|  | other activities to access or modify the data, you have to expose the data using a | 
|  | {@link android.content.ContentProvider ContentProvider}.</p> | 
|  | <p>If you are interested, you can find out more about | 
|  | <a href="{@docRoot}guide/topics/providers/content-providers.html">content providers</a> or the | 
|  | whole | 
|  | subject of <a href="{@docRoot}guide/topics/data/data-storage.html">Data Storage</a>. | 
|  | The NotePad sample in the <code>samples/</code> folder of the SDK also has an example of how | 
|  | to create a ContentProvider.</p> | 
|  | </div> | 
|  | </div> | 
|  |  | 
|  | <p>Take a look at the <code>NotesDbAdapter</code> class — this class is provided to | 
|  | encapsulate data access to a SQLite database that will hold our notes data | 
|  | and allow us to update it.</p> | 
|  | <p>At the top of the class are some constant definitions that will be used in the application | 
|  | to look up data from the proper field names in the database. There is also a database creation | 
|  | string defined, which is used to create a new database schema if one doesn't exist already.</p> | 
|  | <p>Our database will have the name <code>data</code>, and have a single table called | 
|  | <code>notes</code>, which in turn has three fields: <code>_id</code>, <code>title</code> and | 
|  | <code>body</code>. The <code>_id</code> is named with an underscore convention used in a number of | 
|  | places inside the Android SDK and helps keep a track of state. The <code>_id</code> | 
|  | usually has to be specified when querying or updating the database (in the column projections | 
|  | and so on). The other two fields are simple text fields that will store data. | 
|  | </p> | 
|  | <p>The constructor for <code>NotesDbAdapter</code> takes a Context, which allows it to communicate with aspects | 
|  | of the Android operating system. This is quite common for classes that need to touch the | 
|  | Android system in some way. The Activity class implements the Context class, so usually you will just pass | 
|  | <code>this</code> from your Activity, when needing a Context.</p> | 
|  | <p>The <code>open()</code> method calls up an instance of DatabaseHelper, which is our local | 
|  | implementation of the SQLiteOpenHelper class. It calls <code>getWritableDatabase()</code>, | 
|  | which handles creating/opening a database for us.</p> | 
|  | <p><code>close()</code> just closes the database, releasing resources related to the | 
|  | connection.</p> | 
|  | <p><code>createNote()</code> takes strings for the title and body of a new note, | 
|  | then creates that note in the database. Assuming the new note is created successfully, the | 
|  | method also returns the row <code>_id</code> value for the newly created note.</p> | 
|  | <p><code>deleteNote()</code> takes a <var>rowId</var> for a particular note, and deletes that note from | 
|  | the database.</p> | 
|  |  | 
|  | <p><code>fetchAllNotes()</code> issues a query to return a {@link android.database.Cursor} over all notes in the | 
|  | database. The <code>query()</code> call is worth examination and understanding. The first field is the | 
|  | name of the database table to query (in this case <code>DATABASE_TABLE</code> is "notes"). | 
|  | The next is the list of columns we want returned, in this case we want the <code>_id</code>, | 
|  | <code>title</code> and <code>body</code> columns so these are specified in the String array. | 
|  | The remaining fields are, in order: <code>selection</code>, | 
|  | <code>selectionArgs</code>, <code>groupBy</code>, <code>having</code> and <code>orderBy</code>. | 
|  | Having these all <code>null</code> means we want all data, need no grouping, and will take the default | 
|  | order. See {@link android.database.sqlite.SQLiteDatabase SQLiteDatabase} for more details.</p> | 
|  | <p class="note"><b>Note:</b> A Cursor is returned rather than a collection of rows. This allows | 
|  | Android to use resources efficiently -- instead of putting lots of data straight into memory | 
|  | the cursor will retrieve and release data as it is needed, which is much more efficient for | 
|  | tables with lots of rows.</p> | 
|  |  | 
|  | <p><code>fetchNote()</code> is similar to <code>fetchAllNotes()</code> but just gets one note | 
|  | with the <var>rowId</var> we specify. It uses a slightly different version of the | 
|  | {@link android.database.sqlite.SQLiteDatabase} <code>query()</code> method. | 
|  | The first parameter (set <em>true</em>) indicates that we are interested | 
|  | in one distinct result. The <var>selection</var> parameter (the fourth parameter) has been specified to search | 
|  | only for the row "where _id =" the <var>rowId</var> we passed in. So we are returned a Cursor on | 
|  | the one row.</p> | 
|  | <p>And finally, <code>updateNote()</code> takes a <var>rowId</var>, <var>title</var> and <var>body</var>, and uses a | 
|  | {@link android.content.ContentValues ContentValues} instance to update the note of the given | 
|  | <var>rowId</var>.</p> | 
|  |  | 
|  | <h2 style="clear:right;">Step 3</h2> | 
|  |  | 
|  | <div class="sidebox-wrapper"> | 
|  | <div class="sidebox"> | 
|  | <h2>Layouts and activities</h2> | 
|  | <p>Most Activity classes will have a layout associated with them. The layout | 
|  | will be the "face" of the Activity to the user. In this case our layout will | 
|  | take over the whole screen and provide a list of notes.</p> | 
|  | <p>Full screen layouts are not the only option for an Activity however. You | 
|  | might also want to use a <a | 
|  | href="{@docRoot}resources/faq/commontasks.html#floatingorfull">floating | 
|  | layout</a> (for example, a <a | 
|  | href="{@docRoot}resources/faq/commontasks.html#dialogsandalerts">dialog | 
|  | or alert</a>), | 
|  | or perhaps you don't need a layout at all (the Activity will be invisible | 
|  | to the user unless you specify some kind of layout for it to use).</p> | 
|  | </div> | 
|  | </div> | 
|  |  | 
|  | <p>Open the <code>notepad_list.xml</code> file in <code>res/layout</code> | 
|  | and | 
|  | take a look at it. (You may have to | 
|  | hit the <em>xml</em> tab, at the bottom, in order to view the XML markup.)</p> | 
|  |  | 
|  | <p>This is a mostly-empty layout definition file. Here are some | 
|  | things you should know about a layout file:</p> | 
|  |  | 
|  |  | 
|  | <ul> | 
|  | <li> | 
|  | All Android layout files must start with the XML header line: | 
|  | <code><?xml version="1.0" encoding="utf-8"?></code>.    </li> | 
|  | <li> | 
|  | The next definition will often (but not always) be a layout | 
|  | definition of some kind, in this case a <code>LinearLayout</code>.    </li> | 
|  | <li> | 
|  | The XML namespace of Android should always be defined in | 
|  | the top level component or layout in the XML so that <code>android:</code> tags can | 
|  | be used through the rest of the file: | 
|  | <p><code>xmlns:android="http://schemas.android.com/apk/res/android"</code></p> | 
|  | </li> | 
|  | </ul> | 
|  |  | 
|  | <h2 style="clear:right;">Step 4</h2> | 
|  | <p>We need to create the layout to hold our list. Add code inside | 
|  | of the <code>LinearLayout</code> element so the whole file looks like this: </p> | 
|  | <pre> | 
|  | <?xml version="1.0" encoding="utf-8"?> | 
|  | <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" | 
|  | android:layout_width="wrap_content" | 
|  | android:layout_height="wrap_content"> | 
|  |  | 
|  | <ListView android:id="@android:id/list" | 
|  | android:layout_width="wrap_content" | 
|  | android:layout_height="wrap_content"/> | 
|  | <TextView android:id="@android:id/empty" | 
|  | android:layout_width="wrap_content" | 
|  | android:layout_height="wrap_content" | 
|  | android:text="@string/no_notes"/> | 
|  |  | 
|  | </LinearLayout> | 
|  | </pre> | 
|  | <ul> | 
|  | <li> | 
|  | The <strong>@</strong> symbol in the id strings of the <code>ListView</code> and | 
|  | <code>TextView</code> tags means | 
|  | that the XML parser should parse and expand the rest of | 
|  | the id string and use an ID resource.</li> | 
|  | <li> | 
|  | The <code>ListView</code> and <code>TextView</code> can be | 
|  | thought as two alternative views, only one of which will be displayed at once. | 
|  | ListView will be used when there are notes to be shown, while the TextView | 
|  | (which has a default value of "No Notes Yet!" defined as a string | 
|  | resource in <code>res/values/strings.xml</code>) will be displayed if there | 
|  | aren't any notes to display.</li> | 
|  | <li>The <code>list</code> and <code>empty</code> IDs are | 
|  | provided for us by the Android platform, so, we must | 
|  | prefix the <code>id</code> with <code>android:</code> (e.g., <code>@android:id/list</code>).</li> | 
|  | <li>The View with the <code>empty</code> id is used | 
|  | automatically when the {@link android.widget.ListAdapter} has no data for the ListView. The | 
|  | ListAdapter knows to look for this name by default. Alternatively, you could change the | 
|  | default empty view by using {@link android.widget.AdapterView#setEmptyView(View)} | 
|  | on the ListView. | 
|  | <p> | 
|  | More broadly, the <code>android.R</code> class is a set of predefined | 
|  | resources provided for you by the platform, while your project's | 
|  | <code>R</code> class is the set of resources your project has defined. | 
|  | Resources found in the <code>android.R</code> resource class can be | 
|  | used in the XML files by using the <code>android:</code> name space prefix | 
|  | (as we see here).</p> | 
|  | </li> | 
|  | </ul> | 
|  |  | 
|  | <h2 style="clear:right;">Step 5</h2> | 
|  |  | 
|  | <div class="sidebox-wrapper"> | 
|  | <div class="sidebox"> | 
|  | <h2>Resources and the R class</h2> | 
|  | <p>The folders under res/ in the Eclipse project are for resources. | 
|  | There is a <a href="{@docRoot}resources/faq/commontasks.html#filelist">specific structure</a> | 
|  | to the | 
|  | folders and files under res/.</p> | 
|  | <p>Resources defined in these folders and files will have | 
|  | corresponding entries in the R class allowing them to be easily accessed | 
|  | and used from your application. The R class is automatically generated using the contents | 
|  | of the res/ folder by the eclipse plugin (or by aapt if you use the command line tools). | 
|  | Furthermore, they will be bundled and deployed for you as part of the application.</p> | 
|  | </p> | 
|  | </div> | 
|  | </div> | 
|  |  | 
|  | <p>To make the list of notes in the ListView, we also need to define a View for each row:</p> | 
|  | <ol> | 
|  | <li> | 
|  | Create a new file under <code>res/layout</code> called | 
|  | <code>notes_row.xml</code>.    </li> | 
|  | <li> | 
|  | Add the following contents (note: again the XML header is used, and the | 
|  | first node defines the Android XML namespace)<br> | 
|  | <pre style="overflow:auto"> | 
|  | <?xml version="1.0" encoding="utf-8"?> | 
|  | <TextView android:id="@+id/text1" | 
|  | xmlns:android="http://schemas.android.com/apk/res/android" | 
|  | android:layout_width="wrap_content" | 
|  | android:layout_height="wrap_content"/></pre> | 
|  | <p> | 
|  | This is the View that will be used for each notes title row — it has only | 
|  | one text field in it.    </p> | 
|  | <p>In this case we create a new id called <code>text1</code>. The | 
|  | <strong>+</strong> after the <strong>@</strong> in the id string indicates that the id should | 
|  | be automatically created as a resource if it does not already exist, so we are defining | 
|  | <code>text1</code> on the fly and then using it.</p> | 
|  | </li> | 
|  | <li>Save the file.</li> | 
|  | </ol> | 
|  | <p>Open the <code>R.java</code> class in the | 
|  | project and look at it, you should see new definitions for | 
|  | <code>notes_row</code> and <code>text1</code> (our new definitions) | 
|  | meaning we can now gain access to these from the our code. </p> | 
|  |  | 
|  | <h2 style="clear:right;">Step 6</h2> | 
|  | <p>Next, open the <code>Notepadv1</code> class in the source. In the following steps, we are going to | 
|  | alter this class to become a list adapter and display our notes, and also | 
|  | allow us to add new notes.</p> | 
|  |  | 
|  | <p><code>Notepadv1</code> will inherit from a subclass | 
|  | of <code>Activity</code> called a <code>ListActivity</code>, | 
|  | which has extra functionality to accommodate the kinds of | 
|  | things you might want to do with a list, for | 
|  | example: displaying an arbitrary number of list items in rows on the screen, | 
|  | moving through the list items, and allowing them to be selected.</p> | 
|  |  | 
|  | <p>Take a look through the existing code in <code>Notepadv1</code> class. | 
|  | There is a currently an unused private field called <code>mNoteNumber</code> that | 
|  | we will use to create numbered note titles.</p> | 
|  | <p>There are also three override methods defined: | 
|  | <code>onCreate</code>, <code>onCreateOptionsMenu</code> and | 
|  | <code>onOptionsItemSelected</code>; we need to fill these | 
|  | out:</p> | 
|  | <ul> | 
|  | <li><code>onCreate()</code> is called when the activity is | 
|  | started — it is a little like the "main" method for an Activity. We use | 
|  | this to set up resources and state for the activity when it is | 
|  | running.</li> | 
|  | <li><code>onCreateOptionsMenu()</code> is used to populate the | 
|  | menu for the Activity. This is shown when the user hits the menu button, | 
|  | and | 
|  | has a list of options they can select (like "Create | 
|  | Note"). </li> | 
|  | <li><code>onOptionsItemSelected()</code> is the other half of the | 
|  | menu equation, it is used to handle events generated from the menu (e.g., | 
|  | when the user selects the "Create Note" item). | 
|  | </li> | 
|  | </ul> | 
|  |  | 
|  | <h2>Step 7</h2> | 
|  | <p>Change the inheritance of <code>Notepadv1</code> from | 
|  | <code>Activity</code> | 
|  | to <code>ListActivity</code>:</p> | 
|  | <pre>public class Notepadv1 extends ListActivity</pre> | 
|  | <p>Note: you will have to import <code>ListActivity</code> into the | 
|  | Notepadv1 | 
|  | class using Eclipse, <strong>ctrl-shift-O</strong> on Windows or Linux, or | 
|  | <strong>cmd-shift-O</strong> on the Mac (organize imports) will do this for you | 
|  | after you've written the above change.</p> | 
|  |  | 
|  | <h2>Step 8</h2> | 
|  | <p>Fill out the body of the <code>onCreate()</code> method.</p> | 
|  | <p>Here we will set the title for the Activity (shown at the top of the | 
|  | screen), use the <code>notepad_list</code> layout we created in XML, | 
|  | set up the <code>NotesDbAdapter</code> instance that will | 
|  | access notes data, and populate the list with the available note | 
|  | titles:</p> | 
|  | <ol> | 
|  | <li> | 
|  | In the <code>onCreate</code> method, call <code>super.onCreate()</code> with the | 
|  | <code>savedInstanceState</code> parameter that's passed in.</li> | 
|  | <li> | 
|  | Call <code>setContentView()</code> and pass <code>R.layout.notepad_list</code>.</li> | 
|  | <li> | 
|  | At the top of the class, create a new private class field called <code>mDbHelper</code> of class | 
|  | <code>NotesDbAdapter</code>. | 
|  | </li> | 
|  | <li> | 
|  | Back in the <code>onCreate</code> method, construct a new | 
|  | <code>NotesDbAdapter</code> | 
|  | instance and assign it to the <code>mDbHelper</code> field (pass | 
|  | <code>this</code> into the constructor for <code>DBHelper</code>) | 
|  | </li> | 
|  | <li> | 
|  | Call the <code>open()</code> method on <code>mDbHelper</code> to open (or create) the | 
|  | database. | 
|  | </li> | 
|  | <li> | 
|  | Finally, call a new method <code>fillData()</code>, which will get the data and | 
|  | populate the ListView using the helper — we haven't defined this method yet.    </li> | 
|  | </ol> | 
|  | <p> | 
|  | <code>onCreate()</code> should now look like this:</p> | 
|  | <pre> | 
|  | @Override | 
|  | public void onCreate(Bundle savedInstanceState) { | 
|  | super.onCreate(savedInstanceState); | 
|  | setContentView(R.layout.notepad_list); | 
|  | mDbHelper = new NotesDbAdapter(this); | 
|  | mDbHelper.open(); | 
|  | fillData(); | 
|  | }</pre> | 
|  | <p>And be sure you have the <code>mDbHelper</code> field definition (right | 
|  | under the mNoteNumber definition): </p> | 
|  | <pre>    private NotesDbAdapter mDbHelper;</pre> | 
|  |  | 
|  | <h2>Step 9</h2> | 
|  |  | 
|  | <div class="sidebox-wrapper"> | 
|  | <div class="sidebox"> | 
|  | <h2>More about menus</h2> | 
|  | <p>The notepad application we are constructing only scratches the | 
|  | surface with <a href="{@docRoot}resources/faq/commontasks.html#addmenuitems">menus</a>. </p> | 
|  | <p>You can also <a href="{@docRoot}resources/faq/commontasks.html#menukeyshortcuts">add | 
|  | shortcut keys for menu items</a>, <a | 
|  | href="{@docRoot}resources/faq/commontasks.html#menukeyshortcuts">create | 
|  | submenus</a> and even <a href="{@docRoot}resources/faq/commontasks.html#addingtoothermenus">add | 
|  | menu items to other applications!</a>. </p> | 
|  | </div> | 
|  | </div> | 
|  |  | 
|  | <p>Fill out the body of the <code>onCreateOptionsMenu()</code> method.</p> | 
|  |  | 
|  | <p>We will now create the "Add Item" button that can be accessed by pressing the menu | 
|  | button on the device. We'll specify that it occupy the first position in the menu.</p> | 
|  |  | 
|  | <ol> | 
|  | <li> | 
|  | In <code>strings.xml</code> resource (under <code>res/values</code>), add | 
|  | a new string named "menu_insert" with its value set to <code>Add Item</code>: | 
|  | <pre><string name="menu_insert">Add Item</string></pre> | 
|  | <p>Then save the file and return to <code>Notepadv1</code>.</p> | 
|  | </li> | 
|  | <li>Create a menu position constant at the top of the  class: | 
|  | <pre>public static final int INSERT_ID = Menu.FIRST;</pre> | 
|  | </li> | 
|  | <li>In the <code>onCreateOptionsMenu()</code> method, change the | 
|  | <code>super</code> call so we capture the boolean return as <code>result</code>. We'll return this value at the end.</li> | 
|  | <li>Then add the menu item with <code>menu.add()</code>.</li> | 
|  | </ol> | 
|  | <p>The whole method should now look like this: | 
|  | <pre> | 
|  | @Override | 
|  | public boolean onCreateOptionsMenu(Menu menu) { | 
|  | boolean result = super.onCreateOptionsMenu(menu); | 
|  | menu.add(0, INSERT_ID, 0, R.string.menu_insert); | 
|  | return result; | 
|  | }</pre> | 
|  | <p>The arguments passed to <code>add()</code> indicate: a group identifier for this menu (none, | 
|  | in this case), a unique ID (defined above), the order of the item (zero indicates no preference), | 
|  | and the resource of the string to use for the item.</p> | 
|  |  | 
|  | <h2 style="clear:right;">Step 10</h2> | 
|  | <p>Fill out the body of the <code>onOptionsItemSelected()</code> method:</p> | 
|  | <p>This is going | 
|  | to handle our new "Add Note" menu item.  When this is selected, the | 
|  | <code>onOptionsItemSelected()</code> method will be called with the | 
|  | <code>item.getId()</code> set to <code>INSERT_ID</code> (the constant we | 
|  | used to identify the menu item). We can detect this, and take the | 
|  | appropriate actions:</p> | 
|  | <ol> | 
|  | <li> | 
|  | The <code>super.onOptionsItemSelected(item)</code> method call goes at the | 
|  | end of this method — we want to catch our events first!    </li> | 
|  | <li> | 
|  | Write a switch statement on <code>item.getItemId()</code>. | 
|  | <p>In the case of <var>INSERT_ID</var>, call a new method, <code>createNote()</code>, | 
|  | and return true, because we have handled this event and do not want to | 
|  | propagate it through the system.</p> | 
|  | </li> | 
|  | <li>Return the result of the superclass' <code>onOptionsItemSelected()</code> | 
|  | method at the end.</li> | 
|  | </ol> | 
|  | <p> | 
|  | The whole <code>onOptionsItemSelect()</code> method should now look like | 
|  | this:</p> | 
|  | <pre> | 
|  | @Override | 
|  | public boolean onOptionsItemSelected(MenuItem item) { | 
|  | switch (item.getItemId()) { | 
|  | case INSERT_ID: | 
|  | createNote(); | 
|  | return true; | 
|  | } | 
|  |  | 
|  | return super.onOptionsItemSelected(item); | 
|  | }</pre> | 
|  |  | 
|  | <h2>Step 11</h2> | 
|  | <p>Add a new <code>createNote()</code> method:</p> | 
|  | <p>In this first version of | 
|  | our application, <code>createNote()</code> is not going to be very useful. | 
|  | We will simply | 
|  | create a new note with a title assigned to it based on a counter ("Note 1", | 
|  | "Note 2"...) and with an empty body. At present we have no way of editing | 
|  | the contents of a note, so for now we will have to be content making one | 
|  | with some default values:</p> | 
|  | <ol> | 
|  | <li>Construct the name using "Note" and the counter we defined in the class: <code> | 
|  | String noteName = "Note " + mNoteNumber++</code></li> | 
|  | <li> | 
|  | Call <code>mDbHelper.createNote()</code> using <code>noteName</code> as the | 
|  | title and <code>""</code> for the body | 
|  | </li> | 
|  | <li> | 
|  | Call <code>fillData()</code> to populate the list of notes (inefficient but | 
|  | simple) — we'll create this method next.</li> | 
|  | </ol> | 
|  | <p> | 
|  | The whole <code>createNote()</code> method should look like this: </p> | 
|  | <pre> | 
|  | private void createNote() { | 
|  | String noteName = "Note " + mNoteNumber++; | 
|  | mDbHelper.createNote(noteName, ""); | 
|  | fillData(); | 
|  | }</pre> | 
|  |  | 
|  |  | 
|  | <h2>Step 12</h2> | 
|  | <div class="sidebox-wrapper"> | 
|  | <div class="sidebox"> | 
|  | <h2>List adapters</h2> | 
|  | <p>Our example uses a {@link android.widget.SimpleCursorAdapter | 
|  | SimpleCursorAdapter} to bind a database {@link android.database.Cursor Cursor} | 
|  | into a ListView, and this is a common way to use a {@link android.widget.ListAdapter | 
|  | ListAdapter}. Other options exist like {@link android.widget.ArrayAdapter ArrayAdapter} which | 
|  | can be used to take a List or Array of in-memory data and bind it in to | 
|  | a list as well.</p> | 
|  | </div> | 
|  | </div> | 
|  |  | 
|  | <p>Define the <code>fillData()</code> method:</p> | 
|  | <p>This | 
|  | method uses <code>SimpleCursorAdapter,</code> which takes a database <code>Cursor</code> | 
|  | and binds it to fields provided in the layout. These fields define the row elements of our list | 
|  | (in this case we use the <code>text1</code> field in our | 
|  | <code>notes_row.xml</code> layout), so this allows us to easily populate the list with | 
|  | entries from our database.</p> | 
|  | <p>To do this we have to provide a mapping from the <code>title</code> field in the returned Cursor, to | 
|  | our <code>text1</code> TextView, which is done by defining two arrays: the first a string array | 
|  | with the list of columns to map <em>from</em> (just "title" in this case, from the constant | 
|  | <code>NotesDbAdapter.KEY_TITLE</code>) and, the second, an int array | 
|  | containing references to the views that we'll bind the data <em>into</em> | 
|  | (the <code>R.id.text1</code> TextView).</p> | 
|  | <p>This is a bigger chunk of code, so let's first take a look at it:</p> | 
|  |  | 
|  | <pre> | 
|  | private void fillData() { | 
|  | // Get all of the notes from the database and create the item list | 
|  | Cursor c = mDbHelper.fetchAllNotes(); | 
|  | startManagingCursor(c); | 
|  |  | 
|  | String[] from = new String[] { NotesDbAdapter.KEY_TITLE }; | 
|  | int[] to = new int[] { R.id.text1 }; | 
|  |  | 
|  | // Now create an array adapter and set it to display using our row | 
|  | SimpleCursorAdapter notes = | 
|  | new SimpleCursorAdapter(this, R.layout.notes_row, c, from, to); | 
|  | setListAdapter(notes); | 
|  | }</pre> | 
|  |  | 
|  | <p>Here's what we've done:</p> | 
|  | <ol> | 
|  | <li> | 
|  | After obtaining the Cursor from <code>mDbHelper.fetchAllNotes()</code>, we | 
|  | use an Activity method called | 
|  | <code>startManagingCursor()</code> that allows Android to take care of the | 
|  | Cursor lifecycle instead of us needing to worry about it. (We will cover the implications | 
|  | of the lifecycle in exercise 3, but for now just know that this allows Android to do some | 
|  | of our resource management work for us.)</li> | 
|  | <li> | 
|  | Then we create a string array in which we declare the column(s) we want | 
|  | (just the title, in this case), and an int array that defines the View(s) | 
|  | to which we'd like to bind the columns (these should be in order, respective to | 
|  | the string array, but here we only have one for each).</li> | 
|  | <li> | 
|  | Next is the SimpleCursorAdapter instantiation. | 
|  | Like many classes in Android, the SimpleCursorAdapter needs a Context in order to do its | 
|  | work, so we pass in <code>this</code> for the context (since subclasses of Activity | 
|  | implement Context). We pass the <code>notes_row</code> View we created as the receptacle | 
|  | for the data, the Cursor we just created, and then our arrays.</li> | 
|  | </ol> | 
|  | <p> | 
|  | In the future, remember that the mapping between the <strong>from</strong> columns and <strong>to</strong> resources | 
|  | is done using the respective ordering of the two arrays. If we had more columns we wanted | 
|  | to bind, and more Views to bind them in to, we would specify them in order, for example we | 
|  | might use <code>{ NotesDbAdapter.KEY_TITLE, NotesDbAdapter.KEY_BODY }</code> and | 
|  | <code>{ R.id.text1, R.id.text2 }</code> to bind two fields into the row (and we would also need | 
|  | to define text2 in the notes_row.xml, for the body text). This is how you can bind multiple fields | 
|  | into a single row (and get a custom row layout as well).</p> | 
|  | <p> | 
|  | If you get compiler errors about classes not being found, ctrl-shift-O or | 
|  | (cmd-shift-O on the mac) to organize imports. | 
|  | </p> | 
|  |  | 
|  | <h2 style="clear:right;">Step 13</h2> | 
|  | <p>Run it! | 
|  | <ol> | 
|  | <li> | 
|  | Right click on the <code>Notepadv1</code> project.</li> | 
|  | <li> | 
|  | From the popup menu, select <strong>Run As</strong> > | 
|  | <strong>Android Application</strong>.</li> | 
|  | <li> | 
|  | If you see a dialog come up, select Android Launcher as the way of running | 
|  | the application (you can also use the link near the top of the dialog to | 
|  | set this as your default for the workspace; this is recommended as it will | 
|  | stop the plugin from asking you this every time).</li> | 
|  | <li>Add new notes by hitting the menu button and selecting <em>Add | 
|  | Item</em> from the menu.</li> | 
|  | </ol> | 
|  |  | 
|  | <h2 style="clear:right;">Solution and Next Steps</h2> | 
|  | <p>You can see the solution to this class in <code>Notepadv1Solution</code> | 
|  | from | 
|  | the zip file to compare with your own.</p> | 
|  |  | 
|  | <p>Once you are ready, move on to <a href="notepad-ex2.html">Tutorial | 
|  | Exercise 2</a> to add the ability to create, edit and delete notes.</p> | 
|  |  |