ANDROID：SQLite - ListView 2 Lines

Question

我想开始工作和理解SQlite，所以这就是为什么我开始尝试在android开发人员页面上理解和编程记事本教程。但在ListView中，它们只显示您创建的Note的标题，而不显示正文。所以我想在ListView项目中显示标题和正文。这里是我的代码：

的NoteActivity类：

public class NoteActivity extends ListActivity 
{ 
    private static final ArrayList<HashMap<String,String>> list = new ArrayList<HashMap<String,String>>(); 
    private static final int ACTIVITY_CREATE=0; 
    private static final int ACTIVITY_EDIT=1; 
    private static final int INSERT_ID = Menu.FIRST; 
    private static final int DELETE_ID = Menu.FIRST + 1; 
    private NotesDbAdapter mDbHelper; 


    Context ctx; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     ctx = this; 

     setContentView(R.layout.notepad_list); 
     mDbHelper = new NotesDbAdapter(this); 
     mDbHelper.open(); 
     fillData(); 

     registerForContextMenu(getListView()); 
    } 

    private void fillData() { 

     Cursor notesCursor = mDbHelper.fetchAllNotes(); 

     // Get all of the rows from the database and create the item list 
     notesCursor = mDbHelper.fetchAllNotes(); 
     startManagingCursor(notesCursor); 



     //This code works only to display the title in the ListView: 
     /* 
     // Create an array to specify the fields we want to display in the list (only TITLE) 
     String[] from = new String[]{NotesDbAdapter.KEY_TITLE}; 

     // and an array of the fields we want to bind those fields to (in this case just text1) 
     int[] to = new int[]{R.id.text1}; 

     // Now create a simple cursor adapter and set it to display 
     SimpleCursorAdapter notes =new SimpleCursorAdapter(this, R.layout.notes_row, notesCursor, from, to); 
     setListAdapter(notes); 
     */ 


     //Here I want to use a SimpleAdapter to display the title and body of the Note 
     SimpleAdapter adapter = new SimpleAdapter 
       (this, list, R.layout.custom_row_view, new String[] {"title","body"}, new int[] {R.id.text11,R.id.text2}); 


     HashMap<String,String> temp = new HashMap<String,String>(); 
     temp.put("title",NotesDbAdapter.KEY_TITLE); 
     temp.put("body", NotesDbAdapter.KEY_BODY); 
     list.add(temp); 

     setListAdapter(adapter); 

    } 


    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     super.onCreateOptionsMenu(menu); 
     menu.add(0, INSERT_ID,0, R.string.menu_insert); 
     return true; 
    } 

    @Override 
    public boolean onMenuItemSelected(int featureId, MenuItem item) { 

     switch(item.getItemId()) { 
      case INSERT_ID: 
       createNote(); 
       return true; 
     } 

     return super.onMenuItemSelected(featureId, item); 
    } 

    @Override 
    public void onCreateContextMenu(ContextMenu menu, View v, 
            ContextMenu.ContextMenuInfo menuInfo) { 
     super.onCreateContextMenu(menu, v, menuInfo); 

     menu.add(0,DELETE_ID,0,R.string.menu_delete); 
    } 

    @Override 
    public boolean onContextItemSelected(MenuItem item) { 

     switch (item.getItemId()){ 
      case DELETE_ID: 
       AdapterView.AdapterContextMenuInfo info = (AdapterView.AdapterContextMenuInfo) item.getMenuInfo(); 
       mDbHelper.deleteNote(info.id); 
       fillData(); 
       Toast.makeText(this,"Note deleted",Toast.LENGTH_SHORT).show(); 
       return true; 
     } 
     return super.onContextItemSelected(item); 
    } 

    private void createNote() { 
     Intent intent = new Intent(this, NoteEdit.class); 
     startActivityForResult(intent, ACTIVITY_CREATE); 


    } 

    @Override 
    protected void onListItemClick(ListView l, View v, int position, long id) { 
     super.onListItemClick(l, v, position, id); 

     super.onListItemClick(l, v, position, id); 
     Intent i = new Intent(this, NoteEdit.class); 
     i.putExtra(NotesDbAdapter.KEY_ROWID, id); 
     startActivityForResult(i, ACTIVITY_EDIT); 
    } 

    @Override 
    protected void onActivityResult(int requestCode, int resultCode, Intent intent) { 
     super.onActivityResult(requestCode, resultCode, intent); 
     fillData(); 

    } 

我使用的菜单按钮创建笔记，但你可以忽略它们的importat方法是“fillData（）”。我不明白为什么ListView显示两个字符串“titl”和“body”，而不是标题和正文的内容。

这里是我的NoteEdit类，我用它来创建/编辑手记：

public class NoteEdit extends Activity { 

    private EditText mTitleText; 
    private EditText mBodyText; 
    private Button confirmButton; 
    private Long mRowId; 
    private NotesDbAdapter mDbHelper; 


    @Override 
    protected void onCreate(Bundle savedInstanceState) 
    { 
     super.onCreate(savedInstanceState); 
     mDbHelper = new NotesDbAdapter(this); 
     mDbHelper.open(); 
     setContentView(R.layout.note_edit); 
     setTitle(R.string.edit_note); 

     mTitleText = (EditText) findViewById(R.id.title); 
     mBodyText = (EditText) findViewById(R.id.body); 
     confirmButton = (Button) findViewById(R.id.confirm); 

     mRowId = (savedInstanceState == null) ? null : 
       (Long) savedInstanceState.getSerializable(NotesDbAdapter.KEY_ROWID); 
     if (mRowId == null) { 
      Bundle extras = getIntent().getExtras(); 
      mRowId = extras != null ? extras.getLong(NotesDbAdapter.KEY_ROWID) 
        : null; 
     } 

     populateFields(); 

    } 

    public void confirmButton(View view) 
    { 
     switch (view.getId()){ 
      case R.id.confirm: 

       setResult(RESULT_OK); 
       finish(); 
     } 
    } 

    @Deprecated 
    private void populateFields() { 
     if (mRowId != null) { 
      Cursor note = mDbHelper.fetchNote(mRowId); 
      startManagingCursor(note); 
      mTitleText.setText(note.getString(
        note.getColumnIndexOrThrow(NotesDbAdapter.KEY_TITLE))); 
      mBodyText.setText(note.getString(
        note.getColumnIndexOrThrow(NotesDbAdapter.KEY_BODY))); 
     } 
    } 

    @Override 
    protected void onSaveInstanceState(Bundle outState) { 
     super.onSaveInstanceState(outState); 
     saveState(); 
     outState.putSerializable(NotesDbAdapter.KEY_ROWID, mRowId); 
    } 

    @Override 
    protected void onPause() { 
     super.onPause(); 
     saveState(); 
    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 
     populateFields(); 
    } 

    private void saveState() { 
     String title = mTitleText.getText().toString(); 
     String body = mBodyText.getText().toString(); 

     if (mRowId == null) { 
      long id = mDbHelper.createNote(title, body); 
      if (id > 0) { 
       mRowId = id; 
      } 
     } else { 
      mDbHelper.updateNote(mRowId, title, body); 
     } 
    } 
} 

在这里，我NotesDBAdapter类：

/** * 简单的笔记数据库访问辅助类。定义了记事本示例的基本CRUD操作 *，并且可以列出所有笔记以及 *检索或修改特定笔记。

*/ 公共类NotesDbAdapter {

private static final String DATABASE_NAME = "data"; 
private static final String DATABASE_TABLE = "notes"; 
private static final int DATABASE_VERSION = 2; 


public static final String KEY_TITLE = "title"; 
public static final String KEY_BODY = "body"; 
public static final String KEY_ROWID = "_id"; 

private static final String TAG = "NotesDbAdapter"; 

private DatabaseHelper mDbHelper; 
private SQLiteDatabase mDb; 


private static final String DATABASE_CREATE = 
    "create table notes (_id integer primary key autoincrement, " 
    + "title text not null, body text not null);"; 


private final Context mCtx; 


private static class DatabaseHelper extends SQLiteOpenHelper { 

    DatabaseHelper(Context context) { 

     super(context, DATABASE_NAME, null, DATABASE_VERSION); 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 

     db.execSQL(DATABASE_CREATE); 
    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     Log.w(TAG, "Upgrading database from version " + oldVersion + " to " 
       + newVersion + ", which will destroy all old data"); 
     db.execSQL("DROP TABLE IF EXISTS notes"); 
     onCreate(db); 
    } 
} 

/** 
* Constructor - takes the context to allow the database to be 
* opened/created 
* 
* @param ctx the Context within which to work 

*/ 
public NotesDbAdapter(Context ctx) { 
    this.mCtx = ctx; 
} 

/** 
* Open the notes database. If it cannot be opened, try to create a new 
* instance of the database. If it cannot be created, throw an exception to 
* signal the failure 
* 
* @return this (self reference, allowing this to be chained in an 
*   initialization call) 
* @throws android.database.SQLException if the database could be neither opened or created 
*/ 
public NotesDbAdapter open() throws SQLException { 
    mDbHelper = new DatabaseHelper(mCtx); 
    mDb = mDbHelper.getWritableDatabase(); 
    return this; 
} 

public void close() { 
    mDbHelper.close(); 
} 

/** 
* Create a new note using the title and body provided. If the note is 
* successfully created return the new rowId for that note, otherwise return 
* a -1 to indicate failure. 
* 
* @param title the title of the note 
* @param body the body of the note 

*/ 
public long createNote(String title, String body) { 
    ContentValues initialValues = new ContentValues(); 
    initialValues.put(KEY_TITLE, title); 
    initialValues.put(KEY_BODY, body); 

    return mDb.insert(DATABASE_TABLE, null, initialValues); 
} 

/** 
* Delete the note with the given rowId 
* @param rowId id of note to delete 
* @return true if deleted, false otherwise 
*/ 
public boolean deleteNote(long rowId) { 

    return mDb.delete(DATABASE_TABLE, KEY_ROWID + "=" + rowId, null) > 0; 
} 

/** 
* Return a Cursor over the list of all notes in the database 
* 
* @return Cursor over all notes 
*/ 
public Cursor fetchAllNotes() { 

    return mDb.query(DATABASE_TABLE, new String[] {KEY_ROWID, KEY_TITLE, 
      KEY_BODY}, null, null, null, null, null); 
} 

/** 
* Return a Cursor positioned at the note that matches the given rowId 
* @param rowId id of note to retrieve 
* @return Cursor positioned to matching note, if found 
* @throws android.database.SQLException if note could not be found/retrieved 
*/ 
public Cursor fetchNote(long rowId) throws SQLException { 

    Cursor mCursor = 

     mDb.query(true, DATABASE_TABLE, new String[] {KEY_ROWID, 
       KEY_TITLE, KEY_BODY}, KEY_ROWID + "=" + rowId, null, 
       null, null, null, null); 
    if (mCursor != null) { 
     mCursor.moveToFirst(); 
    } 
    return mCursor; 

} 

/** 
* Update the note using the details provided. The note to be updated is 
* specified using the rowId, and it is altered to use the title and body 
* values passed in 
* 
* @param rowId id of note to update 
* @param title value to set note title to 
* @param body value to set note body to 
* @return true if the note was successfully updated, false otherwise 
*/ 
public boolean updateNote(long rowId, String title, String body) { 
    ContentValues args = new ContentValues(); 
    args.put(KEY_TITLE, title); 
    args.put(KEY_BODY, body); 

    return mDb.update(DATABASE_TABLE, args, KEY_ROWID + "=" + rowId, null) > 0; 
} 

}

，因为我认为你不需要他们，我没有贴XML的文件，主要问题是 “fillData” 方法，我不知道如何发布从数据库2号线在ListView

我也尝试了一些其他的教程，但我不能设法得到它的工作

Answer 1

问题出在我所知道的fillData()方法中。您将列名作为值传入，而不是来自光标的实际值。

HashMap<String,String> temp = new HashMap<String,String>(); 
temp.put("title",NotesDbAdapter.KEY_TITLE); 
temp.put("body", NotesDbAdapter.KEY_BODY); 
list.add(temp); 

这似乎是不正确的。相反，你应该按照以下方式做一些事情;

private void fillData() { 
    // Get all of the rows from the database and create the item list 
    Cursor notesCursor = mDbHelper.fetchAllNotes(); 
    startManagingCursor(notesCursor); 

    // The list that will back our table, this could be turned into a member variable. 
    List<HashMap<String,String>> list = new ArrayList<HashMap<String,String>>(); 

    // Get the column indexes 
    int titleColumnIndex = notesCursor.getColumnIndex(NotesDbAdapter.KEY_TITLE); 
    int bodyColumnIndex = notesCursor.getColumnIndex(NotesDbAdapter.KEY_BODY); 

    // Iterate through all of the cursor rows to fill the adapter 
    while (notesCursor.moveToNext()) { 
     String title = notesCursor.getString(titleColumnIndex); 
     String body = notesCursor.getString(bodyColumnIndex); 

     HashMap<String,String> temp = new HashMap<String,String>(); 
     temp.put("title", title); 
     temp.put("body", body); 
     list.add(temp); 
    } 

    //Here I want to use a SimpleAdapter to display the title and body of the Note 
    SimpleAdapter adapter = new SimpleAdapter 
      (this, list, R.layout.custom_row_view, new String[] {"title","body"}, new int[] {R.id.text11,R.id.text2}); 
    setListAdapter(adapter); 
} 

欲了解更多有关Cursor你会在Android的数据库时，应注意使相当广泛使用它。

同样对于关于使用游标的可能更清晰的回答，请查看tutorial的section 4。