Android: ListView con CheckBox, rellenado de la base de datos SQLite no funciona

Question

Como con otras publicaciones aquí, intento crear un ListView que incluya un CheckBox para cada fila, y use una base de datos SQLite para almacenar el estado actual del selección.

Comenzando con el ejemplo en http://appfulcrum.com/?p=351, que no funcionó del todo como está, creé una aplicación simple que crea la base de datos, la rellena con 20 elementos y muestra la lista.

Recupera con éxito el estado y almacena el estado de la selección.

PERO no muestra correctamente el estado CheckBox si lo cambio, vaya al otro extremo de la lista y retroceda. p.ej. si selecciono el primer CheckBox, me desplazo hacia abajo y vuelvo al inicio, el CheckBox ya no está configurado. Esto se está ejecutando en un teléfono Android con Android 2.1.

Si regreso a la pantalla principal, vuelvo a la lista, el CheckBox es correctamente configurado, por lo que la base de datos se ha actualizado.

El ejemplo extiende SimpleCursorAdapter, y getView() invoca setChecked() con verdadero o falso según corresponda en función del valor de la columna de selección en la tabla.

A continuación se muestran todas las fuentes.

sin duda me aprecian que se les dijo, "Duh, aquí está el problema ..."

CustomListViewDB.java

// src/CustomListViewDB.java 
package com.appfulcrum.blog.examples.listviewcustomdb; 

import android.app.ListActivity; 
import android.database.Cursor; 
import android.database.SQLException; 
import android.os.AsyncTask; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.ListView; 
import android.widget.Toast; 

public class CustomListViewDB extends ListActivity { 

    private ListView mainListView = null; 
    CustomSqlCursorAdapter adapter = null; 
    private SqlHelper dbHelper = null; 
    private Cursor currentCursor = null; 

    private ListView listView = null; 

    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.simple); 

     if (this.dbHelper == null) { 
      this.dbHelper = new SqlHelper(this); 

     } 

     listView = getListView(); 
     listView.setItemsCanFocus(false); 
     listView.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE); 
     //listView.setClickable(true); 

     Button btnClear = (Button) findViewById(R.id.btnClear); 
     btnClear.setOnClickListener(new OnClickListener() { 

      public void onClick(View v) { 
       Toast.makeText(getApplicationContext(), 
         " You clicked Clear button", Toast.LENGTH_SHORT).show(); 
       ClearDBSelections(); 
      } 
     }); 

     new SelectDataTask().execute(); 

     this.mainListView = getListView(); 

     mainListView.setCacheColorHint(0); 

    } 

    @Override 
    protected void onRestart() { 
     super.onRestart(); 
     new SelectDataTask().execute(); 
    } 

    @Override 
    protected void onPause() { 

     super.onPause(); 
     this.dbHelper.close(); 
    } 

    protected void ClearDBSelections() { 

     this.adapter.ClearSelections(); 

    } 

    private class SelectDataTask extends AsyncTask<Void, Void, String> { 

     protected String doInBackground(Void... params) { 

      try { 

       CustomListViewDB.this.dbHelper.createDatabase(dbHelper.dbSqlite); 
       CustomListViewDB.this.dbHelper.openDataBase(); 

       CustomListViewDB.this.currentCursor = CustomListViewDB.this.dbHelper 
         .getCursor(); 

      } catch (SQLException sqle) { 

       throw sqle; 

      } 
      return null; 
     } 

     // can use UI thread here 
     protected void onPostExecute(final String result) { 

      startManagingCursor(CustomListViewDB.this.currentCursor); 
      int[] listFields = new int[] { R.id.txtTitle }; 
      String[] dbColumns = new String[] { SqlHelper.COLUMN_TITLE }; 

      CustomListViewDB.this.adapter = new CustomSqlCursorAdapter(
        CustomListViewDB.this, R.layout.single_item, 
        CustomListViewDB.this.currentCursor, dbColumns, listFields, 
        CustomListViewDB.this.dbHelper); 
      setListAdapter(CustomListViewDB.this.adapter); 

     } 
    } 

} 

CustomSqlCursorAdapter.java

// src/CustomSqlCursorAdapter.java 

package com.appfulcrum.blog.examples.listviewcustomdb; 

import android.content.ContentValues; 
import android.content.Context; 
import android.database.Cursor; 
import android.database.SQLException; 
import android.util.Log; 
import android.view.LayoutInflater; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.CheckBox; 
import android.widget.CompoundButton; 
import android.widget.CompoundButton.OnCheckedChangeListener; 
import android.widget.SimpleCursorAdapter; 
import android.widget.TextView; 

public class CustomSqlCursorAdapter extends SimpleCursorAdapter { 
    private Context mContext; 

    private SqlHelper mDbHelper; 
    private Cursor mCurrentCursor; 

    public CustomSqlCursorAdapter(Context context, int layout, Cursor c, 
      String[] from, int[] to, SqlHelper dbHelper) { 
     super(context, layout, c, from, to); 
     this.mCurrentCursor = c; 
     this.mContext = context; 
     this.mDbHelper = dbHelper; 

    } 

    public View getView(int pos, View inView, ViewGroup parent) { 
     View v = inView; 
     if (v == null) { 
      LayoutInflater inflater = (LayoutInflater) mContext 
        .getSystemService(Context.LAYOUT_INFLATER_SERVICE); 
      v = inflater.inflate(R.layout.single_item, null); 
     } 

     if (!this.mCurrentCursor.moveToPosition(pos)) { 
      throw new SQLException("CustomSqlCursorAdapter.getView: Unable to move to position: "+pos); 
     } 

     CheckBox cBox = (CheckBox) v.findViewById(R.id.bcheck); 

     // save the row's _id value in the checkbox's tag for retrieval later 
     cBox.setTag(Integer.valueOf(this.mCurrentCursor.getInt(0))); 

     if (this.mCurrentCursor.getInt(SqlHelper.COLUMN_SELECTED_idx) != 0) { 
      cBox.setChecked(true); 
      Log.w("SqlHelper", "CheckBox true for pos "+pos+", id="+this.mCurrentCursor.getInt(0)); 
     } else { 
      cBox.setChecked(false); 
      Log.w("SqlHelper", "CheckBox false for pos "+pos+", id="+this.mCurrentCursor.getInt(0)); 
     } 
     //cBox.setOnClickListener(this); 
     cBox.setOnCheckedChangeListener(new OnCheckedChangeListener() { 

      @Override 
      public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) { 

       Log.w("SqlHelper", "Selected a CheckBox and in onCheckedChanged: "+isChecked); 

       Integer _id = (Integer) buttonView.getTag(); 
       ContentValues values = new ContentValues(); 
       values.put(SqlHelper.COLUMN_SELECTED, 
         isChecked ? Integer.valueOf(1) : Integer.valueOf(0)); 
       mDbHelper.dbSqlite.beginTransaction(); 
       try { 
        if (mDbHelper.dbSqlite.update(SqlHelper.TABLE_NAME, values, "_id=?", 
          new String[] { Integer.toString(_id) }) != 1) { 
         throw new SQLException("onCheckedChanged failed to update _id="+_id); 
        } 
        mDbHelper.dbSqlite.setTransactionSuccessful(); 
       } finally { 
        mDbHelper.dbSqlite.endTransaction(); 
       } 

       Log.w("SqlHelper", "-- _id="+_id+", isChecked="+isChecked); 
      } 
     }); 

     TextView txtTitle = (TextView) v.findViewById(R.id.txtTitle); 
     txtTitle.setText(this.mCurrentCursor.getString(this.mCurrentCursor 
       .getColumnIndex(SqlHelper.COLUMN_TITLE))); 

     return (v); 
    } 

    public void ClearSelections() { 
     this.mDbHelper.clearSelections(); 
     this.mCurrentCursor.requery(); 

    } 
} 

ListViewWithDBActivity.java

package com.appfulcrum.blog.examples.listviewcustomdb; 

import android.app.Activity; 
import android.os.Bundle; 

public class ListViewWithDBActivity extends Activity { 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 
    } 
} 

SqlHelper

// SqlHelper.java 

package com.appfulcrum.blog.examples.listviewcustomdb; 

import android.content.ContentValues; 
import android.content.Context; 
import android.database.Cursor; 
import android.database.SQLException; 
import android.database.sqlite.SQLiteDatabase; 
import android.database.sqlite.SQLiteOpenHelper; 
import android.database.sqlite.SQLiteQueryBuilder; 
import android.database.sqlite.SQLiteStatement; 
import android.util.Log; 

public class SqlHelper extends SQLiteOpenHelper { 
    private static final String DATABASE_PATH = "/data/data/com.appfulcrum.blog.examples.listviewcustomdb/databases/"; 

    public static final String DATABASE_NAME = "TODOList"; 

    public static final String TABLE_NAME = "ToDoItems"; 
    public static final int ToDoItems_VERSION = 1; 

    public static final String COLUMN_ID = "_id";    // 0 
    public static final String COLUMN_TITLE = "title";   // 1 
    public static final String COLUMN_NAME_DESC = "description";// 2 
    public static final String COLUMN_SELECTED = "selected"; // 3 
    public static final int COLUMN_SELECTED_idx = 3; 

    public SQLiteDatabase dbSqlite; 
    private Context mContext; 

    public SqlHelper(Context context) { 
     super(context, DATABASE_NAME, null, 1); 
     mContext = context; 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 
     createDB(db); 
    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     Log.w("SqlHelper", "Upgrading database from version " + oldVersion 
       + " to " + newVersion + ", which will destroy all old data"); 

     db.execSQL("DROP TABLE IF EXISTS ToDoItems;"); 

     createDB(db); 
    } 

    public void createDatabase(SQLiteDatabase db) { 
     createDB(db); 
    } 

    private void createDB(SQLiteDatabase db) { 
     if (db == null) { 
      db = mContext.openOrCreateDatabase(DATABASE_NAME, 0, null); 
     } 

     db.execSQL("CREATE TABLE IF NOT EXISTS ToDoItems (_id INTEGER PRIMARY KEY, title TEXT, " 
       +" description TEXT, selected INTEGER);"); 
     db.setVersion(ToDoItems_VERSION); 

     // 
     // Generate a few rows for an example 
     // 
     // find out how many rows already exist, and make sure there's some minimum 
     SQLiteStatement s = db.compileStatement("select count(*) from ToDoItems;"); 

     long count = s.simpleQueryForLong(); 
     for (int i = 0; i < 20-count; i++) { 
      db.execSQL("INSERT INTO ToDoItems VALUES(NULL,'Task #"+i+"','Description #"+i+"',0);"); 
     } 
    } 

    public void openDataBase() throws SQLException { 
     String myPath = DATABASE_PATH + DATABASE_NAME; 

     dbSqlite = SQLiteDatabase.openDatabase(myPath, null, 
       SQLiteDatabase.OPEN_READWRITE); 
    } 

    @Override 
    public synchronized void close() { 
     if (dbSqlite != null) 
      dbSqlite.close(); 

     super.close(); 
    } 

    public Cursor getCursor() { 
     SQLiteQueryBuilder queryBuilder = new SQLiteQueryBuilder(); 

     queryBuilder.setTables(TABLE_NAME); 

     String[] asColumnsToReturn = new String[] { COLUMN_ID, COLUMN_TITLE, 
       COLUMN_NAME_DESC, COLUMN_SELECTED }; 

     Cursor mCursor = queryBuilder.query(dbSqlite, asColumnsToReturn, null, 
       null, null, null, COLUMN_ID+" ASC"); 

     return mCursor; 
    } 

    public void clearSelections() { 
     ContentValues values = new ContentValues(); 
     values.put(COLUMN_SELECTED, 0); 
     this.dbSqlite.update(SqlHelper.TABLE_NAME, values, null, null); 
    } 
} 

Start.java

//src/Start.java 
package com.appfulcrum.blog.examples.listviewcustomdb; 

import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.widget.Button; 
import android.widget.Toast; 

public class Start extends Activity { 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     Button btnSimple = (Button) findViewById(R.id.btnSimple); 
     btnSimple.setOnClickListener(new OnClickListener() { 

      public void onClick(View v) { 

       Toast.makeText(getApplicationContext(), 
         " You clicked ListView From DB button", Toast.LENGTH_SHORT).show(); 

       Intent intent = new Intent(v.getContext(), CustomListViewDB.class); 
       startActivityForResult(intent, 0); 
      } 
     }); 

    } 
} 

diseño/main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:id="@+id/buttonlayout" android:orientation="vertical" 
    android:layout_width="fill_parent" android:layout_height="fill_parent" 
    android:gravity="left|top" android:paddingTop="2dp" 
    android:paddingBottom="2dp"> 

    <TextView android:id="@+id/txtTest" android:layout_width="fill_parent" 
     android:layout_height="wrap_content" android:textStyle="bold" 
     android:text="@string/app_name" android:textSize="15sp" 
     android:textColor="#FF0000" android:gravity="center_vertical" 
     android:paddingLeft="5dp"> 
    </TextView> 

    <Button android:id="@+id/btnSimple" 
     android:layout_width="fill_parent" 
     android:layout_height="wrap_content" 
     android:textSize="15sp" 
     android:text="Listview from DB" 
     android:textColor="#000000" 
     > 
    </Button> 

</LinearLayout> 

diseño/simple.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:orientation="vertical" android:layout_width="fill_parent" 
    android:layout_height="fill_parent"> 

    <LinearLayout android:id="@+id/buttonlayout" 
     android:orientation="horizontal" android:layout_width="fill_parent" 
     android:layout_height="wrap_content" android:height="32dp" 
     android:gravity="left|top" android:paddingTop="2dp" 
     android:paddingBottom="2dp"> 

     <LinearLayout android:id="@+id/buttonlayout2" 
      android:orientation="horizontal" android:layout_height="wrap_content" 
      android:gravity="left|center_vertical" android:layout_width="wrap_content" 
      android:layout_gravity="left|center_vertical"> 

      <TextView android:id="@+id/txtTest" 
       android:layout_width="fill_parent" 
       android:layout_height="fill_parent" android:textStyle="bold" 
       android:text="@string/list_header" android:textSize="15sp" 
       android:gravity="center_vertical" android:paddingLeft="5dp"> 
      </TextView> 

      <Button android:id="@+id/btnClear" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" android:text="Clear" 
       android:textSize="15sp" android:layout_marginLeft="10px" 
       android:layout_marginRight="10px" 
       android:layout_marginBottom="2px" 
       android:layout_marginTop="2px" android:height="15dp" 
       android:width="70dp"></Button> 
     </LinearLayout> 
    </LinearLayout> 

    <TableLayout android:id="@+id/TableLayout01" 
     android:layout_width="fill_parent" android:layout_height="fill_parent" 
     android:stretchColumns="*"> 
     <TableRow> 
      <ListView android:id="@android:id/list" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content"></ListView> 
     </TableRow> 

    </TableLayout> 

</LinearLayout> 

diseño/single_item.xml

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="fill_parent" android:layout_height="wrap_content" 
    android:orientation="horizontal" android:gravity="center_vertical"> 

    <CheckBox android:id="@+id/bcheck" 
       android:layout_width="wrap_content" 
       android:layout_height="fill_parent" /> 

     <TextView android:id="@+id/txtTitle" 
      android:layout_width="wrap_content" android:gravity="left|center_vertical" 
      android:layout_height="?android:attr/listPreferredItemHeight" 
      android:layout_alignParentLeft="true" 
      android:textSize="20sp" android:text="Test" 
      android:textStyle="bold" android:paddingLeft="5dp" 
      android:paddingRight="2dp" android:focusable="false" 
      android:focusableInTouchMode="false"></TextView> 
     <LinearLayout android:layout_width="fill_parent" 
      android:layout_height="wrap_content" android:orientation="horizontal" 
      android:gravity="right|center_vertical"> 
     </LinearLayout> 

</LinearLayout> 

valores/cuerdas.xml

<?xml version="1.0" encoding="utf-8"?> 
<resources> 
    <string name="hello">Hello World, ListViewWithDBActivity!</string> 
    <string name="app_name">ListViewWithDB</string> 
    <string name="list_header">List Headers</string> 
</resources> 

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    android:versionCode="1" android:versionName="1.0"  
    package="com.appfulcrum.blog.examples.listviewcustomdb"> 

    <application android:icon="@drawable/icon" 
     android:label="@string/app_name" 
     android:theme="@android:style/Theme.NoTitleBar"> 
     > 
     <activity android:name=".Start" android:label="@string/app_name"> 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 
       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
     <activity android:name=".CustomListViewDB"></activity> 
    </application> 

    <uses-sdk android:minSdkVersion="7" /> <!-- android 1.6 --> 
</manifest> 

Si usted quiere construir, arrojar algo arbitraria en icon.png estirable.

Gracias de antemano.

Answer 1

Las vistas en un ListView se reciclan, y esto suena como un problema con eso. Probablemente necesite invalidar su onCheckedChangedListener para que cuando lo haga setChecked() no llame inadvertidamente al oyente anterior. También podría haber otras ramificaciones del reciclaje, así que tenlo en cuenta.

Así que trate de:

cBox.setOnCheckedChangeListener(null); 
... 
cBox.setChecked(); 
... 
cBox.setOnCheckedChangeListner(<real listener); 

Answer 2

he encontrado la solución más completa para el problema fuera de las instalaciones.

En Android ListView with CheckBox : Retain State

Apreciar la gente de ayuda.