java - _ID不存在

Question

我正在尝试从幻灯片 bbdd 获取数据并将其显示在 ListView 中，但出现错误。

public class DataBaseHelper extends SQLiteOpenHelper{

    private static String DB_PATH = "/data/data/com.rbrlnx.lugares/databases/";
    private static final String DATABASE_NAME="db.db";
    SQLiteDatabase db;

     String CREATE_TABLE = "CREATE TABLE IF NOT EXISTS lugares (" +
     " _id INTEGER PRIMARY KEY AUTOINCREMENT, " +
     "nombre text," +
     "descripcion text,"+
     "latitud real," +
     "longitud real," +
     "foto String);";

 /*Primero se crea constructor, funcion onCreate, onUpgrade,Abrir y Cerrar*/

    public  DataBaseHelper(Context context){
      super(context,DATABASE_NAME,null,1);

    }

    public void onCreate(SQLiteDatabase db){
     try {
         openDataBase();
         db.execSQL(CREATE_TABLE);

     } catch (Exception e) {
        // handle exception
     }           
    }

public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {

}
    public void openDataBase() throws SQLException{

    //Open the database
    String myPath = DB_PATH + DATABASE_NAME;
    db = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);

    }    

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


/*Despues metodos para añadir y obtener datos*/

    public long addNombre(String nombre){

    ContentValues cv = new ContentValues();
    cv.put("nombre", nombre);
return db.insert("lugares", null, cv);           
}

     public long addDescripcion(String descripcion){

         ContentValues cv = new ContentValues();
            cv.put("descripcion", descripcion);
            return db.insert("lugares", null, cv);           

     }
     public long addLatitud(double latitud){

         ContentValues cv = new ContentValues();
            cv.put("latitud", latitud);
            return db.insert("lugares", null, cv);           

     }
     public long addLongitud(double longitud){

         ContentValues cv = new ContentValues();
            cv.put("longitud", longitud);
            return db.insert("lugares", null, cv);           

     }

     public long addFoto(String foto) {

         ContentValues cv = new ContentValues();
            cv.put("foto", foto);
            return db.insert("lugares", null, cv);           

        }


     public Cursor getNombres(){
         SQLiteDatabase db = this.getWritableDatabase();

            Cursor respuesta = db.rawQuery("select nombre from lugares", null);
           return respuesta;

       }







    }

和

public class listatab extends ListActivity{ 

    Context context;
    ListView listanombres;
    DataBaseHelper ayudabbdd;


  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);     
     DataBaseHelper ayudabbdd = new DataBaseHelper(this);
     Cursor nombresC;     
     nombresC = (Cursor) ayudabbdd.getNombres();  
     startManagingCursor(nombresC);
     if(nombresC!=null){
     ListAdapter adapter = new SimpleCursorAdapter(this, R.layout.listatab, nombresC, new String[] { "nombre" }, new int[] { R.id.lista });
     this.setListAdapter(adapter);
     this.getListView().setTextFilterEnabled(true);  

     }
  }
  @Override
protected void onDestroy() {
    super.onDestroy();
    if (ayudabbdd != null) {
        ayudabbdd.close();
    }
    }
  }

日志猫向我显示了这个错误:

10-11 00:55:49.930: ERROR/AndroidRuntime(32392): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.rbrlnx.lugares/com.rbrlnx.lugares.listatab}: java.lang.IllegalArgumentException: column '_id' does not exist
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.app.ActivityThread.startActivityNow(ActivityThread.java:1487)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:127)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:339)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:654)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.widget.TabHost.setCurrentTab(TabHost.java:326)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.widget.TabHost$2.onTabSelectionChanged(TabHost.java:132)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.widget.TabWidget$TabClickListener.onClick(TabWidget.java:456)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.view.View.performClick(View.java:2485)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.view.View$PerformClick.run(View.java:9080)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.os.Handler.handleCallback(Handler.java:587)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.os.Handler.dispatchMessage(Handler.java:92)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.os.Looper.loop(Looper.java:130)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at android.app.ActivityThread.main(ActivityThread.java:3683)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at java.lang.reflect.Method.invokeNative(Native Method)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at java.lang.reflect.Method.invoke(Method.java:507)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392):     at dalvik.system.NativeStart.main(Native Method)
10-11 00:55:49.930: ERROR/AndroidRuntime(32392): Caused by: java.lang.IllegalArgumentException: column '_id' does not exist

Answer 1

你的openDataBase()方法是非常错误的。您不应提供数据库的路径。数据库会为您创建并在 onCreate() 方法中传递给您。如果删除 openDataBase() 方法并且不从 onCreate() 调用它，并在 中设置 this.db = db >onCreate()，您可能会遇到此错误。

有关在 Android 中使用数据库的更多帮助，请参阅此 Android Database Tutorial 。祝你好运!