Question

我正在尝试从数据库中检索数据。我没有收到任何错误，但数据未显示。这是我的代码：

DbHelper

public class DbHelper extends SQLiteOpenHelper{

static final String tag="dbHelper";

static final String DB_NAME="dianaaaa.db";
static final int DB_VERSION=1;
static final String TABLE_JOBS="jobs";
static final String C_START="start";
static final String C_STOP="stop";
static final String C_ID_J=BaseColumns._ID;
Context context;
SQLiteDatabase db;



public DbHelper(Context context) {
    super(context, DB_NAME, null, DB_VERSION);
    // TODO Auto-generated constructor stub
    this.context=context;
}

@Override
public void onCreate(SQLiteDatabase db) {

String sql2="create table "+TABLE_JOBS+"( "+C_ID_J+" INTEGER PRIMARY KEY, "+C_START+" text, "+C_STOP+" text)";

    try{
        db.execSQL(sql2);   
    }
    catch(SQLException e){
        Log.d(tag, "no");
    }finally{

    }

}

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

    db.execSQL("drop table if exists "+TABLE_JOBS);
    Log.d(tag, "onUpdated");
    onCreate(db);

}


public void insertJStart(String s1){
    SQLiteDatabase db = (SQLiteDatabase) getWritableDatabase();


    ContentValues values=new ContentValues();
    values.clear();
    values.put(DbHelper.C_START, s1);
    try{


    db.insertOrThrow(TABLE_JOBS, C_START, values);

    }catch(SQLException e){
        Log.d(tag, "nu vreau....");

    }finally{

    db.close();
    }
}

public void insertJStop(String s2){
    SQLiteDatabase db=(SQLiteDatabase) getWritableDatabase();

    ContentValues values=new ContentValues();

    values.clear();
    values.put(DbHelper.C_STOP, s2);
    db.insertOrThrow(TABLE_JOBS, C_STOP, values);

    db.close();
}


public Cursor getCursor(){
    SQLiteQueryBuilder queryBuilder=new SQLiteQueryBuilder();
    queryBuilder.setTables(TABLE_JOBS);

    String[] asColumToRetrun=new String[] { C_ID, C_START, C_STOP};


    Cursor mCursor=db.query(TABLE_JOBS, asColumToRetrun, null, null, null, null, "time ASC");

    return mCursor;
}

public String getDate(Cursor c, int i){

    return (c.getString(i));
}




public Cursor getAll(){

    db=this.getReadableDatabase();
    Cursor c=db.rawQuery("SELECT * FROM jobs ", new String[]{});
    return c;
}
}

的活动：

public class TimerDB extends Activity{

static final String tag="TimerDB";

private ListView list;
MyAdapter aa=null;
private Cursor cursor=null;
private DbHelper helper=null;

final ArrayList<String> aList=new ArrayList<String>();

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.times);

    list=(ListView)findViewById(R.id.timeList);

    helper=new DbHelper(this);
    cursor=helper.getAll();
    cursor.moveToNext();
    startManagingCursor(cursor);
    aa=new MyAdapter(cursor);
    list.setAdapter(aa);

}

class MyAdapter extends CursorAdapter{
    MyAdapter(Cursor c){
        super(TimerDB.this, c);
    }

    public View getView(int position, View convertView, ViewGroup parent){

        View row=convertView;

        if(row==null){
            LayoutInflater inflater=getLayoutInflater();
            row=inflater.inflate(R.layout.row, null);
        }
        return (row);

    }

    @Override
    public void bindView(View row, Context context, Cursor c) {
        // TODO Auto-generated method stub
        Holder holder=(Holder) row.getTag();
        holder.populateFrom(c, helper);

        c.moveToNext();

    }

    @Override
    public View newView(Context context, Cursor c, ViewGroup parent) {
        // TODO Auto-generated method stub

        LayoutInflater inflater=getLayoutInflater();
        View row=inflater.inflate(R.layout.row, parent, false);
        Holder holder=new Holder(row);
        row.setTag(holder);
        return row;
    }   
}

static class Holder {
    private TextView id, start, stop;   

    Holder(View row){
        id=(TextView) row.findViewById(R.id.rowViewStart);
        start=(TextView) row.findViewById(R.id.rowViewStart);
        stop=(TextView) row.findViewById(R.id.rowViewStop);
    }
    void populateFrom(Cursor c, DbHelper db){
        id.setText(db.getDate(c, 0));
        start.setText(db.getDate(c, 1));
        stop.setText(db.getDate(c, 2));
    }
}

}

Answer 1

在您的自定义适配器中，您要么实施getView()方法，要么实施newView()和bindView()方法（但不能与getView()一起实施）。现在你实现了这两个方法，但也override getView()，你可以从这些方法“覆盖”你的适配器实现。只需离开newView()和bindView()，然后移除getView()方法。

如果查看android源代码，在游标适配器的情况下，getView()方法将行创建委托给那些方法（它为newView()对象调用View并且然后bindView()绑定游标中的数据。

编辑：

- 也不要拨打c.moveToNext();，Cursor将始终正确定位。

为什么我的数据没有显示？

1 个答案: