如何在片段上查看数据库中的数据

Question

我试图在片段上查看数据库中的数据，并使用TableRow查看数据。

我的代码设置数据库：

public class SqliteManager extends Activity {

public static final int VERSI_DATABASE= 1;
public static final String NAMA_DATABASE = "dbCrudSqlite";
public static final String NAMA_TABEL = "tbAgenda";

public static final String FIELD_ID = "_id";
public static final int POSISI_ID = 0;
public static final String FIELD_JUDUL = "judul";
public static final int POSISI_JUDUL = 1;
 public static final String FIELD_DESKRIPSI = "deskripsi";
 public static final int POSISI_DESKRIPSI = 2;
 public static final String FIELD_WAKTU = "waktu";
public static final int POSISI_WAKTU = 3;

public static final String[] FIELD_TABEL ={ SqliteManager.FIELD_ID, SqliteManager.FIELD_JUDUL, SqliteManager.FIELD_DESKRIPSI, SqliteManager.FIELD_WAKTU };

 private Context crudContext;
 private SQLiteDatabase crudDatabase;
private SqliteManagerHelper crudHelper;

private static class SqliteManagerHelper extends SQLiteOpenHelper {
    private static final String BUAT_TABEL =
        "create table " + NAMA_TABEL + " (" +
        SqliteManager.FIELD_ID + " integer primary key autoincrement, " +
        SqliteManager.FIELD_JUDUL + " text not null, " +
        SqliteManager.FIELD_DESKRIPSI + " text not null," +
        SqliteManager.FIELD_WAKTU + " text not null " +
        ");";

    public SqliteManagerHelper(Context context) {
        super(context, NAMA_DATABASE, null, VERSI_DATABASE);
    }

    @Override
    public void onCreate(SQLiteDatabase database) {
        database.execSQL(BUAT_TABEL);
    }

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

}


public void generateData(SQLiteDatabase database){
    ContentValues cv=new ContentValues();
    cv.put(FIELD_ID, "3");
    cv.put(FIELD_JUDUL, "Abang");
    cv.put(FIELD_DESKRIPSI, "Abang");
    cv.put(FIELD_WAKTU, "Merah");
    database.insert(NAMA_TABEL,null,cv);

    cv.put(FIELD_ID, "2");
    cv.put(FIELD_JUDUL, "Opo");
    cv.put(FIELD_DESKRIPSI, "Opo");
    cv.put(FIELD_WAKTU, "Apa");
    database.insert(NAMA_TABEL,null,cv);
}

public SqliteManager(Context context) {
    crudContext = context;
}

public void bukaKoneksi() throws SQLException {
    crudHelper = new SqliteManagerHelper(crudContext);
    crudDatabase = crudHelper.getWritableDatabase();
    generateData(crudDatabase);
}

public void tutupKoneksi() {
    crudHelper.close();
    crudHelper = null;
    crudDatabase = null;
}

public long insertData(ContentValues values) {
    return crudDatabase.insert(NAMA_TABEL, null, values);
}

public boolean updateData(long rowId, ContentValues values) {
    return crudDatabase.update(NAMA_TABEL, values,
            SqliteManager.FIELD_ID + "=" + rowId, null) > 0;
}

public boolean hapusData(long rowId) {
    return crudDatabase.delete(NAMA_TABEL,
            SqliteManager.FIELD_ID + "=" + rowId, null) > 0;
}

public Cursor bacaData() {
    return crudDatabase.query(NAMA_TABEL,FIELD_TABEL,null, null, null, null,SqliteManager.FIELD_JUDUL + " DESC");
}

public Cursor bacaDataTerseleksi(long rowId) throws SQLException {
    Cursor cursor = crudDatabase.query(true, NAMA_TABEL,FIELD_TABEL,FIELD_ID + "=" + rowId,null, null, null, null, null);
    cursor.moveToFirst();
    return cursor;
}

public ContentValues ambilData(String tempat, String lat, String lng) {
    ContentValues values = new ContentValues();
    values.put(SqliteManager.FIELD_JUDUL, tempat);
    values.put(SqliteManager.FIELD_DESKRIPSI, lat);
    values.put(SqliteManager.FIELD_WAKTU, lng);
    return values;
}

public ArrayList<ArrayList<Object>> ambilSemuaBaris(){
    ArrayList<ArrayList<Object>> dataArray = new ArrayList<ArrayList<Object>>();
    Cursor cur;
    try
    {
        cur = crudDatabase.query(NAMA_TABEL, new String[]{FIELD_ID,FIELD_JUDUL,FIELD_DESKRIPSI}, null, null, null, null, null);
        cur.moveToFirst();
        if (!cur.isAfterLast())
        {
            do {
                ArrayList<Object> dataList = new ArrayList<Object>();
                dataList.add(cur.getLong(0));
                dataList.add(cur.getString(1));
                dataList.add(cur.getString(2));
                dataArray.add(dataList);
            }while (cur.moveToNext());
        }
    }catch (Exception e)
    {
        e.printStackTrace();
        Log.e("DB ERROR",e.toString());
    }
    return dataArray;
}
}

我想查看片段的数据：

public class JawaIndo extends Fragment {
private SqliteManager sqliteDB;
private Activity activity;
TextView bhsjawa,bhsindo;
Button addBtn;
TableLayout tabel4data;

public JawaIndo(){}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {

    View rootView = inflater.inflate(R.layout.jawaindo, container, false);
    sqliteDB = new SqliteManager(getActivity());
    sqliteDB.bukaKoneksi();

    activity = new Activity();

    tabel4data = (TableLayout) activity.findViewById(R.id.tabel_data);
    bhsjawa = (TextView) activity.findViewById(R.id.nama_id);
    bhsindo = (TextView) activity.findViewById(R.id.hobi_id);
    updateTable();

    return rootView;
}

protected void updateTable() {
    while (tabel4data.getChildCount()>1){
        tabel4data.removeViewAt(1);
    }
    ArrayList<ArrayList<Object>> data = sqliteDB.ambilSemuaBaris();
    for (int posisi = 0; posisi < data.size(); posisi++) {
        TableRow tabelBaris = new TableRow(getActivity());
        ArrayList<Object> baris = data.get(posisi);

        TextView idTxt = new TextView(getActivity());
        idTxt.setText(baris.get(0).toString());
        tabelBaris.addView(idTxt);

        TextView namaTxt = new TextView(getActivity());
        namaTxt.setText(baris.get(1).toString());
        tabelBaris.addView(namaTxt); 

        TextView hobiTxt = new TextView(getActivity());
        hobiTxt.setText(baris.get(2).toString());
        tabelBaris.addView(hobiTxt);
        tabel4data.addView(tabelBaris);
    }
}
}

在类JawaIndo上编写此代码时出错：

    activity = new Activity();
    tabel4data = (TableLayout) activity.findViewById(R.id.tabel_data);
    bhsjawa = (TextView) activity.findViewById(R.id.nama_id);
    bhsindo = (TextView) activity.findViewById(R.id.hobi_id);
    updateTable();

Answer 1

您只需更改onCreateView()方法中的一些内容：

它应该是

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
    Bundle savedInstanceState) {

  View rootView = inflater.inflate(R.layout.jawaindo, container, false);
  sqliteDB = new SqliteManager(getActivity());
  sqliteDB.bukaKoneksi();

  //activity = new Activity();

  // Update Here
  tabel4data = (TableLayout) rootView .findViewById(R.id.tabel_data);
  bhsjawa = (TextView) rootView .findViewById(R.id.nama_id);
  bhsindo = (TextView) rootView .findViewById(R.id.hobi_id);
  updateTable();

  return rootView;
}

在这个过程中，将视图的名为rootView的对象作为引用传递，以查找UI元素的id。

Answer 2

没有阅读所有的代码，只读了突出显示的片段和logcat，甚至还发现了多个问题：

• 当您试图从generateData()调用onCreateView()时，约束就失败了。当再次运行代码时，将重新插入相同的数据，导致约束失败。
• 然后，在这里： tabel4data = (TableLayout) activity.findViewById(R.id.tabel_data)；bhsjawa = (TextView) activity.findViewById(R.id.nama_id)；bhsindo = (TextView) activity.findViewById(R.id.hobi_id)；updateTable()； 您不应该使用new实例化活动。现在，所有这些findViewById()都将返回null，并在稍后的updateTable()中为您提供一个NullPointerException。

Answer 3

您无法从活动实例中获得对您的引用。它将永远只从View获得。View类负责初始化和查找屏幕中的视图。因此，始终通过布局找到您的视图。

这是您的代码：

activity = new Activity();
tabel4data = (TableLayout) activity.findViewById(R.id.tabel_data);
bhsjawa = (TextView) activity.findViewById(R.id.nama_id);
bhsindo = (TextView) activity.findViewById(R.id.hobi_id);
updateTable();

请按以下方式更改。将activity的引用更改为rootView

  activity = new Activity();  
  tabel4data = (TableLayout) rootView .findViewById(R.id.tabel_data);
  bhsjawa = (TextView) rootView .findViewById(R.id.nama_id);
  bhsindo = (TextView) rootView .findViewById(R.id.hobi_id);
  updateTable();