Java 如何在片段上查看数据库中的数据

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;
}
}

---

没有阅读所有代码，只是突出显示的代码片段和logcat，甚至发现了多个问题：

• 当您试图从

  onCreateView（）

  调用

  generateData（）

  时，约束失败。再次运行代码时，会重新插入相同的数据，导致约束失败

• 然后，在这里：

  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();
  

  永远不要用

  new

  实例化活动。现在，所有这些

  findViewById（）

  s将返回

  null

  ，并在以后的

  updateTable（）

  中为您获取

  null点异常
  

---

您刚刚更改了onCreateView（）方法中的一些内容：

应该是这样

@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;
}

---

在此过程中，您的视图的对象名为rootView，用于查找UI元素的id。

您无法从活动实例中获取对的引用。它将始终仅从

视图中获取。
视图
类负责初始化并在屏幕中查找视图。因此，始终只按布局查找视图

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();

更改如下。将
活动的引用更改为
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();

错误是什么？请发布logcat。非常感谢，我的应用程序正在运行。
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();

  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();