Question

我将一些代码放在一起以具有更新我的sql行的功能，但它不起作用。任何人都可以看看我的代码，让我知道我错在哪里？如有必要，我可以发布替代代码。这是我的对话框文件，它应该更新行：

class EditListItemDialog extends Dialog implements View.OnClickListener {
MyDB dba;
private View editText;
private DiaryAdapter adapter;




  //  public EditListItemDialog(Context context, List<String> fragment_monday) {         //first constructor
  //      super(context);
  //      this.fragment_monday = fragment_monday;
  //  }

@Override
protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);
setContentView(R.layout.edit_text_dialog);//here is your xml with EditText and 'Ok' and 'Cancel' buttons
View btnOk = findViewById(R.id.button_ok);
editText = findViewById(R.id.edit_text);
btnOk.setOnClickListener(this);

}

private List<String> fragment_monday;

public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
//Position is the number of the item clicked
//You can use your adapter to modify the item
adapter.getItem(position); //Will return the clicked item
}

public EditListItemDialog(Context context, DiaryAdapter adapter, int position) {
super(context);
this.fragment_monday = new ArrayList<String>();
this.adapter = adapter;
}






@Override
public void onClick(View v) {


fragment_monday.add(((TextView) v).getText().toString());//here is your updated(or not updated) text
adapter.notifyDataSetChanged();
dismiss();
try {
    saveItToDB();
} catch (Exception e) {
    e.printStackTrace();
}


}

private void saveItToDB() {
dba.updateDiaryEntry(((TextView) editText).getText().toString(), 1);
dba.close();
((TextView) editText).setText("");// TODO Auto-generated method stub

}
}

MyDB文件：

public class MyDB {
private static final String TABLE_NAME = null;
private static final String KEY_ID = null;
private SQLiteDatabase db;
private final Context context;
private final MyDBhelper dbhelper;



// Initializes MyDBHelper instance
public MyDB(Context c){

    context = c;
    dbhelper = new MyDBhelper(context, Constants.DATABASE_NAME, null,
                                        Constants.DATABASE_VERSION);

}


// Closes the database connection
public void close()
{
    db.close();

}

// Initializes a SQLiteDatabase instance using MyDBhelper
public void open() throws SQLiteException
{

    try {
        db = dbhelper.getWritableDatabase();
    } catch(SQLiteException ex) {
        Log.v("Open database exception caught", ex.getMessage());
        db = dbhelper.getReadableDatabase();
    }

}

// updates a diary entry (existing row)
    public boolean updateDiaryEntry(String title, long rowId)
    {

        ContentValues newValue = new ContentValues();
        newValue.put(Constants.TITLE_NAME, title);

        return db.update(Constants.TABLE_NAME, newValue, Constants.KEY_ID + "=" + rowId, null)>0;

    }

// Reads the diary entries from database, saves them in a Cursor class and returns     it from the method
public Cursor getdiaries()
{
    Cursor c = db.query(Constants.TABLE_NAME, null, null,
                        null, null, null, null);
    return c;
}


}

Answer 1

dba对象未初始化，您的try / catch会崩溃。用

初始化它

dba = new MyDB(context);

在您的EditListItemDialog构造函数中（取消注释并删除 List fragment_monday ），如下所示：

class EditListItemDialog extends Dialog implements View.OnClickListener {
MyDB dba;
private View editText;
private DiaryAdapter adapter;

public EditListItemDialog(Context context) {           
    super(context);
    dba = new MyDB(context);
}

Answer 2

将saveItToDB方法替换为：

private void saveItToDB() {
    dba.open();
    dba.updateDiaryEntry(((TextView) editText).getText().toString(), 1);
    dba.close();
    ((TextView) editText).setText("")
}

缺少dba.open（）。

用新数据更新sql行

2 个答案: