Question

我在数据库中有数据： database in firebase

我想要阅读所有孩子（Belgia，Czechy，Polska ......）并在文本字段中显示它，但是点击按钮后（我不更改数据库中的数据）。该按钮分配了以下功能：

augroup my_changelist
    au!
    au BufWinLeave * call s:get_change_position()
    au BufWinEnter * call s:restore_change_position()
augroup END

fu! s:get_change_position() abort
    let changelist = split(execute('changes'), "\n")
    let b:my_change_position = {
                             \   'idx': index(changelist, matchstr(changelist, '^>.*')),
                             \   'view': winsaveview(),
                             \ }
    if b:my_change_position.idx == -1
        let b:my_change_position.idx = 100
    endif
endfu

fu! s:restore_change_position() abort
    if exists('b:my_change_position.idx') && exists('b:my_change_position.view')
        sil! exe 'norm! 99g;'. (b:my_change_position.idx - 1) .'g,'
        call winrestview(b:my_change_position.view)
    endif
endfu

Befrore我在代码中写道：

public void f_btn_zaczytaj_dane(View view) {
    myRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String value = dataSnapshot.getValue(String.class);
            TextView txt_opis_panstwa = (TextView) findViewById(R.id.txt_opis_panstwa);
            txt_opis_panstwa.setText(value);
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

}

不幸的是，当我按下按钮时没有任何反应。

我将非常感谢你的帮助此致，Marcin

Answer 1

你必须遍历你的孩子

public void f_btn_zaczytaj_dane(View view) {
    myRef.addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            TextView txt_opis_panstwa = (TextView) findViewById(R.id.txt_opis_panstwa);
            for (DataSnapshot country : dataSnapshot.getChildren()) {
             txt_opis_panstwa.append(country.getKey());
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

}

Answer 2

请使用此代码：

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference krajRef = rootRef.child("flagiistolice").child("kraj");

public void f_btn_zaczytaj_dane(View view) {
    ValueEventListener eventListener = new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            TextView txt_opis_panstwa = (TextView) findViewById(R.id.txt_opis_panstwa);
            for(DataSnapshot ds : dataSnapshot.getChildren()) {
                String country = ds.getkey();
                txt_opis_panstwa.append(country);
                Log.d("TAG", country);
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {}
    };
    krajRef.addListenerForSingleValueEvent(eventListener);
}

firebase，数据库，android studio：不从firebase数据库读取数据

2 个答案: