问题检索Firebase的类似子元素 [英] Problem retrieve similar child element of firebase

问题描述

我想一次只检索日期和所有date元素，并将它们存储在firebase中的数组中，如下所示.

I want to retrieve only the date and all the date element at once and store them in array in the firebase as shown below.

我已使用以下代码进行检索，但未能成功.

i have used the following code to retrieve but failed to that.

    public void showData(View view) {

    final ArrayList<String> date = new ArrayList<>();
    firebaseDatabase = FirebaseDatabase.getInstance().getReference().child("Date");

    firebaseDatabase.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
            date.add(dataSnapshot.getValue().toString());
            display.setText(dataSnapshot.getValue().toString());
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });
}

请帮助找到解决方案.

推荐答案

正如@PeterHaddad在上一个答案中所说，访问已获取数据的顺序不正确.如果到目前为止没有其他帮助，您可以尝试这种方式.

As said by @PeterHaddad in the previous answer, the sequence to access the data you have taken is not right. You may try this way, if nothing else helped until yet.

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
rootRef.child("Names").orderByChild("Date").addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
       for(DataSnapshot ds: dataSnapshot.getChildren()){
        date.add(ds.getValue(String.class));
           }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {

    }
});

//Also as you've told that code is not working, please tell, what exactly is not working

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