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这里是我的火力地堡数据Android的火力点 - 让儿童数
{
"ques": {
"Chemistry": {},
"Countries": {},
"Film": {},
"Geography": {},
"General Knowledge": {},
"Information Technology": {},
"Physics": {},
"Sports": {},
"Technology": {
"-Ki0y2ojhgAkDKVFostV": {},
"-Ki0ySAkiILNo2WSM7EO": {},
"-Ki1-8R-5gfHJGl9bDYC": {},
"-Ki1-fP2HlW0ejzVOGnD": {},
"-Ki1-vihF3xgP81UPT5t": {},
"-Ki10DSBPWIK0SAv5v8V": {},
"-Ki11-pLXVWZlv0XbKpp": {},
"-Ki11al-z6_MDBdpLGh7": {},
"-Ki11pxZvjvIl68UhVRc": {},
"-Ki124jOsYpy9bWpc7Yo": {},
"-Ki12oDiad-7X6UBTtBv": {},
"-Ki133GHJeys-J0vtdI9": {},
"-Ki13Iq62Ly_tx4tcxKa": {},
"-Ki13e4pp1Xnq7tnYa4N": {},
"-Ki142gU6ZHRkE34r0u3": {},
"-Ki14GswYf_lEji5a2PX": {},
"-Ki14WZpH5w5jnB4mZF1": {},
"-Ki14tX__g6VdmHJHi-g": {},
"-Ki15JghcU73RtW5zacV": {},
"-Ki15c91cOoRoR7h5aTL": {}
}
}
}
我想算键下可用数Technology
当我使用下面的代码,被数= 7,但有20个按键可在Technology
Query countQuery = countRef.child("ques").child("Technology");
countQuery.addChildEventListener(new ChildEventListener() {
@Override
public void onChildAdded(DataSnapshot dataSnapshot, String s) {
questionCount = (int) dataSnapshot.getChildrenCount();
tQuestionNoShow.setText(""+questionCount);
}
@Override
public void onChildChanged(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onChildRemoved(DataSnapshot dataSnapshot) {
}
@Override
public void onChildMoved(DataSnapshot dataSnapshot, String s) {
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
所以..如何实现它?
也许您可以使用addListenerForSingleValueEvent()侦听器来获取所有数据一次。然后,您可以使用快照通过getChildrenCount()来计算子节点。你试过了吗? – user2399432
这个问题已经在这里有一个答案:[Firebase安卓计数的儿童和存储在一个变量](http://stackoverflow.com/questions/41163512/firebase-android-count-children-and-store-it-in-一个变量?rq = 1) –