如何从firebase中的值获取密钥-Howtogetthekeyfromthevalueinfirebase

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That's because you're using a ValueEventListener. If the query matches multiple children, it returns a list of all those children. Even if there's only a single matches child, it's still a list of one. And since you're calling getKey() on that list, you get the key of the location where you ran the query.

这是因为您正在使用ValueEventListener。如果查询匹配多个子节点，则返回所有这些子节点的列表。即使只有一个匹配的孩子，它仍然是一个列表。由于您在该列表中调用getKey()，因此您将获得运行查询的位置的键。

To get the key of the matches children, loop over the children of the snapshot:

要获取匹配子节点的键，请对快照的子节点进行循环:

mDatabase.child("clubs")
         .orderByChild("name")
         .equalTo("efg")
         .addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot childSnapshot: dataSnapshot.getChildren()) {
            String clubkey = childSnapshot.getKey();

But note that if you assume that the club name is unique, you might as well store the clubs under their name and access the correct one without a query:

但请注意，如果您假设俱乐部名称是唯一的，您不妨将俱乐部的名称存储在它们的名称下，并访问正确的名称，而无需查询:

mDatabase.child("clubs")
         .child("efg")
         .addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        String clubkey = dataSnapshot.getKey(); // will be efg