android – 即使没有在FirebaseListAdapter中填充的视图,如何关闭进度条？

我使用FirebaseUI FirebaseListAdapter.加载数据需要一些时间,我想显示一个旋转的圆圈.我可以通过在populateView中将视图可见性设置为不可见来忽略进度条,但如果没有要填充的视图则它不起作用.怎么办呢？

解决方法:

更新：FirebaseUI适配器现在有一个onDataChanged()方法,您可以覆盖该方法以检测何时完成加载一组数据.

见source code on github.从那里：

This method will be triggered each time updates from the database have been completely processed. So the first time this method is called, the initial data has been loaded – including the case when no data at all is available. Each next time the method is called, a complete update (potentially consisting of updates to multiple child items) has been completed.

You would typically override this method to hide a loading indicator (after the initial load) or to complete a batch update to a UI element.

FirebaseUI示例应用程序覆盖onDataChanged()以隐藏其“加载”指示符：

public void onDataChanged() {
    // If there are no chat messages, show a view that invites the user to add a message.
    mEmptyListMessage.setVisibility(getItemCount() == 0 ? View.VISIBLE : View.GONE);
}

原始答案

FirebaseUI列表适配器在内部使用Firebase ChildEventListener.此侦听器仅针对相关的子事件触发.如果没有孩子,则不会发生任何事件.

您可以通过将附加值侦听器附加到传递给适配器的引用/查询来检测此情况.

DatabaseReference list = mDatabase.child("messages");
showSpinner();
mAdapter = new FirebaseListAdapter<Message>(......, list) {
    void populateView(View view, Message message, int position) {
        // the first message was loaded
        hideSpinner();
    }
});
list.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        // the initial data is loaded (even if there was none)
        hideSpinner();
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        Log.w(TAG, "onCancelled", databaseError.toException());
    }
});

标签：firebaseui,android,firebase,firebase-realtime-database
来源： https://codeday.me/bug/20190917/1810213.html