检查密钥是否存在firebase Android [英] check if a key exist firebase Android

问题描述

我要检查Firebase数据库中是否存在密钥.因此，例如，我要查找键"upvotes"以查看其是否存在.

I want to check if a key exist in the firebase db. so for example, I want to look for the key "upvotes" to see if it exist or not.

这是一个范例，此处不存在"upvotes"键:

Here is an exmaple, "upvotes" key does not exist in here:

现在，我尝试检查键"upvotes"是否在此位置:

Now I my attempt to check if the key "upvotes" is at this location:

        Map<String, Object> newPost = (Map<String, Object>) ids.next().getValue();
            if(newPost.get("upvotes").toString().equals("upvotes")){
                disp_rate = newPost.get("upvotes").toString();
            }
            else
            {
                disp_rate = "0";
            }

我的尝试是错误的，所以如何检查此位置是否存在键"upvotes".

My attempt is wrong, so how do I check if the key "upvotes" exist at this location.

推荐答案

只需使用此布尔函数containsKey

所以...

boolean check_rate = newPost.containsKey("upvotes");

if(check_rate == true){
                String disp_rate = newPost.get("upvotes").toString();
                rate_count.setText(disp_rate);
            }
            else{
                System.out.println("FAILED");
            }

如果有人在投票方面存在相同问题，这将解决交易.

This will fix the transaction if anyone is having the same issue with upvotes.

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