如何绕过唯一的ID和检索多个自动生成的孩子 [英] How to bypass unique ID and retrieve multiple auto generated child

问题描述

我想用一个自动生成的子项（Estab_url子项）来检索多个子项。这是我的代码。所有我可以检索的是一个孩子和它的随机

  final DatabaseReference establishments = database.getReference（establishments）; 
 
 
 setsments.child（s2）.child（Estab_url）。addChildEventListener（new ChildEventListener（）{
 @Override 
 public void onChildAdded（DataSnapshot dataSnapshot， String s）{
 if（dataSnapshot.hasChildren（））{
 // String value = dataSnapshot.getValue（String.class）; 
 String sd = dataSnapshot.getKey（）; 
 Name.setText（sd）; 
} 
 
} 
 
 @Override 
 public void onChildChanged（DataSnapshot dataSnapshot，String s）{
 
 
 $ b @Override 
 public void onChildRemoved（DataSnapshot dataSnapshot）{
 
} 
 
 @Override 
 public void onChildMoved（DataSnapshot dataSnapshot，String s）{
} 
 
 @Override 
 public void onCancelled（DatabaseError da tabaseError）{
 
} 
}）; 
  

解决方案

如果您正在阅读每个孩子：

$ p $ establishments.child（s2）.child（Estab_url）。addChildEventListener（new ChildEventListener（）{
@Override
public void onChildAdded（DataSnapshot dataSnapshot，String s）{
String url = dataSnapshot.child（url）。getValue（String.class）;
Name.setText url）;
}


如果这不是您要查找的内容，请更新您的问题重新解释了这个问题。

更新

要捕获列表中的所有URL，您需要在侦听器外部设置列表，然后将每个URL添加到列表中。

  List< String> urls = new LinkedList< String>（）; 
 establishments.child（s2）.child（Estab_url）。addChildEventListener（new ChildEventListener（）{
 @Override 
公共void onChildAdded（DataSnapshot dataSnapshot，String s）{
 String url = dataSnapshot.child（url）。getValue（String.class）; 
 urls.add（url）; 
 // TODO：使用URL的最新列表做一些事情
 
 code 
 
 
 
但请注意，您仍然无法使用侦听器的外部列表。任何需要列表最新内容的代码，都需要从内部调用/触发（在本例中） onChildAdded 。
 
I want to retrieve multiple child with an auto generated child(Estab_url child). Here is my Code. All i can retrieve is one child and its random

final DatabaseReference establishments = database.getReference("establishments");


  establishments.child(s2).child("Estab_url").addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                if (dataSnapshot.hasChildren()) {
                 //   String value = dataSnapshot.getValue(String.class);
                    String sd = dataSnapshot.getKey();
                    Name.setText(sd);
                }

            }

            @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) {

            }
        });

解决方案
If you're looking to read the URL value for each child:
establishments.child(s2).child("Estab_url").addChildEventListener(new ChildEventListener() {
    @Override
    public void onChildAdded(DataSnapshot dataSnapshot, String s) {
        String url = dataSnapshot.child("url").getValue(String.class);
        Name.setText(url);
    }
If that is not what you're looking for, please update your question to rephrase the problem.

Update

If you'd like to catch all URLs in a list, you'd set up the list outside of the listener and then add each URL to it as it comes in:
List<String> urls = new LinkedList<String>();
establishments.child(s2).child("Estab_url").addChildEventListener(new ChildEventListener() {
    @Override
    public void onChildAdded(DataSnapshot dataSnapshot, String s) {
        String url = dataSnapshot.child("url").getValue(String.class);
        urls.add(url);
        // TODO: do something with the up-to-date list of URLs
    }
But note that you still cannot use the list outside of the listener. Any code that needs the up-to-date content of the list, will need to be called/triggered from within (in this case) onChildAdded.

                        
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