如何从Firebase获取所有Child的Java对象的ArrayList [英] How Can I get ArrayList of Java Objects of all Childs from Firebase

问题描述

如何使用更新的firebase命令从Firebase获取所有Child的Java对象的ArrayList，目前我正在使用下面的方法，但无法获取列表。

 ValueEventListener postListener = new ValueEventListener（）{
 @Override 
 public void onDataChange（DataSnapshot dataSnapshot）{
 //获取Post对象并使用值更新（DataSnapshot！= null）{
 for（DataSnapshot postSnapshot：dataSnapshot.getChildren（））{
 UserDataClass post = postSnapshot.getValue（UserDataClass.class）; 
 members.add（post）; 
 
 
 
 
 @Override 
 public void onCancelled（DatabaseError databaseError）{
 //获取发布失败，记录消息
 
} 
}; 
 mDatabaseRef.addValueEventListener（postListener）; 
  

下面是从firebase返回的datasnapshot，但我无法

  DataSnapshot {key = 12345，value = {Members = {00000000 = {phoneNo = 00000000，经度= 73.0703307，纬度= 33.6396975，密码= qwertyuiop，CName = 00000000，管理员=真，姓名= Anwar Kamal}，03028084374 = {phoneNo = 03028084374，经度= 73.0701292，纬度= 33.6397129，密码= qwerty，CName = 00000000，admin = false，name = Nehal Khan}，03028084516 = {phoneNo = 03028084516，经度= 73.0702659，纬度= 33.6397622，密码= qwerty，CName = 03035356317，admin = false， }}} 
  

我想要的是所有成员的列表

我的java对象是

  public class UserDataClass {
 public double纬度; 
公共经度; 
 public String Name =; 
 public String password =; 
 public String phoneNo =; 
 public String CircleName =; 
 public boolean isAdmin = false; 
 
  

解决方案 ValueEventListener 有另一个目的。
您应该使用 ChildEventListener 以及 dataSnapshop.getValue（）来实现您想要的内容，例如：

  ChildEventListener childEventListener = new ChildEventListener（）{
 @Override 
 public void onChildAdded（DataSnapshot dataSnapshot，String previousChildName）{
 
 UserDataClass post = postSnapshot.getValue（UserDataClass.class）; 
 members.add（post）; 
 
 
 
  

注意：
您应该使用当前 firebase_referance 到 Users 表的侦听器。因此你应该替换

$ $ $ $ $ $ $ mDatabaseRef.addValueEventListener（postListener）;

与

  mDatabaseRef.child（Members）。addChildEventListener（childEventListener）; 
  

请注意您的完整路径成员表是彩色的，我不能找到路径。

您可以找到整个文档这里

祝你好运

How Can I get ArrayList of Java Objects of all Childs from Firebase using updated firebase commands, currently I am using below approach but not able to get the list.

ValueEventListener postListener = new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                // Get Post object and use the values to update the UI

                if(dataSnapshot!=null){
                    for (DataSnapshot postSnapshot:        dataSnapshot.getChildren()) {
                        UserDataClass post =    postSnapshot.getValue(UserDataClass.class);
                        members.add(post);
                    }

                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                // Getting Post failed, log a message

            }
        };
        mDatabaseRef.addValueEventListener(postListener);

below is datasnapshot which is returning from firebase but I am not able to get the desired result out of it.

DataSnapshot { key = 12345, value = {Members={00000000={phoneNo=00000000, longitude=73.0703307, latitude=33.6396975, password=qwertyuiop, CName=00000000, admin=true, name=Anwar Kamal}, 03028084374={phoneNo=03028084374, longitude=73.0701292, latitude=33.6397129, password=qwerty, CName=00000000, admin=false, name=Nehal Khan}, 03028084516={phoneNo=03028084516, longitude=73.0702659, latitude=33.6397622, password=qwerty, CName=03035356317, admin=false, name=Jamal Khan}}} }

all i want is list of all members

and my java object is

public class UserDataClass {
     public double latitude;
     public double longitude;
     public String Name="";
     public String password="";
     public String phoneNo="";
     public String CircleName="";
     public boolean isAdmin=false;
}

解决方案

The ValueEventListener has another purpose. You should use ChildEventListener and also dataSnapshop.getValue() to implement what you want, for example:

ChildEventListener childEventListener = new ChildEventListener() {
    @Override
    public void onChildAdded(DataSnapshot dataSnapshot, String previousChildName) {

        UserDataClass post =    postSnapshot.getValue(UserDataClass.class);
        members.add(post);
    }

  //...

Note: You should use the listener with the current firebase_referance to the Users table. Hence you should replace

    mDatabaseRef.addValueEventListener(postListener);

with

    mDatabaseRef.child("Members").addChildEventListener(childEventListener);

notice that your full path of the Members table is colored and i couldn't figure the path.

You can find the whole documentation here

good luck

这篇关于如何从Firebase获取所有Child的Java对象的ArrayList的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！