在我的 Android 应用中，我使用 Google Firebase 在数据库中存储信息。
我需要迭代信息，并且正在使用下面的for循环
public void showDataLobReq(DataSnapshot dataSnapshot){
for(DataSnapshot ds : dataSnapshot.child("Lobby_Requests").getChildren()){
System.out.println("asdfasdfasdfasdfasdf"+ds.getValue());
game = ds.child(userID).child("game").getValue(String.class);
console = ds.child(userID).child("console").getValue(String.class);
mic = ds.child(userID).child("mic").getValue(String.class);
players = ds.child(userID).child("players").getValue(String.class);
}
}
您可能会注意到我将“.child("Lobby_Requests")”放在 dataSnapshot 之后。这是因为 dataSnapshot 拍摄了整个数据库的快照，因此我必须进入子目录“Lobby_Requests”，因为那是我需要迭代的信息所在的位置。
将这个“.child()”放入是有问题的。
我将 dataSnapshot 在 for 循环的第一行中包含的内容打印到控制台，并使用 .child("Lobby_Requests") 从实际数据库中的目录“Lobbys”中提取信息，这是一个完全不同的目录。
然而，当我完全删除“.child()”时，它会给我一个整个数据库的 View ，就像它应该的那样。为什么要这样做？
监听器代码:
nRef = mFirebaseDatabase.getReference();
nRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
if (dataSnapshot.exists()){
showDataLobReq(dataSnapshot);
} else {
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
}
});
这是 JSON:
{
"Games" : {
"Forza 6" : {
"Consoles" : {
"PC" : true,
"Xbox 1" : true,
"Xbox 360" : true
},
"FilePathName" : "forza6",
"Genres" : {
"Racing" : true
},
"Live Lobbies" : 0,
"Name" : "Forza 6"
},
"Minecraft" : {
"Consoles" : {
"PC" : true,
"Xbox 1" : true,
"Xbox 360" : true
},
"FilePathName" : "minecraft",
"Genres" : {
"Adventure" : true,
"Creation" : true,
"Open World" : true
},
"Live Lobbies" : 0,
"Name" : "Minecraft"
}
},
"Lobbies" : {
"Cd6lVd2XMUYoLH6b0xoHsrfXMud2" : {
"Messages" : {
"-Kq6-1HsMvElEXZZyCIk" : {
"messageText" : "hey",
"messageTime" : 1501208519771,
"messageUser" : ""
}
},
"console" : "Origin",
"game" : "Minecraft",
"leader" : "Cd6lVd2XMUYoLH6b0xoHsrfXMud2",
"mic" : "Mic",
"note" : "2345",
"players" : "4"
},
"KUWH5f1TmYfO1O1wgCJLli3XZFi2" : {
"console" : "Steam",
"game" : "Forza 6",
"mic" : "No Mic",
"note" : "Hey Join Here!",
"players" : "2"
},
"hpWkq0D8clPReUetOq9Xtmc4V582" : {
"Messages" : {
"-Kq5a0kX305lFCRTSM_G" : {
"messageText" : "hello",
"messageTime" : 1501201701014,
"messageUser" : ""
},
"-Kq5asufOWQwtmyNJrQ7" : {
"messageText" : "hey",
"messageTime" : 1501201926941,
"messageUser" : ""
}
},
"console" : "Xbox One",
"game" : "Minecraft",
"leader" : "hpWkq0D8clPReUetOq9Xtmc4V582",
"mic" : "Mic",
"note" : "kjhg",
"players" : "4"
}
},
"Lobby_Requests" : {
"Cd6lVd2XMUYoLH6b0xoHsrfXMud2" : {
"Cd6lVd2XMUYoLH6b0xoHsrfXMud2" : {
"console" : "Xbox One",
"game" : "Forza 6",
"mic" : "Mic",
"players" : "5"
}
},
"KUWH5f1TmYfO1O1wgCJLli3XZFi2" : {
"KUWH5f1TmYfO1O1wgCJLli3XZFi2" : {
"console" : "Steam",
"game" : "Forza 6",
"mic" : "No Mic",
"players" : "2"
}
},
"hpWkq0D8clPReUetOq9Xtmc4V582" : {
"hpWkq0D8clPReUetOq9Xtmc4V582" : {
"console" : "Xbox One",
"game" : "Minecraft",
"mic" : "Mic",
"players" : "4"
},
"players" : "4"
}
},
"users" : {
"8cHrNCybwjO3PIUKxyOLiAqxJBv1" : {
"gamertag" : "thedylan",
"uname" : "thedood"
},
"Cd6lVd2XMUYoLH6b0xoHsrfXMud2" : {
"gamertag" : "dmdylan",
"uname" : "ninja goat"
},
"KUWH5f1TmYfO1O1wgCJLli3XZFi2" : {
"gamertag" : "skaner",
"uname" : "asdf"
},
"YvYEIiCBUSYKTviVyWpLHdyDIFw1" : {
"gamertag" : "joejoe",
"uname" : "Jifflingly"
},
"ZmX9yIZ6MNguQa1S3MaYNcxfK2b2" : {
"gamertag" : "dmkaner",
"uname" : "dmkaner"
},
"hpWkq0D8clPReUetOq9Xtmc4V582" : {
"gamertag" : "dmkaner",
"uname" : "dmkaner"
},
"t21ncnuRmeV4F7RknETBisMrxS42" : {
"gamertag" : "asdf",
"uname" : "asdf"
}
}
}
最佳答案
代码中的问题是您推送数据两次，但没有必要这样做。
"Lobby_Requests" : {
"Cd6lVd2XMUYoLH6b0xoHsrfXMud2" : {
"Cd6lVd2XMUYoLH6b0xoHsrfXMud2" : { //This is wrong
如果您通过仅推送一次数据来更改向 Firebase 数据库添加数据的方式，那么您的代码将正常工作。您的数据库应如下所示:
"Lobby_Requests" : {
"Cd6lVd2XMUYoLH6b0xoHsrfXMud2" : {
"console" : "Xbox One",
"game" : "Forza 6",
"mic" : "Mic",
"players" : "5"
},
正如您可能看到的，只有一个按下的键。
关于java - Android Firebase db datasnapshot 从错误的数据库目录中提取信息，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/45406391/