Java 如何在Android中遍历Firebase结构？
我需要遍历Firebase模式以获取每个Java 如何在Android中遍历Firebase结构？,java,android,firebase,firebase-realtime-database,Java,Android,Firebase,Firebase Realtime Database,我需要遍历Firebase模式以获取每个训练的数据&将其显示在RecyclerView中。 现在我无法使用侦听器遍历Firebase中的模式&通过名为Program的POJO类获取它 来自Firebase的JSON { "subscriptions" : { "han@gmail,com" : { "-KDnhRwHjssOejrqyenP" : { "category" :
训练的数据Program{
"subscriptions" : {
"han@gmail,com" : {
"-KDnhRwHjssOejrqyenP" : {
"category" : "Strength",
"goal" : "This workout can be done while on the phone!",
"length" : 1,
"title" : "Hello Workouts",
"weeks" : {
"week1" : [ "High Knees", "Jumping Jacks", "Wall sit", "Pushups", "Sit-ups", "Step ups", "Squats", "Tricep dips on chair", "Plank", "High Knees running in place", "Lunges", "Pushup and rotation", "Side plank (alternate per round)", "Alternating Push-Up Plank", "Chest Expander", "Diamond Push-ups", "Dive Bomber Push-ups", "Butt Kickers", "Lying Triceps Lifts", "One Arm Side Push-up", "Overhead Arm Clap", "Overhead Press", "Power Circles", "Push-up and Rotation", "T Push-ups", "Reverse Plank", "Spiderman Push-up", "T Raise", "Tricep Dips", "Wall Push-ups", "Wide Arm Push-ups", "Burpees" ]
}
},
"-KDni3TN4NMyGXePyp92" : {
"category" : "Strength",
"goal" : "This workout can be done by a BABUJI",
"length" : 1,
"title" : "Indian Workouts",
"weeks" : {
"week1" : [ "Diamond Pushups", "Jackknives", "Plyo Lunges", "Plyo Squats", "Single leg plank (alternate per round)", "Plyo Lunges", "Pushup and rotation", "Weighted side plank (alternate per round)", "Alternating Push-Up Plank", "Chest Expander", "Diamond Push-ups", "Dive Bomber Push-ups", "One Arm Side Push-up", "Overhead Press", "Push-up and Rotation", "T Push-ups", "Spiderman Push-up", "Wide Arm Push-ups", "Burpee Pushups" ]
}
}
},
"obama@gmsil,com" : {
"-KDnfjROKeFAL9wccsxY" : {
"category" : "Mobility",
"goal" : "afternoon body weight workout",
"length" : 1,
"title" : "Afternoon HiiT",
"weeks" : {
"week1" : [ "High Knees", "Squats", "Lunges", "Diamond Push-ups", "Lying Triceps Lifts" ]
}
},
"-KDps90Dn6XtJc6Co00b" : {
"category" : "Strength",
"goal" : "goal",
"length" : 1,
"title" : "title",
"weeks" : {
"week1" : [ "Diamond Pushups", "Jackknives", "Plyo Lunges", "Plyo Squats", "Single leg plank (alternate per round)", "Plyo Lunges", "Pushup and rotation", "Weighted side plank (alternate per round)", "Alternating Push-Up Plank", "Chest Expander", "Diamond Push-ups", "Dive Bomber Push-ups", "One Arm Side Push-up", "Overhead Press", "Push-up and Rotation", "T Push-ups", "Spiderman Push-up", "Wide Arm Push-ups", "Burpee Pushups" ]
}
}
}
}
}
public void FB(){
ref.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot snapshot) {
for (DataSnapshot postSnapshot: snapshot.getChildren()) {
System.out.println(postSnapshot.getValue());
//Program post = proSnapshot.getValue(Program.class);
}
}
@Override
public void onCancelled(FirebaseError firebaseError) {
System.out.println("The read failed: " + firebaseError.getMessage());
}
});
}
public class Program {
private String title;
private String goal;
private String category;
private int length;
HashMap<String, ArrayList<String>> weeks;
/**
* Required public constructor
*/
public Program() {
}
public Program(String title, String goal, String category, int length, HashMap<String, ArrayList<String>> weeks) {
this.title = title;
this.goal = goal;
this.category = category;
this.length = length;
this.weeks = weeks;
}
public String getTitle() {
return title;
}
public String getGoal() {
return goal;
}
public String getCategory() {
return category;
}
public int getLength() {
return length;
}
public HashMap<String, ArrayList<String>> getweeks() {
return weeks;
}
}
公共类程序{
私有字符串标题；
私有字符串目标；
私有字符串类别；
私有整数长度；
HashMap周；
/**
*必需的公共构造函数
*/
公共计划（）{
}
公共程序（字符串标题、字符串目标、字符串类别、整数长度、HashMap周）{
this.title=标题；
这个。目标=目标；
this.category=类别；
这个长度=长度；
本周=周；
}
公共字符串getTitle（）{
返回标题；
}
公共字符串getGoal（）{
回归目标；
}
公共字符串getCategory（）{
退货类别；
}
公共整数getLength（）{
返回长度；
}
公共HashMap getweeks（）{
返回周；
}
}
addListenerForSingleValueEventProgramListpublic class ProgramList {
public List<Program> mProgramList;
}
您可能会再次检查android中的数据检索。使用与此处相同的数据库结构。您就快到了。您只需使用引用添加
addListenerForSingleValueEventProgramListpublic class ProgramList {
public List<Program> mProgramList;
}
您可能会再次检查android中的数据检索。使用与此处相同的数据库结构。正如@ReazMurshed所说，您就快到了。但是您没有在树中的一个级别上进行迭代。似乎ref指向JSON中的
订阅节点。在该节点下，您有用户，然后您有e推送ID。因此您需要执行双循环：
ref.addListenerForSingleValueEvent(new ValueEventListener) {
public void onDataChange(DataSnapshot snapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot userSnapshot : snapshot.getChildren()) {
for (DataSnapshot programSnapshot : userSnapshot.getChildren()) {
Program program = programSnapshot.getValue(Program.class);
}
}
}
public void onCancelled(FirebaseError firebaseError) {
}
});
正如@ReazMurshed所说，您就快到了。但是您无法在树中的一个级别上进行迭代。似乎ref指向JSON中的订阅节点。在该节点下，您有用户，然后有推送ID。因此，您需要进行双循环：
ref.addListenerForSingleValueEvent(new ValueEventListener) {
public void onDataChange(DataSnapshot snapshot) {
if (dataSnapshot.exists()) {
for (DataSnapshot userSnapshot : snapshot.getChildren()) {
for (DataSnapshot programSnapshot : userSnapshot.getChildren()) {
Program program = programSnapshot.getValue(Program.class);
}
}
}
public void onCancelled(FirebaseError firebaseError) {
}
});
问题出在哪里？您是否尝试过进行任何映射？我有一个名为Program的POJO类来进行映射。但是我无法遍历并获取Push ID中的数据？我猜这将是DataSnapshot.forEach（）的情况
，但仍然很不清楚。程序
类映射到JSON中的哪个节点？程序
类看起来像什么（将您已经拥有的添加到问题中）？@FrankvanPuffelen每个训练都映射到程序POJO。将POJO添加到问题中！问题出在哪里？您是否尝试进行任何映射？我有一个名为Program的POJO类来进行映射。但是我无法遍历并获取Push ID中的数据？我猜这将是一个DataSnapshot.forEach（）的情况
，但仍然很不清楚。程序
类映射到JSON中的哪个节点？程序
类看起来像什么（将您已经拥有的添加到问题中）？@FrankvanPuffelen每个训练都映射到程序POJO。将POJO添加到问题中！它不起作用，因为我们必须在推ID之后遍历。这样它才能从那里获取数据。目前，它在快照中包含推ID。因此它返回“未能跳转到类型”异常！未能跳转到类型表示您的程序POJO与您在Firebase数据库中使用的程序不同。请删除