java-如何遍历Android中的Firebase结构？

概述我需要遍历Firebase架构以获取每次锻炼的数据.在RecyclerView中显示它.现在,我无法使用侦听器&在Firebase中遍历该模式.通过称为程序的POJO类获取它.Firebase的JSON{"subscriptions":{"han@gmail,com":{"-KDnhRwHjssOejrqyenP":{"category":&qu

我需要遍历Firebase架构以获取每次锻炼的数据.在RecyclerVIEw中显示它.
现在,我无法使用侦听器&在Firebase中遍历该模式.通过称为程序的POJO类获取它.

Firebase的JSON

{  "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" ]        }      }    }  }  }

侦听器代码

    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());                }            });        }

logcat的

03-28 08:52:53.966 23584-23584/com.androID.sam I/System.out: {-KDni3TN4NMyGXePyp92={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]}, Title=Indian Workouts, category=Strength, length=1, goal=This workout can be done by a BABUJI}, -KDnhRwHJssOejrqyenP={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]}, Title=Hello Workouts, category=Strength, length=1, goal=This workout can be done while on the phone!}}

03-28 08:52:53.967 23584-23584/com.androID.sam I/System.out: {-KDnfjROKeFAL9wccsxY={weeks={week1=[High Knees, Squats, Lunges, Diamond Push-ups, Lying Triceps lifts]}, Title=Afternoon HiiT, category=mobility, length=1, goal=afternoon body weight workout}, -KDps90Dn6XtJc6Co00b={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]}, Title=Title, category=Strength, length=1, goal=goal}}

Program.java

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;    }    }

解决方法:

正如@ReazMurshed所说的,您快到了.但是您无法在树中迭代一个级别.似乎ref指向JsON中的subscriptions节点.在此之下,您拥有用户,然后有了推送ID.因此,您需要执行一个双循环：

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) {  }});

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