Firebase數據庫獲取數據？

Question

我是Firebase新手，我的問題是如何從Firebase獲取數據，下圖顯示了我的數據庫的詳細信息。

我想從user_time_table中獲取數據，那個UID在每個uid裏面都有saven天，每天都顯示有時間和槽在那裏我想要在listView中獲取這些拖拽數據，並像在下面的圖片

我怎麼也來從火力地堡的時間？

object class 





public String uid; 
    public String username; 
    public String address; 
    public String day; 
    public String slot; 
    public long time; 
    public int starCount = 0; 
    public Map<String, Boolean> stars = new HashMap<>(); 

    public drPost() { 
     // Default constructor required for calls to DataSnapshot.getValue(Post.class) 
    } 



    public drPost(String uid, String username, String address, String day, String slot, long time) { 
     this.uid = uid; 
     this.username = username; 
     this.address = address; 
     this.day = day; 
     this.slot = slot; 
     this.time = time; 
    } 

    // [START post_to_map] 
    @Exclude 
    public Map<String, Object> toMap() { 
     HashMap<String, Object> result = new HashMap<>(); 
     result.put("uid", uid); 
     result.put("address", address); 
     result.put("day", day); 
     result.put("slot", slot); 
     result.put("time", time); 
     result.put("starCount", starCount); 
     result.put("stars", stars); 

     return result; 
    } 
    // [END post_to_map] 
    public long getTime() { 
     return time; 
    } 

    public String getSlot(){ 
     return slot; 
    } 


    public String getDay(){ 
     return day; 
    } 



} 

// [END post_class]

///獲取並查看///

enter code here 


public class timetable extends Activity { 
    ListView listView, listView2; 
    List<drPost> drpostList = new ArrayList<>(); 
    // DatabaseReference databasetimeandslot; 
    DatabaseReference databaseReference; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_timetable); 


     databaseReference = FirebaseDatabase.getInstance().getReference().child("user_time_table").child("userID"); 

     // Get ListView object from xml 
     listView = (ListView) findViewById(R.id.list1); 

     listView2 = (ListView) findViewById(R.id.list1); 

     drpostList = new ArrayList<>(); 

     // Defined Array values to show in ListView 
     String[] values = new String[]{ 
       "Monday", 
       "Tuesday", 
       "Wednesday", 
       "Thursday", 
       "Friday", 
       "Saturday", 
       "Sunday" 

     }; 

     // Define a new Adapter 
     // First parameter - Context 
     // Second parameter - Layout for the row 
     // Third parameter - ID of the TextView to which the data is written 
     // Forth - the Array of data 

     ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, 
       R.layout.timetable_items, R.id.type, values); 


     // Assign adapter to ListView 
     listView.setAdapter(adapter); 

     // ListView Item Click Listener 
     listView.setOnItemClickListener(new AdapterView.OnItemClickListener() { 

      @Override 
      public void onItemClick(AdapterView<?> parent, View view, 
            int position, long id) { 


       // ListView Clicked item index 
       int itemPosition = position; 

       // ListView Clicked item value 
       String itemValue = (String) listView.getItemAtPosition(position); 

       Intent intent = new Intent(timetable.this, EditTimeTable.class); 
       intent.putExtra("key", itemValue); 
       startActivity(intent); 

       // Show Alert 
       Toast.makeText(getApplicationContext(), "" + itemValue, Toast.LENGTH_LONG).show(); 

      } 

     }); 
    } 




     @Override 
     protected void onStart() { 
      super.onStart(); 


      databaseReference.addValueEventListener(new ValueEventListener() { 
       @Override 
       public void onDataChange(DataSnapshot dataSnapshot) { 

        //clearing the previous artist list 
        drpostList.clear(); 

        //iterating through all the nodes 
        for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) { 
         //getting artist 
         drPost drpost = postSnapshot.getValue(drPost.class); 
         //adding artist to the list 
         drpostList.add(drpost); 
        } 

        //creating adapter 
        timeandslot artistAdapter = new timeandslot(timetable.this, drpostList); 
        //attaching adapter to the listview 
        listView2.setAdapter(artistAdapter); 
       } 

       @Override 
       public void onCancelled(DatabaseError databaseError) { 

       } 
      }); 


     } 
    } 


enter code here 







    public class timeandslot extends ArrayAdapter<drPost> { 
     private Activity context; 
     List<drPost> drpost; 

     public timeandslot(Activity context, List<drPost> drpost) { 
      super(context, R.layout.timetable_items, drpost); 
      this.context = context; 
      this.drpost = drpost; 
     } 
    @Override 
    public View getView(int position, View convertView, ViewGroup parent) { 
     LayoutInflater inflater = context.getLayoutInflater(); 
     View listViewItem = inflater.inflate(R.layout.timetable_items, null, true); 

     // TextView version_TIME = (TextView) listViewItem.findViewById(R.id.version_TIME); 
     TextView version_SLOT = (TextView) listViewItem.findViewById(R.id.version_SLOT); 
     TextView Day = (TextView) listViewItem.findViewById(R.id.type); 

     drPost drposts = drpost.get(position); 
    // version_TIME.setText((int) drposts.getTime()); 
     version_SLOT.setText(drposts.getSlot()); 
     Day.setText(drposts.getDay()); 

     return listViewItem; 
    } 
} 

Answer 1

DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference(). 
       child("user_timetable"); 

databaseReference.child("uid").addChildEventListner(new ChildEventListener() 

    enter code here 

{ 

      @Override 
      public void onChildAdded(DataSnapshot dataSnapshot, String s) { 
       if (dataSnapshot != null && dataSnapshot.getValue() != null) 
        ObjectModel chat = dataSnapshot.getValue(ObjectModel.class); 
      } 

      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) { 

      } 
     });