Firebase检索所有子值并显示

Question

Firebase android：如何检索所有用户联系人并使用recyclerview向他们显示？请帮帮我。预先谢谢你。

my database screenshot

Answer 1

根据您的数据库结构

您的数据库结构有点破损，但是您可以尝试

Users = FirebaseDatabase.getInstance().getReference("users");
Contacts = FirebaseDatabase.getInstance().getReference("users");

Users.addValueEventListener(new ValueEventListener() {
      @Override
      public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
          for(DataSnapshot userKeys:dataSnapshot.getChildren()){
              //get All the users
              final String users = userKeys.getKey();
              //get contacts
              Contacts.child(users).child("contact").addValueEventListener(new ValueEventListener() {
                  @Override
                  public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                      for(DataSnapshot contacts:dataSnapshot.getChildren()){
                          String contact = contacts.getValue(String.class);
                          Toast.makeText(getApplicationContext(),contact+"of"+users,Toast.LENGTH_SHORT).show();
                      }
                  }

                  @Override
                  public void onCancelled(@NonNull DatabaseError databaseError) {

                  }
              });
              //end of get contact
          }
          //End of for each
      }

      @Override
      public void onCancelled(@NonNull DatabaseError databaseError) {

      }
  });