有人可以讓我知道這段代碼有什麼問題嗎？

Question

我想能夠複製uid（圖中藍色下劃線），並將其與當前用戶的uid進行比較。而且，只有在同一個uid下沒有數據時才寫入數據庫。這是爲了讓每個用戶只上傳一次數據。

Link to database screenshot

buttonSubmit.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View view) { 
       if(mDatabaseReference.child("drivers").child(userid).toString() != userid || mDatabaseReference.child("parents").child(userid).toString() != userid){ 
        if (!radiobutton1.isChecked() && !radiobutton2.isChecked()) { 
         Toast.makeText(LoggedinActivity.this, "Please select either Driver or Parent", Toast.LENGTH_LONG).show(); 
        } else if (radiogroup.getCheckedRadioButtonId() == radiobutton1.getId()) { 
         typestring = "driver"; 
         Users users = new Users(useremail, editText.getText().toString(), typestring); 
         mDatabaseReference.child("drivers").child(userid).setValue(users); 
        } else if (radiogroup.getCheckedRadioButtonId() == radiobutton2.getId()) { 
         typestring = "parent"; 
         Users users = new Users(useremail, editText.getText().toString(), typestring); 
         mDatabaseReference.child("parents").child(userid).setValue(users); 
        } 
       }else if(mDatabaseReference.child("drivers").child(userid).toString() == userid || mDatabaseReference.child("parents").child(userid).toString() == userid){ 
        Toast.makeText(LoggedinActivity.this, "User info already submitted", Toast.LENGTH_LONG).show(); 
       } 
      } 
     }); 

Answer 1

你做錯了。查看文檔以查看如何從數據庫檢索值。 https://firebase.google.com/docs/database/admin/retrieve-data#value