questionare in android app by firebase (json)

export.json

{
  "user_feedback" : {
    "-KVDxmeEV90ikzTrqvcO" : {
      "feedbackDetail" : "ลองแปป",
      "feedbackTopic" : "เทส",
      "feedbackType" : "App problem",
      "timestamp" : "29/10/2016 12:43:49",
      "email" : "[email protected]"
    },
    "-KVDzbD9Ct0K5sAYJ7V9" : {
      "feedbackDetail" : "องๆ",
      "feedbackTopic" : "ลองอีก",
      "feedbackType" : "User feedback",
      "timestamp" : "29/10/2016 12:51:46",
      "email" : "[email protected]"
    } 
}