如何檢索已經推送給Firebase中的小孩的最新數據？

因此，我仍然在嘗試使用我的應用程序，並且遇到了另一個磚牆，我想從這組數據中檢索最新的「bloodLevel」，該數據已保存到firebase並將其輸出到textview，我不知道如何我會這樣做：如何檢索已經推送給Firebase中的小孩的最新數據？

"BGRatio" : "1", 
    "CarbRatio" : "5", 
    "Entries" : { 
    "-KfcV3kfCMTcbeSa9Wv6" : { 
     "BloodLevels" : "7.5", 
     "Carbohydrates" : "20", 
     "DateandTime" : "19 Mar 2017, 21:36:47", 
     "Insulin" : "4.5" 
    }, 
    "-KfcX05Fo2XDYLAkrBW-" : { 
     "BloodLevels" : "14", 
     "Carbohydrates" : "65", 
     "DateandTime" : "19 Mar 2017, 21:45:17", 
     "Insulin" : "20.0" 
    }, 
    "-KfcrF6dKSolRl36dn4u" : { 
     "BloodLevels" : "12", 
     "Carbohydrates" : "90", 
     "DateandTime" : "19 Mar 2017, 23:18:03", 
     "Insulin" : "23.0" 
    }, 
    "-Kfeqt1T27RKSNMkZrYA" : { 
     "BloodLevels" : "24", 
     "Carbohydrates" : "10000", 
     "DateandTime" : "20 Mar 2017, 08:35:43", 
     "Insulin" : "2017.0" 
    }, 
    "-Kg4DU0eM8sx9uIHbDL4" : { 
     "BloodLevels" : "13.3", 
     "Carbohydrates" : "50", 
     "DateandTime" : "Mar 25, 2017, 11:28:54 AM", 
     "Insulin" : "16.3" 
    }, 
    "-KgIxNJNSDpTAKpo62hn" : { 
     "BloodLevels" : "8.0", 
     "Carbohydrates" : "40", 
     "DateandTime" : "Mar 28, 2017, 9:08:30 AM", 
     "Insulin" : "9.0" 
    }, 
    "-KgOJ-4eGU5z_dTuxfoq" : { 
     "BloodLevels" : "10", 
     "Carbohydrates" : "50", 
     "DateandTime" : "Mar 29, 2017, 10:05:25 AM", 
     "Insulin" : "13.0" 
    } 
    }, 
    "Ideal Level" : "7" 
}

任何幫助，這將是偉大的，謝謝你！

來源

2017-04-07 Kenan Jasim