Android firebase查询多个子

大家好，我正在尝试选择包含特定姓名学生的课程，这可能是因为有多个学生注册了一门课程，但我仍然无法解决这个问题。（非常类似的查询，例如，对于课程名称的查询工作得非常好）数据快照看起来像{key:course，value:null}，即使存在应该满足条件的课程

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}

如果您可以将数据结构发布为文本而不是屏幕截图，这会很有帮助。只需从Firebase控制台将数据导出为JSON文件，并将其添加到您的问题中。检查我对这个问题的回答

   Query query= mDatabase.child("courses").orderByChild("students/name").equalTo("Dominik Skoczylas");
    query.addValueEventListener(new ValueEventListener() {
        @Override

        public void onDataChange(DataSnapshot dataSnapshot) {
            if (dataSnapshot.exists()) {
                for (DataSnapshot child : dataSnapshot.getChildren())

                {
                    userCourse = child.getValue(Course.class);

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

        }
    });




  "courses" : {
"-Kfo-G37vwtUkWAv1zE_" : {
  "modules" : [ {
    "lectures" : [ {
      "endTime" : {
        "date" : 1,
        "day" : 4,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1517446861000,
        "timezoneOffset" : 0,
        "year" : 118
      },
      "room" : {
        "name" : "J100"
      },
      "starTime" : {
        "date" : 1,
        "day" : 3,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1485910861000,
        "timezoneOffset" : 0,
        "year" : 117
      },
      "topic" : "Distributed 1"
    }, {
      "endTime" : {
        "date" : 1,
        "day" : 4,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1517446861000,
        "timezoneOffset" : 0,
        "year" : 118
      },
      "room" : {
        "name" : "J200"
      },
      "starTime" : {
        "date" : 1,
        "day" : 3,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1485910861000,
        "timezoneOffset" : 0,
        "year" : 117
      },
      "topic" : "Distributed 2"
    } ],
    "name" : "Distributed computing"
  }, {
    "lectures" : [ {
      "endTime" : {
        "date" : 1,
        "day" : 4,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1517446861000,
        "timezoneOffset" : 0,
        "year" : 118
      },
      "room" : {
        "name" : "J100"
      },
      "starTime" : {
        "date" : 1,
        "day" : 3,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1485910861000,
        "timezoneOffset" : 0,
        "year" : 117
      },
      "topic" : "Advanced 1"
    }, {
      "endTime" : {
        "date" : 1,
        "day" : 4,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1517446861000,
        "timezoneOffset" : 0,
        "year" : 118
      },
      "room" : {
        "name" : "J200"
      },
      "starTime" : {
        "date" : 1,
        "day" : 3,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1485910861000,
        "timezoneOffset" : 0,
        "year" : 117
      },
      "topic" : "Advanced 2"
    } ],
    "name" : "Advanced internet"
  }, {
    "lectures" : [ {
      "endTime" : {
        "date" : 1,
        "day" : 4,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1517446861000,
        "timezoneOffset" : 0,
        "year" : 118
      },
      "room" : {
        "name" : "J100"
      },
      "starTime" : {
        "date" : 1,
        "day" : 3,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1485910861000,
        "timezoneOffset" : 0,
        "year" : 117
      },
      "topic" : "Concurrent 1"
    }, {
      "endTime" : {
        "date" : 1,
        "day" : 4,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1517446861000,
        "timezoneOffset" : 0,
        "year" : 118
      },
      "room" : {
        "name" : "J200"
      },
      "starTime" : {
        "date" : 1,
        "day" : 3,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1485910861000,
        "timezoneOffset" : 0,
        "year" : 117
      },
      "topic" : "Concurrent 2"
    } ],
    "name" : "Concurrent programming"
  } ],
  "name" : "Software Engineering",
  "students" : [ {
    "name" : "Dominik Skoczylas"
  }, {
    "name" : "Marta Mleczko"
  }, {
    "name" : "Zenon Zenon"
  }, {
    "name" : "Matt Damon"
  } ]
},
"-Kfo-G3G4ndKYpKHhtgV" : {
  "modules" : [ {
    "lectures" : [ {
      "endTime" : {
        "date" : 1,
        "day" : 4,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1517446861000,
        "timezoneOffset" : 0,
        "year" : 118
      },
      "room" : {
        "name" : "J100"
      },
      "starTime" : {
        "date" : 1,
        "day" : 3,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1485910861000,
        "timezoneOffset" : 0,
        "year" : 117
      },
      "topic" : "Concurrent 1"
    }, {
      "endTime" : {
        "date" : 1,
        "day" : 4,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1517446861000,
        "timezoneOffset" : 0,
        "year" : 118
      },
      "room" : {
        "name" : "J200"
      },
      "starTime" : {
        "date" : 1,
        "day" : 3,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1485910861000,
        "timezoneOffset" : 0,
        "year" : 117
      },
      "topic" : "Concurrent 2"
    } ],
    "name" : "Concurrent programming"
  }, {
    "lectures" : [ {
      "endTime" : {
        "date" : 1,
        "day" : 4,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1517446861000,
        "timezoneOffset" : 0,
        "year" : 118
      },
      "room" : {
        "name" : "J100"
      },
      "starTime" : {
        "date" : 1,
        "day" : 3,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1485910861000,
        "timezoneOffset" : 0,
        "year" : 117
      },
      "topic" : "Graphics 1"
    }, {
      "endTime" : {
        "date" : 1,
        "day" : 4,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1517446861000,
        "timezoneOffset" : 0,
        "year" : 118
      },
      "room" : {
        "name" : "J200"
      },
      "starTime" : {
        "date" : 1,
        "day" : 3,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1485910861000,
        "timezoneOffset" : 0,
        "year" : 117
      },
      "topic" : "Graphics 2"
    } ],
    "name" : "Graphics"
  }, {
    "lectures" : [ {
      "endTime" : {
        "date" : 1,
        "day" : 4,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1517446861000,
        "timezoneOffset" : 0,
        "year" : 118
      },
      "room" : {
        "name" : "J100"
      },
      "starTime" : {
        "date" : 1,
        "day" : 3,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1485910861000,
        "timezoneOffset" : 0,
        "year" : 117
      },
      "topic" : "Artificial 1"
    }, {
      "endTime" : {
        "date" : 1,
        "day" : 4,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1517446861000,
        "timezoneOffset" : 0,
        "year" : 118
      },
      "room" : {
        "name" : "J200"
      },
      "starTime" : {
        "date" : 1,
        "day" : 3,
        "hours" : 1,
        "minutes" : 1,
        "month" : 1,
        "seconds" : 1,
        "time" : 1485910861000,
        "timezoneOffset" : 0,
        "year" : 117
      },
      "topic" : "Artificial 2"
    } ],
    "name" : "Artificial intelligence"
  } ],
  "name" : "Computer Science",
  "students" : [ {
    "name" : "Leonardo Dicaprio"
  }, {
    "name" : "John Lennon"
  }, {
    "name" : "Anthony Bond"
  }, {
    "name" : "Andy Jones"
  } ]
}