Android Question basic doubt about accessing and change Map objects

Dim MyMap As Map: MyMap.Initialize
Dim MyElem1 As MyObjType: MyElem1.Initialize
MyElem1.Field1 = "whatever1"
MyElem1.Field2 = "whatever2"
MyMap.Put("key1",MyElem1)

Dim MyElem2 As MyObjType: MyElem2.Initialize
MyElem2.Field1 = "whatever3"
MyElem2.Field2 = "whatever4"
MyMap.Put("key2",MyElem2)

Dim temp As MyObjType = MyMap.Get("key1")
temp.Field1 = "SomethingDifferent"

Dim myOb As MyObjType  = MyMap.Get("key1")
Log(myOb.Field1)

Sub Process_Globals
    Type MyObjType(Field1 As String,Field2 As String)        'Hover over MyObjType
End Sub

Public Sub CreateMyObjType (Field1 As String, Field2 As String) As MyObjType
    Dim t1 As MyObjType
    t1.Initialize
    t1.Field1 = Field1
    t1.Field2 = Field2
    Return t1
End Sub

'Then everything is simplified

    Dim MyMap As Map: MyMap.Initialize
    MyMap.Put("key1", CreateMyObjType ("whatever1", "whatever2"))
    MyMap.Put("key2", CreateMyObjType ("whatever3", "whatever4"))
   
    Dim temp As MyObjType = MyMap.Get("key1")
    temp.Field1 = "SomethingDifferent"
   
    Dim myOb As MyObjType  = MyMap.Get("key1")
    Log(myOb.Field1)

Public Sub UpdateMyObjType (Obj As MyObjType, Field1 As String, Field2 As String)
    If Field1.Length>0 Then Obj.Field1 = Field1
    If Field2.Length>0 Then Obj.Field2 = Field2
End Sub

    Dim MyMap As Map: MyMap.Initialize
    MyMap.Put("key1", CreateMyObjType ("whatever1", "whatever2"))
    MyMap.Put("key2", CreateMyObjType ("whatever3", "whatever4"))
    UpdateMyObjType (MyMap.Get("key1"), "SomethingDifferent", "")