Android Question map assignment question

Multiverse app · Mar 19, 2019

I have a simple question.

B4X:

    Dim mapGlobal As Map
    mapGlobal.Initialize
    mapGlobal.Put("Key1", "Value1")
    map2=mapGlobal

Does the "=" the pass the reference of the mapGlobal to map2 or creates an object at new memory location?

RB Smissaert · Mar 19, 2019

Multiverse app said:
I have a simple question.

B4X:

Dim mapGlobal As Map mapGlobal.Initialize mapGlobal.Put("Key1", "Value1") map2=mapGlobal

Does the "=" the pass the reference of the mapGlobal to map2 or creates an object at new memory location?

Can't test it now, but how about altering mapGlobal and see if that change shows in map2?

RBS

Multiverse app · Mar 19, 2019

RB Smissaert said:
Can't test it now, but how about altering mapGlobal and see if that change shows in map2?

Yes, it does

B4X:

    Dim mapGlobal As Map
    mapGlobal.Initialize
    mapGlobal.Put("Key1", "Value1")
    mapGlobal.Put("Key2", "Value2")
    mapGlobal.Put("Key3", "Value3")
    mapGlobal.Put("Key4", "Value4")
   
   
    Dim map2 As Map=mapGlobal
    Log(map2.Remove("Key1"))
   
    Log("mapGlobal: ")
    For i=0 To mapGlobal.Size-1
        Log(mapGlobal.GetKeyAt(i)&", "&mapGlobal.GetValueAt(i))
    Next
   
    Log("map2: ")
    For i=0 To map2.Size-1
        Log(map2.GetKeyAt(i)&", "&map2.GetValueAt(i))
    Next

log:

B4X:

Value1
mapGlobal: 
Key2, Value2
Key3, Value3
Key4, Value4
map2: 
Key2, Value2
Key3, Value3
Key4, Value4

Erel · Mar 19, 2019

1. You should never use GetKeyAt / GetValueAt.

B4X:

For Each Key As String In map2.Keys
 Log($"${Key}: ${map2.Get(Key)}"$)
Next

2. You can use CreateMap:

B4X:

Dim MyGlobal As Map = CreateMap("Key1": "Value1", "Key2": "Value2")

Android Question map assignment question

Multiverse app

Active Member

RB Smissaert

Well-Known Member

Multiverse app

Active Member

Erel

B4X founder

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Android Question map assignment question

Multiverse app

Active Member

RB Smissaert

Well-Known Member

Multiverse app

Active Member

Erel

B4X founder

Similar Threads

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