B4J Question Maps - order of elements

LucaMs · Jun 14, 2016

Erel said:
Note that in most implementations of maps the order is not preserved. In most use cases the order is not important.
The order in B4A and B4J maps is preserved. This is not the case in B4i.
B4A and B4J Maps include two methods named GetValueAt and GetKeyAt. These methods are only available because of historic reasons (before the For Each block was available). You shouldn't use these methods.

If: "The order in B4A and B4J maps is preserved."
why: You shouldn't use these methods (GetValueAt and GetKeyAt)?

Also, can I... safely use the class you (Erel) posted here with B4J "thread safe maps"?

Thank you

Erel · Jun 14, 2016

LucaMs said:
why: You shouldn't use these methods (GetValueAt and GetKeyAt)?

These methods were introduced before the For Each loop was available as a way to iterate over the entries.
There performance can be bad if they are misused.

The correct and simple way to iterate over a Map is with a For Each loop.

LucaMs said:
Also, can I... safely use the class you (Erel) posted here with B4J "thread safe maps"?

No. Or more correctly only if you add locks in all the methods. In that case you should use a regular Map anyway.

LucaMs · Jun 14, 2016

Thank you, Erel

B4J Question Maps - order of elements

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