B4J Question How to filter objects ?

[FrenchDeveloper]

Hello,
I have a set of objects. Each object is an imageview + properties.
This set will grow without limit.
What is the best solution to filter these objects upon one property ?

For example :

Object1 Imageview1 Group1
Object2 Imageview2 Group1
Object3 Imageview3 Group1
Object4 Imageview4 Group2
Object5 Imageview5 Group2

I need to do something on all imageviews of group2.
I could scan each object with a For Each loop but it may be quite long with a lot of objects.
I could copy all properties in a database, a table or in a map and filter the database, the table or the map. Is it possible to filter a table or a map ?
What is the most efficient solution ?

 

[stevel05]

You could keep an index (as a Map) of the objects that contain each group keyed on the group with a list of objects as the Value.

 

[Daestrum]

You could store the info you want using setUserData in each Imageview, then retrieve it with getUserData. It takes a java object so you could store almost anything in there.
You would probably need to use RunMethod to access the field as I don't think B4J exposes it.

 

[FrenchDeveloper]

You could keep an index (as a Map) of the objects that contain each group keyed on the group with a list of objects as the Value.

Thank you for your answer!
As I am a newbie, I don't imagine how the code would be and how to filter a map upon this index. May be you know a thread where I can find example ?

 

[FrenchDeveloper]

You could store the info you want using setUserData in each Imageview, then retrieve it with getUserData. It takes a java object so you could store almost anything in there.
You would probably need to use RunMethod to access the field as I don't think B4J exposes it.

Thanks for this advice ! I didn't think it would be possible to store informations in java objects.
How to filter upon one of these informations ?

 

[stevel05]

If you can give me an example of how you are coding the structure, I'll give you an example of indexing it using Map.

 

[FrenchDeveloper]

If you can give me an example of how you are coding the structure, I'll give you an example of indexing it using Map.

Thank you very much Stevel ! I added a project in the first post.
May be you know where I can find further informations on maps purpose and coding ?

 

[stevel05]

No Problem, attached is an example.

You can get info on maps from the internet, there are many examlples. One is: http://www.javamex.com/tutorials/collections/using_4.shtml.

Although the examples will be in java, it should be easy to change for B4a/j. If you get any questions just post then in the forums and someone will help.

Steve

 

[stevel05]

Maps have many uses, in the example above it is used to keep a keyed index, in the example here: http://www.b4x.com/android/forum/threads/running-totals-with-a-map.39324/

it is used to keep running totals.

 

[FrenchDeveloper]

Thanks a lot !