Android Question Keep a Custom List View Item selected

[Mattiaf]

Hi, I have a custom list view and every time I click an item a panel is showing right on top of it. But it would be great to keep the item selected so the user can keep the view on which item he selected. I ve been looking around but it doesn't seem there is a way to keep the item selected, at least, until the panel is displaying right above.. Thanks

 

[mcqueccu]

This is what you are looking for. You can keep single item selected or multiple items

[B4X] CLVSelections - extended selection modes for xCustomListView

This class extends xCustomListView library and adds more selection modes: MODE_SINGLE_ITEM_TEMP - The same as the default behavior. MODE_SINGLE_ITEM_PERMANENT - Single item is selected and the selection remains. MODE_MULTIPLE_ITEMS- Multiple items can be selected. There is also a helper method...

www.b4x.com

 

[Mattiaf]

Thanks.
I added the .bas file as existing module,
on class global

Dim selezionepermanente As CLVSelections

on initialize

selezionepermanente.Initialize(clvChiavi)
    selezionepermanente.Mode = selezionepermanente.MODE_SINGLE_ITEM_PERMANENT

on the cls item click event

selezionepermanente.ItemClicked(Index)

but as soon as I debug, it shows the following error message

Logger connected to:  samsung SM-G985F
--------- beginning of main
*** Service (starter) Create ***
** Service (starter) Start **
** Activity (main) Create, isFirst = true **
Error occurred on line: 35 (CLVSelections)
java.lang.NullPointerException: Attempt to invoke virtual method 'int anywheresoftware.b4a.objects.collections.List.getSize()' on a null object reference
    at b4a.example3.customlistview._getsize(customlistview.java:493)
    at Chiavii.ronda.clvselections._refresh(clvselections.java:251)
    at Chiavii.ronda.clvselections._setmode(clvselections.java:188)
    at Chiavii.ronda.b4xmainpage._initialize(b4xmainpage.java:917)
    at Chiavii.ronda.b4xpagesmanager._initialize(b4xpagesmanager.java:153)
    at Chiavii.ronda.main._activity_create(main.java:420)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:351)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:146)
    at Chiavii.ronda.main.afterFirstLayout(main.java:105)
    at Chiavii.ronda.main.access$000(main.java:17)
    at Chiavii.ronda.main$WaitForLayout.run(main.java:83)
    at android.os.Handler.handleCallback(Handler.java:942)
    at android.os.Handler.dispatchMessage(Handler.java:99)
    at android.os.Looper.loopOnce(Looper.java:226)
    at android.os.Looper.loop(Looper.java:313)
    at android.app.ActivityThread.main(ActivityThread.java:8741)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:571)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1067)
** Activity (main) Resume **

the line 35 in the class is

Public Sub Refresh
    VisibleRangeChanged(0, mCLV.Size - 1)
End Sub

what is the issue? thanks

 

[mcqueccu]

First try and run the example, Understand it before you implement it

 

[Mattiaf]

hmm to be honest I don't see any error between how I implement it and how the b4j example is built... Am I wrong?

 

[Mattiaf]

OK got it..
Just need it on the b4x page created

selezionepermanente.Initialize(clvChiavi)
    selezionepermanente.Mode = selezionepermanente.MODE_SINGLE_ITEM_PERMANENT

 

[Mattiaf]

@mcqueccu just a thing..
How can I parse it as a boolean?
I mean how can i do something like this
if item is clicked then
panel.visible=true
else
item clicked.clear
?