Android Question delete some items from list

PassionDEV

Active Member
Licensed User
i have the followig list and i want to delete the whole list and leave the last 4 items was inserted in the list based on some condition , is it possible ?

B4X:
dim Type cmdline(command as string)
dim CommandList As List

if CommandList.Size  > 50 then

For i = 0 To CommandList.Size - 1
Dim cmd As cmdline
cmd = CommandList.Get(i)
'here i want to delete all items that contain something and leave the last 4 items inserted how can i possibly do that ?
If cmd.command = "something" Then
CommandList.RemoveAt(i)
End If


Next

End if
 

OliverA

Expert
Licensed User
Not a solution, just a tip. You need to start from the top of the list and work down when you are removing items from the list, otherwise you will not get the results you want.
 

PassionDEV

Active Member
Licensed User
i have started the loop from top but i am not sure on how to skip the last 4 items in the list while removing

B4X:
if CommandList.Size  > 50 then

For i =  CommandList.Size -1 To 0 Step -1
Dim cmd As cmdline
cmd = CommandList.Get(i)
If cmd.command = "something" Then
CommandList.RemoveAt(i)
End If


Next

End if
 

DonManfred

Expert
Licensed User
PUT ON your brain! It is simple MATH.

For i = CommandList.Size -1 To 0 Step -1
CommandList.Size -1 is the last item.
CommandList.Size -1-4 is 4 items less then the last.

B4X:
For i =  CommandList.Size -5 To 0 Step -1
 

PassionDEV

Active Member
Licensed User
i was asking about the last 4 items that equal to same condition "something" because this list will have multiable items with a different commands name skipping the last 4 items in the total list will remove the last 4 items if they equal the condition "something" but what if the last 4 items are mixed with different names

i think i should calculate each loop with a global integer and count each "something" condition in order to target those conditions only i know that i should set size- if i want to skip this order in list i got misunderstood
 

DonManfred

Expert
Licensed User
Untested but i think it should bring your the in the right direction!?

B4X:
    If CommandList.Size  > 50 Then
        Dim toRemove As List
        toRemove.Initialize
        For i =  CommandList.Size -1 To 0 Step -1
            Dim cmd As cmdline
            cmd = CommandList.Get(i)
            If cmd.command = "something" Then
                'CommandList.RemoveAt(i)
                toRemove.Add(i)
            End If
        Next
        '
        If toRemove.Size>4 Then
            For i = toRemove.Size -5 To 0 Step -1
                CommandList.RemoveAt(toRemove.Get(i))
            Next
        End If
    End If
 

emexes

Well-Known Member
Licensed User
B4X:
'here i want to delete all items that contain something and leave the last 4 items inserted how can i possibly do that ?
Do While CommandList.Size > 4
    CommandList.RemoveAt(0)
Loop
 

OliverA

Expert
Licensed User
If your list items are
1,9,2,9,3,9,4,9,5,9,9,9,9
And the item 9 is what you are looking for, then should the end result be
1,2,3,4,5,9,9,9,9
Or
1,9,2,9,3,9,4,9,5
Or
9,9,9,9 and it is all the 9’s before the 5
Or
9,9,9,9 and it is all the 9’s after the 5
 
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