List UnsupportedOperationException

[warwound]

Is it a bug or not:

Sub Process_Globals

End Sub

Sub Globals

End Sub

Sub Activity_Create(FirstTime As Boolean)
   Dim MyList As List
   MyList.Initialize2(Array As Int(1, 20, 14, 9))
   MyList.Clear
End Sub

Sub Activity_Resume

End Sub

Sub Activity_Pause (UserClosed As Boolean)

End Sub

** Activity (main) Create, isFirst = true **
main_activity_create (java line: 233)
java.lang.UnsupportedOperationException
at java.util.AbstractList.remove(AbstractList.java:645)
at java.util.AbstractList$SimpleListIterator.remove(AbstractList.java:77)
at java.util.AbstractList.removeRange(AbstractList.java:665)
at java.util.AbstractList.clear(AbstractList.java:473)
at anywheresoftware.b4a.objects.collections.List.Clear(List.java:68)
at b4a.example.main._activity_create(main.java:233)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:165)
at b4a.example.main.afterFirstLayout(main.java:84)
at b4a.example.main.access$100(main.java:16)
at b4a.example.main$WaitForLayout.run(main.java:72)
at android.os.Handler.handleCallback(Handler.java:587)
at android.os.Handler.dispatchMessage(Handler.java:92)
at android.os.Looper.loop(Looper.java:130)
at android.app.ActivityThread.main(ActivityThread.java:3835)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:507)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:858)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
at dalvik.system.NativeStart.main(Native Method)
java.lang.UnsupportedOperationException

This has been reported before: http://www.b4x.com/forum/basic4andr...sic4android-v2-00-released-10.html#post111542

And is related to the problem i posted about here: http://www.b4x.com/forum/libraries-...71-passing-b4a-list-arraylist.html#post135851

A List created with the Initialize2 method does not have the same behaviour or type as a list created with the Initialize method.

Martin.

 

[Erel]

See List.Initialize2 documentation:
Basic4android Search: list.initialize2

This method wraps an existing array and allows you to pass it to methods that expect a list instead of an array. (Usually it is not required as the compiler will wrap arrays automatically.)

 

[warwound]

Ok.

So it's not really a bug as such, more of a limitation that applies to a List created from an Array using Initialize2 method.

Martin.

 

[murdoch1976]

I'm getting the same error, however for me it's when I use the "RemoveAt" method.

I too have used initialize2 to initialise the control...

lstImages.Initialize2(File.ListFiles(pthRoot & "/" & pthIMG))

... is there any way of removing items from this list without tripping this exception?

java.lang.UnsupportedOperationException
at java.util.AbstractList.remove(AbstractList.java:638)
at anywheresoftware.b4a.objects.collections.List.RemoveAt(List.java:95)

 

[murdoch1976]

Fixed my own problem.

Did a simple initialize instead of an initialize2, and then performed the "AddAll" method instead to add the items. It no longer crashes when using the RemoveAt method.

Thanks everyone, I mean, me.

 

[cbal03]

I'm having some trouble with a List. I get the same aforementioned error when removing an item.
The list contains 172 items.
List is initialized by:

Dim myList As List
myList.Initialize

List is filled by:

myList = Regex.Split(Chr(13), myString) 'split up data returned

Value retrieval works ok.

filteredResultsCount = myList.Get(0) 'get the count stored in first position

This line generates the error.

myList.RemoveAt(0) 'remove the first item from the list

What's does this method require to work correctly?

Thanks

 

[Erel]

You are getting this error because you are wrapping an array with a list.

You can use this code to create a true dynamic list:

myList.Initialize
myList.AddAll(Regex.Split(...))

 

[cbal03]

Thank you very much Erel. Works nicely.
Sorry, I didn't consider what Regex.Split is actually doing.