I have a List in my java file. java.util.List, and...

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[fradiati]

I have a List in my java file. java.util.List, and i have a function in my kotlin class which add theese items to a mutableList. I get UnsupportedOperationException and i can"t solve it with stackoverFlow posts. What can I do?

[diesieben07]

How is myMutableList created? And can you show the stacktrace?

[fradiati]

this is my adapter

[fradiati]

abstract class BaseRecyclerAdapter<T>(
       private var masterList: MutableList<T> = mutableListOf()
) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {

[fradiati]

fun updateList(list: List<T>) {
    masterList.clear()
    masterList.addAll(list as MutableList<T>)
    notifyDataSetChanged()
}

[diesieben07]

Why are you casting to MutableList<T>? addAll accepts a plain List<T>, no need for a mutable list.

[fradiati]

2019-12-09 091955.307 12705-12705 E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.velemjaro.app.debug, PID: 12705
java.lang.UnsupportedOperationException
at java.util.AbstractList.add(AbstractList.java:148)
at java.util.AbstractList.add(AbstractList.java:108)
at java.util.AbstractCollection.addAll(AbstractCollection.java:344)
at BaseRecyclerAdapter.updateList(BaseRecyclerViewAdapter.kt:12)

[fradiati]

yes i know, but i try everything yes

[fradiati]

yet

[diesieben07]

And that error should be impossible to get with that code, because mutableListOf returns an ArrayList, which overrides add

[fradiati]

so it was my original function

[fradiati]

fun updateList(list: List<T>) {
    masterList.clear()
    masterList.addAll(list)
    notifyDataSetChanged()
}

[fradiati]

but i get this error every time

[diesieben07]

If you put a breakpoint at the start of that method, is masterList still an ArrayList?

[fradiati]

adapterBlog.updateList((List<BlogPost>) results);

[fradiati]

masterList = {Collections$EmptryList@19456} size = 0

[diesieben07]

Are you assigning masterList anywhere else? Like masterList = ... anywhere?

[fradiati]

just in the constructor

[diesieben07]

But then it can't be Collections.EmptyList...