CODEWITHSUNDEEP
androidkotlin
Emma Alden
Emma Alden

Reputation: 159

UnsupportedOperationException when trying to add an element into a MutableList

I'm trying to select and remove categories in a RecyclerView but i got UnsupportedOperationException with some specific phone brands(Android version 8 or 9).

My code:

private var categoriesDefault: MutableList<String> = mutableListOf()

override fun onItemSelected(position: Int, isSelected: Boolean) {
        if (isSelected){
            categoriesDefault.add(categoriesValues[position]) // i got error here
        }else{
            categoriesDefault.remove(categoriesValues[position])// i got error here
        }
    }

Exception:

Fatal Exception: java.lang.UnsupportedOperationException
       at java.util.AbstractList.add + 148(AbstractList.java:148)
       at java.util.AbstractList.add + 108(AbstractList.java:108)
       at com.blarma.high5.aui.base.wordsetting.CategoryFragment.onItemSelected + 19(CategoryFragment.kt:19)
       at com.blarma.high5.aui.base.wordsetting.CategoryAdapter$onBindViewHolder$1.onCheckedChanged + 42(CategoryAdapter.kt:42)
       at android.widget.CompoundButton.setChecked + 171(CompoundButton.java:171)
       at android.widget.CompoundButton.toggle + 127(CompoundButton.java:127)
       at android.widget.CompoundButton.performClick + 132(CompoundButton.java:132)
       at android.view.View.performClickInternal + 6585(View.java:6585)
       at android.view.View.access$3100 + 785(View.java:785)
       at android.view.View$PerformClick.run + 25921(View.java:25921)
       at android.os.Handler.handleCallback + 873(Handler.java:873)
       at android.os.Handler.dispatchMessage + 99(Handler.java:99)
       at android.os.Looper.loop + 201(Looper.java:201)
       at android.app.ActivityThread.main + 6810(ActivityThread.java:6810)
       at java.lang.reflect.Method.invoke(Method.java)
       at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run + 547(RuntimeInit.java:547)
       at com.android.internal.os.ZygoteInit.main + 873(ZygoteInit.java:873)

Upvotes: 0

Views: 1218

Answers (1)

Ishtdeep Hora
Ishtdeep Hora

Reputation: 320

The code seems to be correct. But the issue is in declaration. I think the mutableListOf which is generic is imposed by MutableList which is a subType of generic type. Every therefore, if you look into the documentation of kotlin. They always declare in this form mutableListOf or variable declaration as mutableListOf(variableList)

So, mutableList<T> returns MutableList<T>

Upvotes: 1

Related Questions