Question

Begginer android programer, I want add and remove item from String list when user click on listitem, but i get operation not supported error on trying to do that. See following code to understand what i want to do.

@Override
    protected void onListItemClick(ListView l, View v, int position, long id) {
        super.onListItemClick(l, v, position, id);
        if(myList != null)
        {
            StringBuilder stringBuilder = new StringBuilder();
            if(myList.contains(mylist1.get(position).getPackageName()))
            {
                for(int i = 0; i < myList.size(); i++)
                {
                    if(myList.get(i).equals(mylist1.get(position).getPackageName()))
                        continue;
                    if((myList.size() - 1) != i)
                        stringBuilder.append(myList.get(i)).append(separator);
                    else
                        stringBuilder.append(myList.get(i));
                }
                editor.putString("mypreference", stringBuilder.toString());
                mylistt1.get(position).setDisabled(false);
       //error happens in following
                myList.remove(mylist1.get(position).getPackageName());
            }
      }
}

Here is the logcat

04-08 11:33:00.030: ERROR/AndroidRuntime(533): FATAL EXCEPTION: main
        java.lang.UnsupportedOperationException
        at java.util.AbstractList.remove(AbstractList.java:638)
        at java.util.AbstractList$SimpleListIterator.remove(AbstractList.java:75)
        at java.util.AbstractCollection.remove(AbstractCollection.java:229)
        at com.mypackage.myActivity.onListItemClick(myActivity.java:82)
        at android.app.ListActivity$2.onItemClick(ListActivity.java:319)
        at android.widget.AdapterView.performItemClick(AdapterView.java:292)
        at android.widget.AbsListView.performItemClick(AbsListView.java:1058)
        at android.widget.AbsListView$PerformClick.run(AbsListView.java:2514)
        at android.widget.AbsListView$1.run(AbsListView.java:3168)
        at android.os.Handler.handleCallback(Handler.java:605)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:4340)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
        at dalvik.system.NativeStart.main(Native Method)

Answer 1

If myList has a datatype of List, it is immutable. You cannot make changes to it. So you would get operation not supported exception. Change myList datatype to an ArrayList before trying to make the changes.