Could not activate JNI Handle

Question

_{Thursday, July 13, 2017 7:48 AM}

Hi! I want to customize viewpager to make it work vertically. But when setting contentview app cannot create an instance of it and give this error:

System.NotSupportedException: Could not activate JNI Handle 0xeab00029 (key_handle 0x41357db0) of Java type 'md5b3f8461ca967df4f0978d2e01bf012d6/VViewPager' as managed type 'App3.Widgets.VViewPager'.

The custom viewpager:

namespace App3.Widgets
{
    public class VViewPager : ViewPager
    {
        public VViewPager(Context c) : base(c) { Initialize(); }
        public VViewPager(Context c, Android.Util.IAttributeSet attrs) : base(c, attrs) { Initialize(); }
        public VViewPager(IntPtr jr, JniHandleOwnership transfer) : base(jr, transfer) { Initialize(); }

        private void Initialize()
        {
            SetPageTransformer(true, new VerticalPageTransformer());

            OverScrollMode = OverScrollMode.Never;
        }

        private MotionEvent SwapXandY(MotionEvent ev)
        {
            ev.SetLocation(ev.GetY() / Height * Width, ev.GetX() / Width * Height);
            return ev;
        }

        public override bool OnInterceptTouchEvent(MotionEvent ev) => base.OnInterceptTouchEvent(SwapXandY(ev));

        public override bool OnTouchEvent(MotionEvent ev) => base.OnTouchEvent(SwapXandY(ev));

        private class VerticalPageTransformer : IPageTransformer
        {
            //some codes for changing behavior
        }

    }
}

All replies (6)

_{Tuesday, July 18, 2017 6:09 PM ✅Answered}

Answer is provided here : http://stackoverflow.com/a/10603714/748199 Any method that modifies View before it is created can cause this, in my case: Initialize()

_{Monday, December 11, 2017 11:54 PM}

Hi, Im having the same issue, What did you have to do to rectify this? Where did you call initialise? Thanks

_{Tuesday, December 12, 2017 11:02 AM}

Hi! I made Initialize() public and I call it in my activity or anywhere that view is found or created.

_{Tuesday, December 12, 2017 11:57 AM}

Thanks you are a gent!! Just one other thing did you manage to get the verticalviewpager to slide when swipe up and down rather than left and right?

_{Tuesday, December 12, 2017 12:01 PM}

Actually i found it, thanks I never added SwapXandY(ev)

_{Wednesday, April 15, 2020 7:32 PM}

1.Install-Package SQLite-Net-PCL 2.in properties of project go to android manifest tab and give read-external-storage and write-external-storage. 3.in constructor of connection class write this code.

    private string dbpath = "";
    private string dbName = "YourDB";
    SQLiteConnection db;
    public FriendManagMent()
    {
        dbpath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal);

db=new SQLiteConnection(Path.Combine(dbpath,dbName));

        db.CreateTable<Friend>();     
    }