Dim FileName As String = "1.pdf"
Msgbox ( File.Exists (File.DirInternal, FileName),"")
Dim Intent1 As Intent
Intent1.Initialize(Intent1.ACTION_VIEW, "file://" & File.Combine(File.DirInternal , FileName))
Intent1.SetComponent("android/com.android.internal.app.ResolverActivity")
Intent1.SetType("application/pdf")
Intent1.WrapAsIntentChooser ("Choose Viewer")
StartActivity(Intent1)