Polylines get connected from start and end | Google Maps | Android

Question

Problem is that when I draw polylines, they get connected from start and end point which is not supoosed to. I simply decode my polypoints (which are encoded strings from direction api) and then add them to polyoptions to draw polylines on map.

Here is my code below:

val options = PolylineOptions()
    options.color(Color.RED)
    options.width(10f)
    val list = booking.polyPointsList.flatMap { it.decodePoly() }
    options.addAll(list)

whats inside decodepoly()

fun String.decodePoly(): MutableList<LatLng> {
if (this.isEmpty()) return mutableListOf()
val poly = ArrayList<LatLng>()
var index = 0
val len = this.length
var lat = 0
var lng = 0

while (index < len) {
    var b: Int
    var shift = 0
    var result = 0
    do {
        b = this[index++].toInt() - 63
        result = result or (b and 0x1f shl shift)
        shift += 5
    } while (b >= 0x20)
    val dlat = if (result and 1 != 0) (result shr 1).inv() else result shr 1
    lat += dlat

    shift = 0
    result = 0
    do {
        b = this[index++].toInt() - 63
        result = result or (b and 0x1f shl shift)
        shift += 5
    } while (b >= 0x20)
    val dlng = if (result and 1 != 0) (result shr 1).inv() else result shr 1
    lng += dlng

    val p = LatLng(
        lat.toDouble() / 1E5,
        lng.toDouble() / 1E5
    )
    poly.add(p)
}

return poly

}

Answer 1

Probably in your decoded polyline point with start location coordinates exists twice as first and last point. So, try to remove last point in your list:

val options = PolylineOptions()
    options.color(Color.RED)
    options.width(10f)
    val list = booking.polyPointsList.flatMap { it.decodePoly() }
    list.removeLast() 
    ^^^^^^^^^^^^^^^^^ - add this line
    options.addAll(list)

Or, may be you add all of polyline points twice (or more). In that case "first point" also exists in polyline points at least twice:

     +--------------------- Cycle --------------------+
     |                                                |
first_point -> second_point -> ... last_point -> first_point -> ... -> last_point
\____________________  _____________________/    \__________   _________________/
                      V                                      V
        first time added points list               second time added points list