public final class PolylineCodec

Object
PolylineCodec

Reads and writes the encoded polyline format – the compact ASCII representation of a coordinate sequence that virtually every directions and routing service uses for route geometry (Google Directions, OSRM, Mapbox Directions, GraphHopper, Valhalla, OpenRouteService).

Use it to turn a route geometry straight into something drawable:

map.addPolyline(Polyline.fromEncoded(geometryFromMyDirectionsApi));

The encoding stores each coordinate as a zig-zag, base-64-ish delta from the previous one at a fixed decimal precision. Precision 5 is the original Google format and the OSRM/Google/GraphHopper default; precision 6 (polyline6) is what Valhalla and OSRM’s geometries=polyline6 emit. Decoding with the wrong precision yields coordinates off by a factor of ten, so pass the precision your service documents.

Methods

`public static` `List decode(String encoded)`	Decodes an encoded polyline at the default precision of 5.
`public static` `List decode(String encoded, int precision)`	Decodes an encoded polyline at an explicit decimal precision (5 for the classic format, 6 for `polyline6`).
`public static` `String encode(List points)`	Encodes `LatLng` vertices at the default precision of 5.
`public static` `String encode(List points, int precision)`	Encodes `LatLng` vertices at an explicit decimal precision.

Inherited methods

From Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait, clone

Method details

decode

public static List decode(String encoded)

Decodes an encoded polyline at the default precision of 5.

Parameters

encoded String: the encoded geometry, may be null

Returns

the decoded LatLng vertices, empty when encoded is null or blank

decode

public static List decode(String encoded, int precision)

Decodes an encoded polyline at an explicit decimal precision (5 for the classic format, 6 for polyline6).

Trailing bytes that do not form a complete coordinate pair – the usual symptom of a truncated response – are dropped rather than throwing, so a partial geometry still draws the coordinates it did carry. A value cut in half is discarded too: half a delta is not a coordinate, and emitting it would put a spurious vertex on the map and skew the route bounds. Decoding likewise stops at the first character outside the encoding’s alphabet instead of folding it into a coordinate.

Parameters

encoded String: the encoded geometry, may be null
precision int: the number of decimal digits the encoder scaled by, between 1 and 10

Returns

the decoded LatLng vertices, never null

Throws

IllegalArgumentException: when precision is outside 1 to 10, which would scale every coordinate into nonsense rather than fail

encode

public static String encode(List points)

Encodes LatLng vertices at the default precision of 5.

Parameters

points List: the vertices to encode, may be null

Returns

the encoded geometry, empty for a null or empty list

encode

public static String encode(List points, int precision)

Encodes LatLng vertices at an explicit decimal precision.

Parameters

points List: the vertices to encode, may be null
precision int: the number of decimal digits to scale by, between 1 and 10

Returns

the encoded geometry, never null

Throws

IllegalArgumentException: when precision is outside 1 to 10