How to Get Buffer for Road in Arcgis Android? -

i developing 1 application using arcgis. here want implement buffer both point , line segments (road).

here buffer point using method

geometryengine.buffer(geometry1,mmapview.getspatialreference(), meters, null) 

where road if single segment able draw buffer.i unable draw buffer multiple segments.

please give me solution this.i want

my code

 polygon = geometryengine.buffer(geometry1,                 mmapview.getspatialreference(), meters, null);         withingeometry = geometryengine.project(polygon,                 mmapview.getspatialreference(),                 mmapview.getspatialreference());        simplefillsymbol sls = new simplefillsymbol(color.transparent);         sls.setalpha(75);          graphic graphics= new graphic(withingeometry,sls);         buffergraphiclayer.addgraphic(graphics);         mmapview.addlayer(buffergraphiclayer); 

there 2 options should produce result want, both involving geometryengine.union(geometry[], spatialreference) method:

1. call union on array of geometry objects want buffer produce single geometry, , call buffer on single geometry.
2. call buffer on array of geometry objects want buffer produce polygon array, , call union on polygon array.