I'm using the com.codename1.charts lib but there isn't a whole lot of documentation. None of the chart demos use dashed or dotted lines and I assumed you could use BasicStroke.DASHED but changing this constant value does not seem to make a difference and keeps the line solid.
I'm using the following code:
colors.add(ColorUtil.GRAY);
styles.add(PointStyle.POINT);
strokes.add(BasicStroke.DASHED);
lineWeight.add(3);
XYMultipleSeriesRenderer renderer = buildRenderer(colors, styles, strokes, lineWeight);