private void toggleLabels() {
            hasLabels = !hasLabels;

            if (hasLabels) {
                hasLabelForSelected = false;
                chart.setValueSelectionEnabled(hasLabelForSelected);
            }

            generateData();
        }
Adds lines to data, after that data should be set again with
{@link LineChartView#setLineChartData(LineChartData)}. Last 4th line has non-monotonically x values.
hellocharts-samples/src/lecho/lib/hellocharts/samples/LineChartActivity.java