I have a shapefile that opens and looks like this:

Now I'm trying to draw a line of two points, which I click on this map; however, the code they give as an example QuickStart.javais extremely vague.
Here is their code:
package org.geotools.tutorial;
import java.io.File;
import org.geotools.data.FileDataStore;
import org.geotools.data.FileDataStoreFinder;
import org.geotools.data.simple.SimpleFeatureSource;
import org.geotools.map.FeatureLayer;
import org.geotools.map.Layer;
import org.geotools.map.MapContent;
import org.geotools.styling.SLD;
import org.geotools.styling.Style;
import org.geotools.swing.JMapFrame;
import org.geotools.swing.data.JFileDataStoreChooser;
import org.geotools.geometry.jts.JTSFactoryFinder;
import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.LineString;
public class Quickstart {
public static void main(String[] args) throws Exception {
File file = JFileDataStoreChooser.showOpenFile("shp", null);
if (file == null) {
return;
}
FileDataStore store = FileDataStoreFinder.getDataStore(file);
SimpleFeatureSource featureSource = store.getFeatureSource();
MapContent map = new MapContent();
map.setTitle("Quickstart");
Style style = SLD.createSimpleStyle(featureSource.getSchema());
Layer layer = new FeatureLayer(featureSource, style);
map.addLayer(layer);
JMapFrame.showMap(map);
}
}
Now that I'm confused about which method I should use to click two dots and draw a line between them?
Does anyone have any good resources? I read the GeoTools documentation and am still a bit confused.
I tried to make a common code on the site, but it does not appear on the map.
GeometryFactory geometryFactory = JTSFactoryFinder.getGeometryFactory( null );
Coordinate[] coords =
new Coordinate[] {new Coordinate(0, 2), new Coordinate(2, 0), new Coordinate(8, 6) };
LineString line = geometryFactory.createLineString(coords);
Style style2 = SLD.createLineStyle(Color.BLUE, 1);
Layer layer2 = new FeatureLayer(featureSource, style2);
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