How to build a polygon using segments and points

static void constructPolygons()throws Exception{
    //Build a polygon segment by segment.
    //Create the segments and rings. If this is a single-part polygon you can add
    //segments directly to the polygon and it creates the ring internally.
    //You cannot reuse the same ring object. Also, when rings are added to the polygon 
    //it takes ownership of them. You cannot reuse a ring for building another polygon. 
    //These same restrictions also apply to segments.

    ICircularArc circularArc = new CircularArc();
    IBezierCurveGEN bezierCurve = new BezierCurve();
    ISegmentCollection ring1 = new Ring();
    ISegmentCollection ring2 = new Ring();
    ring1.addSegment((ISegment)circularArc, null, null);
    ring2.addSegment((ISegment)bezierCurve, null, null);

    IPolygon polygon = new Polygon();
    //Always define the spatial reference of new top-level geometries.
    //polygon.SpatialReference = ... code skipped.
    IGeometryCollection geometryCollection = (IGeometryCollection)polygon;
    geometryCollection.addGeometry((IGeometry)ring1, null, null);
    geometryCollection.addGeometry((IGeometry)ring2, null, null);

    //At this point, you have constructed a _shell_ geometry. It consists of one 
    //polygon containing two rings, each of which contains one segment. 
    //However, the coordinates of those segments have not been defined. 
    //Because you still have references to those segments, you can define their 
    //coordinates now.
    //Circular arc.
    IPoint centerPoint = new Point();
    centerPoint.setX( - 10);
    centerPoint.setY(0);
    circularArc.putCoordsByAngle(centerPoint, 0, 2 * Math.PI, 10);

    //Bézier curve.
    IPoint[] controlPoints = new IPoint[4];
    for (int i = 0; i < controlPoints.length; i++){
        controlPoints[i] = new Point();
    }

    controlPoints[0].setX(10);
    controlPoints[0].setY(0);
    controlPoints[1].setX(10);
    controlPoints[1].setY(10);
    controlPoints[2].setX(20);
    controlPoints[2].setY(10);
    controlPoints[3].setX(10);
    controlPoints[3].setY(0);
    bezierCurve.putCoords(controlPoints);

    //The polygon has now been defined. When changing segment coordinates directly 
    //like this, you need to be careful to let the top-level geometry know that
    //things have changed underneath it so that it can delete any cached properties 
    //that it might be maintaining, such as envelope, length, area, etc.
    //When you use certain methods on the top-level geometry implementation 
    //of IGeometryCollection interface, like AddGeometry, it will automatically
    //invalidate any cached properties.
    geometryCollection.geometriesChanged();

    //Build another polygon from a bunch of points. As before, assume that 
    //two parts (rings) need to be created. If the polygon is a single part, you can
    //add the points directly to the polygon without creating a ring.
    IGeometryCollection pointPolygon = new Polygon();

    //Define the spatial reference of the new pointPolygon here, code skipped.
    //As previously stated, the rings used for the first polygon cannot be reused.
    ring1 = new Ring();
    ring2 = new Ring();

    //At 9.2, the recommended way to add arrays of points to a geometry is to use 
    //the IGeometryBridge2 interface on the GeometryEnvironment singleton object.
    IGeometryBridge2 geometryBridge = new GeometryEnvironment();

    _WKSPoint[] wksPoints1 = new _WKSPoint[ring1.getSegmentCount()];
    geometryBridge.setWKSPoints((IPointCollection4)ring1, wksPoints1);
    _WKSPoint[] wksPoints2 = new _WKSPoint[ring2.getSegmentCount()];
    geometryBridge.setWKSPoints((IPointCollection4)ring2, wksPoints2);

    pointPolygon.addGeometry((IGeometry)ring1, null, null);
    pointPolygon.addGeometry((IGeometry)ring2, null, null);
    //The point polygon is now defined.
}