// Exercise 17.1 public static final String[] NAMES = {null, null, null, "Triangle", "Square", "Pentagon", "Hexagon", "Heptagon", "Octagon", "Nonagon", "Decagon"}; @Override public String toString() { StringBuilder str = new StringBuilder(); if (npoints < NAMES.length) { str.append(NAMES[npoints]); } else { str.append("Polygon"); } // append the list of vertexes str.append('['); for (int i = 0; i < npoints; i++) { if (i > 0) { str.append(", "); } // append the next (x, y) point str.append('('); str.append(xpoints[i]); str.append(", "); str.append(ypoints[i]); str.append(')'); } str.append(']'); return str.toString(); }