``` 001 002 003 004 005 006 007 008 009 010 011 012 013 014 015 016 017 018 019 020 021 022 023 024 025 026 027 028 029 030 031 032 033 034 035 036 037 038 039 040 041 042 043 044 045 046 047 048 049 050 051 052 053 054 055 056 057 058 059 060 061 062 063 064 065 066 067 068 069 070 071 072 073 074 075 076 077 078 079 080 081 082 083 084 085 086 087 088 089 090 091 092 093 094 095 096 097 098 099 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 ``` ```package horstmann.ch08_graphed; import java.awt.Graphics2D; import java.awt.geom.Point2D; import java.awt.geom.Rectangle2D; import java.io.Serializable; import java.util.ArrayList; import java.util.Collections; import java.util.List; /** A graph consisting of selectable nodes and edges. */ public abstract class Graph implements Serializable { private static final long serialVersionUID = 2008L; /** Constructs a graph with no nodes or edges. */ public Graph() { nodes = new ArrayList(); edges = new ArrayList(); } /** Adds an edge to the graph that joins the nodes containing the given points. If the points aren't both inside nodes, then no edge is added. @param e the edge to add @param p1 a point in the starting node @param p2 a point in the ending node */ public boolean connect(Edge e, Point2D p1, Point2D p2) { Node n1 = findNode(p1); Node n2 = findNode(p2); if (n1 != null && n2 != null) { e.connect(n1, n2); edges.add(e); return true; } return false; } /** Adds a node to the graph so that the top left corner of the bounding rectangle is at the given point. @param n the node to add @param p the desired location */ public boolean add(Node n, Point2D p) { Rectangle2D bounds = n.getBounds(); n.translate(p.getX() - bounds.getX(), p.getY() - bounds.getY()); nodes.add(n); return true; } /** Finds a node containing the given point. @param p a point @return a node containing p or null if no nodes contain p */ public Node findNode(Point2D p) { for (int i = nodes.size() - 1; i >= 0; i--) { Node n = nodes.get(i); if (n.contains(p)) return n; } return null; } /** Finds an edge containing the given point. @param p a point @return an edge containing p or null if no edges contain p */ public Edge findEdge(Point2D p) { for (int i = edges.size() - 1; i >= 0; i--) { Edge e = edges.get(i); if (e.contains(p)) return e; } return null; } /** Draws the graph @param g2 the graphics context */ public void draw(Graphics2D g2) { for (Node n : nodes) n.draw(g2); for (Edge e : edges) e.draw(g2); } /** Removes a node and all edges that start or end with that node @param n the node to remove */ public void removeNode(Node n) { for (int i = edges.size() - 1; i >= 0; i--) { Edge e = edges.get(i); if (e.getStart() == n || e.getEnd() == n) edges.remove(e); } nodes.remove(n); } /** Removes an edge from the graph. @param e the edge to remove */ public void removeEdge(Edge e) { edges.remove(e); } /** Gets the smallest rectangle enclosing the graph @param g2 the graphics context @return the bounding rectangle */ public Rectangle2D getBounds(Graphics2D g2) { Rectangle2D r = null; for (Node n : nodes) { Rectangle2D b = n.getBounds(); if (r == null) r = b; else r.add(b); } for (Edge e : edges) r.add(e.getBounds(g2)); return r == null ? new Rectangle2D.Double() : r; } /** Gets the node types of a particular graph type. @return an array of node prototypes */ public abstract Node[] getNodePrototypes(); /** Gets the edge types of a particular graph type. @return an array of edge prototypes */ public abstract Edge[] getEdgePrototypes(); /** Gets the nodes of this graph. @return an unmodifiable list of the nodes */ public List getNodes() { return Collections.unmodifiableList(nodes); } /** Gets the edges of this graph. @return an unmodifiable list of the edges */ public List getEdges() { return Collections.unmodifiableList(edges); } private ArrayList nodes; private ArrayList edges; } ```