Remove access to underlying containers inside Graph and Node.

src/main/org/insa/graph/Graph.java

@@ -1,7 +1,7 @@
 package org.insa.graph;
 
 import java.util.ArrayList;
-import java.util.Collections;
+import java.util.Iterator;
 import java.util.List;
 
 /**
@@ -11,7 +11,7 @@ import java.util.List;
  * holds a list of nodes and each node holds a list of its successors.
  *
  */
-public class Graph {
+public class Graph implements Iterable<Node> {
 
     // Map identifier.
     private final String mapId;
@@ -48,10 +48,28 @@ public class Graph {
     }
 
     /**
-     * @return Immutable view of the list of nodes of this graph.
+     * Fetch the node with the given ID.
+     * 
+     * Complexity: O(1).
+     * 
+     * @param id ID of the node to fetch.
+     * 
+     * @return Node with the given ID.
      */
-    public List<Node> getNodes() {
-        return Collections.unmodifiableList(nodes);
+    public Node get(int id) {
+        return this.nodes.get(id);
+    }
+
+    /**
+     * @return Number of nodes in this graph.
+     */
+    public int size() {
+        return this.nodes.size();
+    }
+
+    @Override
+    public Iterator<Node> iterator() {
+        return this.nodes.iterator();
     }
 
     /**
@@ -78,7 +96,7 @@ public class Graph {
         }
         for (Node node: nodes) {
             Node orig = trNodes.get(node.getId());
-            for (Arc arc: node.getSuccessors()) {
+            for (Arc arc: node) {
                 if (arc.getRoadInformation().isOneWay()) {
                     Node dest = trNodes.get(arc.getDestination().getId());
                     dest.addSuccessor(new ArcBackward(new ArcForward(orig, dest, arc.getLength(),

src/main/org/insa/graph/Node.java

@@ -2,7 +2,7 @@ package org.insa.graph;
 
 import java.util.ArrayList;
 import java.util.Collections;
-import java.util.List;
+import java.util.Iterator;
 
 /**
  * Class representing a Node in a {@link Graph}.
@@ -13,7 +13,7 @@ import java.util.List;
  * Nodes are comparable based on their ID.
  *
  */
-public class Node implements Comparable<Node> {
+public class Node implements Comparable<Node>, Iterable<Arc> {
 
     /**
      * Link the two given nodes with one or two arcs (depending on roadInformation),
@@ -94,10 +94,22 @@ public class Node implements Comparable<Node> {
     }
 
     /**
-     * @return Immutable view of the list of successors of this node.
+     * @return Number of successors of this node.
      */
-    public List<Arc> getSuccessors() {
-        return Collections.unmodifiableList(successors);
+    public int getNumberOfSuccessors() {
+        return this.successors.size();
+    }
+
+    /**
+     * @return true if this node has at least one successor.
+     */
+    public boolean hasSuccessors() {
+        return !this.successors.isEmpty();
+    }
+
+    @Override
+    public Iterator<Arc> iterator() {
+        return this.successors.iterator();
     }
 
     /**

src/main/org/insa/graph/io/BinaryPathReader.java

@@ -70,7 +70,7 @@ public class BinaryPathReader extends BinaryReader implements PathReader {
      * @throws IndexOutOfBoundsException if the node is not in the graph.
      */
     protected Node readNode(Graph graph) throws IOException {
-        return graph.getNodes().get(dis.readInt());
+        return graph.get(dis.readInt());
     }
 
 }