diff --git a/java/src/main/java/org/softwareheritage/graph/NodesFiltering.java b/java/src/main/java/org/softwareheritage/graph/NodesFiltering.java
--- a/java/src/main/java/org/softwareheritage/graph/NodesFiltering.java
+++ b/java/src/main/java/org/softwareheritage/graph/NodesFiltering.java
@@ -3,19 +3,42 @@
 import java.util.ArrayList;
 
 /**
+ * <h3>NodesFiltering</h3>
+ * <p>
  * class that manages the filtering of nodes that have been returned after a visit of the graph.
- * parameterized by a string that represents either no filtering (*) or a set of node types
+ * parameterized by a string that represents either no filtering (*) or a set of node types.
+ * </p>
  *
- * Exemples of query :
+ * <ul>
  *
- * graph/visit/nodes/swh:1:rel:0000000000000000000000000000000000000010 return_types==rev will only
- * return 'rev' nodes.
+ * <li>graph/visit/nodes/swh:1:rel:0000000000000000000000000000000000000010 return_types==rev will
+ * only return 'rev' nodes.</li>
  *
- * graph/visit/nodes/swh:1:rel:0000000000000000000000000000000000000010 return_types==rev,snp,cnt
- * will only return 'rev' 'snp' 'cnt' nodes.
+ * <li>graph/visit/nodes/swh:1:rel:0000000000000000000000000000000000000010
+ * return_types==rev,snp,cnt will only return 'rev' 'snp' 'cnt' nodes.</li>
  *
- * graph/visit/nodes/swh:1:rel:0000000000000000000000000000000000000010 return_types==* will return
- * all the nodes bec.
+ * <li>graph/visit/nodes/swh:1:rel:0000000000000000000000000000000000000010 return_types==* will
+ * return all the nodes.</li>
+ * </ul>
+ *
+ * How to use NodesFiltering :
+ *
+ * <pre>
+ * {@code
+ *  Long id1 = .... // graph.getNodeType(id1) == CNT
+ *  Long id2 = .... // graph.getNodeType(id2) == SNP
+ *  Long id3 = .... // graph.getNodeType(id3) == ORI
+ *  ArrayList<Long> nodeIds = nez ArrayList<Long>();
+ *  nodeIds.add(id1); nodeIds.add(id2); nodeIds.add(id3);
+ *
+ *  NodeFiltering nds = new NodesFiltering("snp,ori"); // we allow only snp node types to be shown
+ *  System.out.println(nds.filterByNodeTypes(nodeIds,graph)); // will print id2, id3
+ *
+ *  nds = NodesFiltering("*");
+ *  System.out.println(nds.filterByNodeTypes(nodeIds,graph)); // will print id1, id2 id3
+ *
+ * }
+ * </pre>
  */
 
 public class NodesFiltering {
@@ -25,7 +48,7 @@
 
     /**
      * Default constructor, in order to handle the * case (all types of nodes are allowed to be
-     * returned)
+     * returned). allowedNodesTypes will contains [SNP,CNT....] all types of nodes.
      *
      */
     public NodesFiltering() {
@@ -34,6 +57,12 @@
     }
 
     /**
+     * Constructor
+     *
+     * @param strTypes a formatted string describing the types of nodes we want to allow to be shown.
+     *
+     *            NodesFilterind("cnt,snp") will set allowedNodesTypes to [CNT,SNP]
+     *
      */
     public NodesFiltering(String strTypes) {
         restricted = true;
@@ -44,16 +73,27 @@
         }
     }
 
+    /**
+     * Check if the type given in parameter is in the list of allowed types.
+     *
+     * @param typ the type of the node.
+     */
     public boolean typeIsAllowed(Node.Type typ) {
         return this.allowedNodesTypes.contains(typ);
     }
 
     /**
+     * <p>
      * the function that filters the nodes returned, we browse the list of nodes found after a visit and
      * we create a new list with only the nodes that have a type that is contained in the list of
      * allowed types (allowedNodesTypes)
+     * </p>
+     *
+     * @param nodeIds the nodes founded during the visit
+     * @param g the graph in order to find the types of nodes from their id in nodeIds
+     * @return a new list with the id of node which have a type in allowedTypes
+     *
      *
-     * We need the graph in order to find the types of nodes.
      */
     public ArrayList<Long> filterByNodeTypes(ArrayList<Long> nodeIds, Graph g) {
         ArrayList<Long> filteredNodes = new ArrayList<Long>();