Minor changes to Person

src/tp04/Person.java

+package tp04;
+
 public class Person {
 
-    private int ID;
+    final private int ID;
     private String forename;
     private String name;
 
     private static int counter;
 
-    public Person(String name, String forename) {
+    public Person(String forename, String name) {
         this.forename = forename;
         this.name = name;
 
@@ -39,8 +41,12 @@ public class Person {
     }
 
     public boolean equals(Object other) {
+        if (other == null) {
+            return false;
+        }
         if (other.getClass() == this.getClass()) {
-            return other.ID  == this.ID;
+            Person otherPerson = (Person) other;
+            return otherPerson.getID() == this.ID;
         }
         return false;
     }