Add a method for hashing and comparison

app/src/main/java/ch/nuth/zhaw/exbox/MyCompetitor.java

@@ -47,19 +47,39 @@ public class MyCompetitor implements Comparable<MyCompetitor> {
 
     @Override
     public int compareTo(MyCompetitor o) {
-        // to be done
-        return -1;
+        int result = getName().compareTo(o.getName());
+
+        if (result == 0) {
+            result = getTime().compareTo(o.getTime());
+
+            if (result == 0) {
+                result = rank - o.rank;
+            }
+        }
+
+        return result;
     }
 
     @Override
     public int hashCode() {
-        // to be done
-        return -1;
+        int hashCode = 1;
+        hashCode *= 13;
+        hashCode += name.hashCode();
+        hashCode *= 17;
+        hashCode += time.hashCode();
+        hashCode *= 31;
+        return hashCode + rank;
     }
 
     @Override
     public boolean equals (Object o) {
-        // to be done
+        if (o instanceof MyCompetitor c) {
+            return hashCode() == c.hashCode() &&
+                getName().equals(c.getName()) &&
+                getTime().equals(c.getTime()) &&
+                rank == c.rank;
+        } else {
             return false;
         }
+    }
 }