many changes

src/Tuple.java

@@ -1,34 +1,61 @@
-public class Tuple2<T1, T2> {
+import java.util.Objects;
+import be.kuleuven.cs.som.annotate.*;
+
+
+/**
+ * A tuple implementation
+ *
+ * @param <T1> first element type
+ * @param <T2> second element type
+ *
+ *
+ * @version 1.0
+ * @author Arthur Bols & Leen Dereu
+ */
+@Value
+public class Tuple<T1, T2> {
+
 
     public final T1 item1;
     public final T2 item2;
 
-    public Tuple2(T1 x, T2 y) {
-        this.item1 = x;
-        this.item2 = y;
+
+    /**
+     *
+     * @param item1
+     *        The first element for this tuple
+     * @param item2
+     *        The second element for this tuple
+     */
+    private Tuple(T1 item1, T2 item2) {
+
+        if (item1 == null)
+            throw new IllegalArgumentException("item1 may not be null");
+        if (item2 == null)
+            throw new IllegalArgumentException("item2 may not be null");
+
+        this.item1 = item1;
+        this.item2 = item2;
     }
 
+    @Immutable
+    public static <T1, T2> Tuple<T1, T2> create(T1 item1, T2 item2){
+        return new Tuple<>(item1, item2);
+    }
 
     @Override
-    public boolean equals(final Object obj) {
-        if (this == obj)
-            return true;
-        if (obj == null)
-            return false;
-        if (!(obj instanceof Tuple2))
-            return false;
-        final Tuple2<?, ?> other = (Tuple2<?, ?>) obj;
-        if (_1 == null) {
-            if (other._1 != null)
-                return false;
-        } else if (!_1.equals(other._1))
-            return false;
-        if (_2 == null) {
-            if (other._2 != null)
-                return false;
-        } else if (!_2.equals(other._2))
-            return false;
-        return true;
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (!(o instanceof Tuple)) return false;
+        Tuple<?, ?> tuple = (Tuple<?, ?>) o;
+        return Objects.equals(item1, tuple.item1) &&
+                Objects.equals(item2, tuple.item2);
+    }
+
+    @Override
+    public int hashCode() {
+
+        return Objects.hash(item1, item2);
     }
 
 }