Adding all heap classes and interface and specific exception.

data_structures/heaps/EmptyHeapException.java

@@ -0,0 +1,18 @@
+/**
+ * 
+ */
+package heaps;
+
+/**
+ * @author Nicolas Renard
+ * Exception to be thrown if the getElement method is used on an empty heap.
+ *
+ */
+@SuppressWarnings("serial")
+public class EmptyHeapException extends Exception {
+    
+    public EmptyHeapException(String message) {
+        super(message);
+    }
+
+}