--- a/backend/src/main/java/org/dive4elements/river/importer/ImportRange.java	Thu Sep 12 18:43:21 2013 +0200
+++ b/backend/src/main/java/org/dive4elements/river/importer/ImportRange.java	Thu Sep 12 18:58:19 2013 +0200
@@ -31,8 +31,30 @@
     }
 
     public ImportRange(BigDecimal a, BigDecimal b) {
-        this.a = a;
-        this.b = b;
+
+	// enforce a<b and set only a for zero-length ranges
+        if (a != null && b == null) {
+            this.a = a;
+            this.b = null;
+        }
+        else if (a == null && b != null) {
+            this.a = b;
+            this.b = null;
+        }
+        else if (a == null && b == null) {
+            throw new IllegalArgumentException("Both a and b are null.");
+        }
+        else if (a == b) {
+            this.a = a;
+            this.b = null;
+        }
+        else {
+            if (a.compareTo(b) == 1) {
+		BigDecimal t = a; a = b; b = t;
+            }
+            this.a = a;
+            this.b = b;
+        }
     }
 
     private static final int compare(BigDecimal a, BigDecimal b) {
@@ -48,12 +70,6 @@
         return a.compareTo(b);
     }
 
-    public void fixRangesOrder() {
-        if (compare(a, b) > 0) {
-            BigDecimal t = a; a = b; b = t;
-        }
-    }
-
     public int compareTo(ImportRange other) {
         int cmp = compare(a, other.a);
         if (cmp != 0) return cmp;