--- a/backend/src/main/java/org/dive4elements/river/importer/ImportTimeInterval.java	Fri May 03 12:51:29 2013 +0200
+++ b/backend/src/main/java/org/dive4elements/river/importer/ImportTimeInterval.java	Fri May 03 13:06:14 2013 +0200
@@ -31,29 +31,30 @@
     }
 
     public ImportTimeInterval(Date startTime) {
-        this.startTime = startTime;
-        this.stopTime = null;
+        this(startTime, null);
     }
 
     public ImportTimeInterval(Date startTime, Date stopTime) {
-	Date start;
-	Date stop;
-	if (startTime == null) {
-	    start = stopTime;
-	    stop = null;
-	}
-	else {
-	    start = startTime;
-	    stop = stopTime;
-	}
 
-        if (stop != null && start.after(stop)) {
-            this.stopTime = start;
-            this.startTime = stop;
+        if (startTime != null && stopTime == null) {
+            this.startTime = startTime;
+            this.stopTime = null;
+        }
+        else if (startTime == null && stopTime != null) {
+            this.startTime = stopTime;
+            this.stopTime = null;
+        }
+        else if (startTime == null && stopTime == null) {
+            throw new IllegalArgumentException("Both dates are null.");
         }
         else {
-            this.startTime = start;
-            this.stopTime  = stop;
+            if (startTime.after(stopTime)) {
+                Date t = startTime;
+                startTime = stopTime;
+                stopTime = t;
+            }
+            this.startTime = startTime;
+            this.stopTime = stopTime;
         }
     }
 
@@ -102,5 +103,10 @@
         }
         return peer;
     }
+
+    @Override
+    public String toString() {
+        return "start time: " + startTime + ", stop time: " + stopTime;
+    }
 }
 // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :