From: Artur Signell <artur@vaadin.com>
Date: Mon, 16 Sep 2013 12:49:35 +0000 (+0300)
Subject: Clarified error message (#12583)
X-Git-Tag: 7.1.7~40
X-Git-Url: https://source.dussan.org/?a=commitdiff_plain;h=0e048a5ba6cf734485fc83cb3b264b8ff104ecb9;p=vaadin-framework.git

Clarified error message (#12583)

Change-Id: I542046158f6e78c8bb26aaee110bd5b123ae13e6
---

diff --git a/server/src/com/vaadin/ui/UI.java b/server/src/com/vaadin/ui/UI.java
index 0746431302..27f04c39e1 100644
--- a/server/src/com/vaadin/ui/UI.java
+++ b/server/src/com/vaadin/ui/UI.java
@@ -402,9 +402,12 @@ public abstract class UI extends AbstractSingleComponentContainer implements
      * @see #getSession()
      */
     public void setSession(VaadinSession session) {
-        if ((session == null) == (this.session == null)) {
+        if (session == null && this.session == null) {
             throw new IllegalStateException(
-                    "VaadinServiceSession has already been set. Old session: "
+                    "Session should never be set to null when UI.session is already null");
+        } else if (session != null && this.session != null) {
+            throw new IllegalStateException(
+                    "Session has already been set. Old session: "
                             + getSessionDetails(this.session)
                             + ". New session: " + getSessionDetails(session)
                             + ".");