Fixed a null pointer exception introduced by r4909

git-svn-id: svn://svn.code.sf.net/p/tigervnc/code/trunk@4911 3789f03b-4d11-0410-bbf8-ca57d06f2519
diff --git a/java/com/tigervnc/vncviewer/VncViewer.java b/java/com/tigervnc/vncviewer/VncViewer.java
index 85da249..bb2cbab 100644
--- a/java/com/tigervnc/vncviewer/VncViewer.java
+++ b/java/com/tigervnc/vncviewer/VncViewer.java
@@ -143,7 +143,7 @@
         usage();
       }
 
-      if (vncServerName.getValue() == null)
+      if (vncServerName.getValue() == "")
         vncServerName.setParam(argv[i]);
     }
 
@@ -366,7 +366,7 @@
   StringParameter passwordFile
   = new StringParameter("PasswordFile",
                         "Password file for VNC authentication",
-                        null);
+                        "");
   AliasParameter passwd
   = new AliasParameter("passwd",
                        "Alias for PasswordFile",