The '''blank final''', which was introduced in Java 1.1, is a final variable whose declaration lacks an initializer.<ref>{{cite book|last=Flanagan|first=David |title=Java in a Nutshell|url=http://web.deu.edu.tr/doc/oreily/java/javanut/ch05_06.htm|edition=2nd Edition|date=May 1997 |publisher=O'Reilly|isbn=1-56592-262-X|chapter=Chapter 5 Inner Classes and Other New Language Features:5.6 Other New Features of Java 1.1}}</ref><ref>{{cite web|url=http://java.sun.com/docs/books/jls/second_edition/html/typesValues.doc.html|title=Types, Values, and Variables|year=2000|work=Java Language Specification Chapter 4|publisher=Sun Microsystems, Inc|accessdate=23 July 2010}}</ref> A blank final can only be assigned once and must be unassigned when an assignment occurs. In order to do this, a Java compiler runs a flow analysis to ensure that, for every assignment to a blank final variable, the variable is definitely unassigned before the assignment; otherwise a compile-time error occurs.<ref>{{cite web|url=http://java.sun.com/docs/books/jls/second_edition/html/defAssign.doc.html|title=Definite Assignment|year=2000|work=Java Language Specification|publisher=Sun Microsystems, Inc.|accessdate=23 July 2010}}</ref>