IntelliJ idea Error Refactoring can not be performed

IntelliJ idea Error Refactoring can not be performed

References

Reference NO 1

http://stackoverflow.com/questions/15190035/intellij-idea-error-refactoring-can-not-be-performed-class-file-is-read-only

Reference NO 2

http://www.jetbrains.com/idea/features/refactoring.html

Reference NO 3

http://confluence.jetbrains.com/display/IDEADEV/IntelliJ+IDEA+12.1.3+Release+Notes

Reference NO 4

http://jetbrains.dzone.com/articles/top-20-refactoring-features

Reference NO 5

http://www.slideshare.net/intelliyole/implementing-refactorings-in-intellij-idea-presentation

Reference NO 6

http://mac.softpedia.com/progChangelog/IntelliJ-IDEA-Changelog-51543.html

Reference NO 7

http://dl.acm.org/citation.cfm?id=1636655

Reference NO 8

http://c2.com/cgi/wiki?EclipseVsIdea