Open one of your
java files that defines some class having a number of instance variables. Double click to select one of them (on the declaration or any place it's used, doesn't matter). Press Alt+Shift+R. This invokes the deceptively simple but most common refactoring - rename.
Enter the new name for the field and press OK to rename it or Preview to see what the changes will be before you perform the operation. Eclipse will change the name of *all* occurrences of the field. One rename could result in dozens or hundreds of changes across your project, and it's all undoable.
This is *way* better than a simple text substitution. For example, it's smart enough to not rename fields with the same name in other classes. It won't change the field name if it appears in comments or strings unless you tell it to. And if you have getter/setter functions with standard names, for example if your field is "window" and you have getWindow() and setWindow(), Eclipse will offer to rename those for you too.
Rename works on any Java objects - fields, variables, methods, interfaces, classes, compilation units. packages, you name it. For example if you rename class Foo to class Bar, it will change the Foo.java filename to be Bar.java. If you rename a package to take out a level it will reorganize your directory structure and change all the package and import statements that reference that name. Currently it only works for Java but the CDT developers are working to add support for C/C++ as well.
Not bad for pressing three little keys.
