Java Declarative Refactorings


Apache NetBeans provides language and tools to define custom Java refactorings, and run them on a specified source files, inside the NetBeans IDE, on command line, or using Apache Maven. Any standard Java "hint" may be run using these means as well.

Declarative Refactoring File

The easiest way to define custom Java refactorings is to place then in a file with extension ".hint", and place the file into the META-INF/upgrade folder of the corresponding sources. Maven, the command line tools or NetBeans all look into this location for custom refactorings.

For maven projects, this typically means placing the file into src/main/resources/META-INF/upgrade/<name>.hint.

The format of the file is described here.

Using Maven to Run Declarative Refactorings

To use run the declarative hints in a Maven project, add the tool to the build plugins in pom.xml:


And declare the hints in .hint files under src/main/resources/META-INF/upgrade, for example:


To get warnings for the declarative hints, run jackpot30:analyze:

$ mvn -q jackpot30:analyze
.../src/main/java/sample/sample/ warning: [convert] convert
        System.err.println("args=" + args);

To apply the changes produced by the declarative hints, run jackpot30:apply:

$ mvn -q jackpot30:apply && git diff
diff --git a/src/main/java/sample/sample/ b/src/main/java/sample/sample/
index a8465f2..c558be1 100644
--- a/src/main/java/sample/sample/
+++ b/src/main/java/sample/sample/
@@ -11,7 +11,7 @@ package sample.sample;
 public class Test {
     public static void main(String... args) {
-        System.err.println("args=" + args);
+        System.out.println("args=" + args);
         new Object() {
             public String toString() { return super.toString(); }

Please note the changes will be applied directly to the working copy of the files.