I have tried to use the Formatter with a custom format (modifications introduced with ROASTER-37 (https://issues.jboss.org/browse/ROASTER-37)): Formatter.format(Properties, JavaClassSource) Here some findings / information: h2. 1/ Obtain the Properties object When you export the Java Formatter format from Eclipse (see screenshot), you obtain an xml file. The settings contained in the file are correct (setting tag: id attribute & value attribute) but I think that the format is not suitable. Alternative is to check the /.settings/org.eclipse.jdt.core.prefs of your java project (if you have checked the “Enabled project specific settings” in the project preferences, the current formatter settings will also be stored there). I my opinion this file contains too much entries (non jdt-formatter stuff), but the format is suitable and it can be loaded into a java.util.Properties object. Here is how (based on google guava): //imports: com.google.common.io.Files, com.google.common.base.Charsets //propFile is a java.io.File BufferedReader inputStream = Files.+newReader+(propFile, Charsets.+UTF_8+); Properties prop = *new* Properties(); 1. prop.load(inputStream); If you want to do some cleanup, you can extract the lines from the org.eclipse.jdt.core.prefs file into a roaster_formatter.properties file. Basically you will need the lines starting with org.eclipse.jdt.core.formatter. The keys are defined in this Javadoc: DefaultCodeFormatterConstants (http://help.eclipse.org/luna/topic/org.eclipse.jdt.doc.isv/reference/api/...). h2. 2/ Make the formatter working: set the version of the java source I noticed that my formatter was not working with all my JavaClassSource classes. After a long debug session, I found out why it was not working. A breakpoint in RecordedParsingInformation.updateRecordedParsingInformation(CompilationResult) shows that is some cases, compilationResult.problems is not null: Pb(596) Syntax error, annotations are only available if source level is 1.5 or greater The JDT cannot compile a file that cannot be parsed. It took me a while to understand how to set the source level. If you do nothing, the method DefaultCodeFormatter.getDefaultCompilerOptions() sets the version to "1.3". Here the corresponding code snippet: Object sourceOption = *this*.options.get(CompilerOptions.OPTION_Source); *if* (sourceOption != *null*) { *this*.defaultCompilerOptions.put(CompilerOptions.OPTION_Source, sourceOption); } *else* { *this*.defaultCompilerOptions.put(CompilerOptions.OPTION_Source, CompilerOptions.VERSION_1_3); } To set the version to another version (1.7 for example), just add the line in your properties file: org.jboss.forge.roaster._shade.org.eclipse.jdt.core.compiler.source=1.7 I am not sure why this org.jboss..._shade prefix is necessary, but without this prefix, it is not working. This might be related with ROASTER-12 (https://issues.jboss.org/browse/ROASTER-12). h2. 3/ Side-note: Formatter.format(Properties, JavaClassSource) calls the formatter twice. The current implementation of org.jboss.forge.roaster.model.util.Formatter.format(Properties, JavaClassSource) calls the JDT Formatter twice. The implementation looks like this: /**     * Format the given {@link JavaClassSource}, using the given Eclipse code format {@link Properties}.     */ *public* *static* String format(Properties prefs, JavaClassSource javaClass)    { *return* +format+(prefs, javaClass.toString());    } A break point at the beginning of the private method: Formatter._format(String, CodeFormatter) shows why: - First call: because of the AbstractJavaSource#toString() implementation. The class gets formatted with the default settings. - Second call: the expected one. I hope this feedback is useful for other developers using roaster. Posted by forums Original post: https://developer.jboss.org/message/908059#908059