Sunday, February 22, 2015

Reformatting multiple source files

Recently I had to apply a new code formatter template to a project. Changing 50+ files by hand seemed to be too much monkey work. Writing a custom plug-in seemed to be too much work. Fortunately there is this great scripting framework to accomplish this task quite easily.

Step 1: Detecting affected source files

I have already blogged about EASE and how to install it. So I went directly to the script shell to fetch all java files form a certan project:

files = findFiles("*.java", getProject("org.eclipse.some.dedicated.project"), true)
Now we have an array of IFile instances. Easy, isn't it?

Step 2: The formatter script

Ideas how to format source files can be found in the forum. Taking the script and porting it to JS is simple:
function formatUnitSourceCode(file) {
 unit = org.eclipse.jdt.core.JavaCore.create(file);


 formatter = org.eclipse.jdt.core.ToolFactory.createCodeFormatter(null);
 range = unit.getSourceRange();
 formatEdit = formatter
       | org.eclipse.jdt.core.formatter.CodeFormatter.F_INCLUDE_COMMENTS,
     unit.getSource(), 0, unit.getSource().length(), 0, null);
 if (formatEdit.hasChildren()) {
  unit.applyTextEdit(formatEdit, null);
  unit.reconcile(org.eclipse.jdt.core.dom.AST.JLS4, false, null, null);

 unit.commitWorkingCopy(true, null);

Step 3: glueing it all together

Load the function into your script shell, fetch the list of files as in step 1 and then process all files in a loop:
for each (file in files) formatUnitSourceCode(file);
That's it. This short script uses your current source formatter settings and applies it to all selected files.

This little helper is available online in the EASE script repository.


  1. Nice!
    Although, you can right-click a project in Eclipse and do Source>Format, right?