Formatting Source Code programmatically with JDT

Question

I am generating some classes with JDT. Afterwards I would like to format the whole ICompilationUnit, just as if I pressed Ctrl+Shift+F (Source > Format) in an open Editor wi

Answer 1

I use the following method to format a Java Source file

    public static void formatSource(ICompilationUnit cu, IProgressMonitor progressMonitor) throws JavaModelException{
    String source = cu.getSource();
    IJavaProject javaProject = cu.getJavaProject();

    Map options = javaProject.getOptions(true);


            // Instantiate the default code formatter with the given options
            final CodeFormatter codeFormatter = ToolFactory.createCodeFormatter(options);


            final TextEdit edit = codeFormatter.format(
                CodeFormatter.K_COMPILATION_UNIT, // format a compilation unit
                source, // source to format
                0, // starting position
                source.length(), // length
                0, // initial indentation
                System.getProperty("line.separator") // line separator
            );          

            cu.becomeWorkingCopy(progressMonitor);
            try {
                cu.applyTextEdit(edit, progressMonitor);
                //cu.reconcile();
                cu.commitWorkingCopy(true, progressMonitor);
                //cu.save(progressMonitor, false);

                JavaUI.openInEditor(cu);


            } catch (MalformedTreeException e) {
                e.printStackTrace();
            } catch (PartInitException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }   

}

Answer 2

This could be a bug, but using the JDK in Elcipse 4.2.2, it is necessary to create a working copy of the ICompilationUnit in order to apply a TextEdit to the file.

    targetUnit.becomeWorkingCopy(new SubProgressMonitor(monitor, 1));
    ... do work on the source file ...
    formatUnitSourceCode(targetUnit, new SubProgressMonitor(monitor, 1));
    targetUnit.commitWorkingCopy(true, new SubProgressMonitor(monitor, 1));

The formatting itself is done like this:

public static void formatUnitSourceCode(ICompilationUnit unit, IProgressMonitor monitor) throws JavaModelException {
    CodeFormatter formatter = ToolFactory.createCodeFormatter(null);
    ISourceRange range = unit.getSourceRange();
    TextEdit formatEdit = formatter.format(CodeFormatter.K_COMPILATION_UNIT, unit.getSource(), range.getOffset(), range.getLength(), 0, null);
    if (formatEdit != null && formatEdit.hasChildren()) {
        unit.applyTextEdit(formatEdit, monitor);
    } else {
        monitor.done();
    }
}

Answer 3

When generating some classes by using JDT, you can put "\t"s in your source code. Or like what you did, using code formatter. I have tested the following code:

public static void main(String[] args)
{
    String code = "public class TestFormatter{public static void main(String[] args){System.out.println(\"Hello World\");}}";
    CodeFormatter codeFormatter = ToolFactory.createCodeFormatter(null);

    TextEdit textEdit = codeFormatter.format(CodeFormatter.K_UNKNOWN, code, 0,code.length(),0,null);
    IDocument doc = new Document(code);
    try {
        textEdit.apply(doc);
        System.out.println(doc.get());
    } catch (MalformedTreeException e) {
        e.printStackTrace();
    } catch (BadLocationException e) {
        e.printStackTrace();
    }   
}

The apply() method does the trick here.