I was wondering if I could use the Eclipse Code Formatter from inside my code … so, the logical thing to do was to ask on stackoverflow, and see if anyone knew how to do that. Thanks to VonC‘s answer, I found out about the CodeFormatter class … and 10 jars and 2 hours later, I’ve got it working.
Here’s how I did it.
CodeFormatter is an abstract class, which means you can’t instantiate it directly. So, I started to search about classes derived from it, and so I found out about DefaultCodeFormatter, which I presumed was what I was looking for. I was right.
DefaultCodeFormatter implements the method :
public abstract TextEdit format(int kind,
String source,
int offset,
int length,
int indentationLevel,
String lineSeparator)
Method documentation can be read here.
I wrote the following code to test it :
... main(String[] args) {
String code = "public class geo{public static void main(String[] args){System.out.println(\"geo\");}}";
CodeFormatter cf = new DefaultCodeFormatter();
TextEdit te = cf.format(CodeFormatter.K_UNKNOWN, code, 0,code.length(),0,null);
System.out.println(te);
}
I used the CodeFormatter.K_UNKNOWN constant for the formatting, because I was thinking that the CodeFormatter will “deduce” the type of code I’ve passed it. I’m not really sure what K_UNKNOWN does, but it seems to work well with the code I’ve tried.
So … the DefaultCodeFormatter returned a TextEdit object as the result of the code formatting.
I was kind of hoping that it’s toString method would give me the code. Instead, I found out it had several ReplaceEdit children nodes. I tried to iterate over each of the children and print their text using their getText, but they wouldn’t “show me the code” 🙂 . I thought “TextEdit’s apply method sounds interesting. Let’s see what it does”. Checking it’s method signature :
apply(IDocument document) revealed a IDocument parameter. I was hoping it would be easy to create a Document object, and that I wouldn’t need any other “eclipse objects”. Turns out it was easy. There is a Document implementation, that has a String constructor :
Document(String initialContent)I applied the TextEdit to the document, and hoped for the best. The eclipse console printed out nicely formatted code. WIN !
Here’s the full code for the class I used to test the CodeFormatter :
import org.eclipse.jdt.core.formatter.CodeFormatter;
import org.eclipse.jdt.internal.formatter.DefaultCodeFormatter;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.Document;
import org.eclipse.jface.text.IDocument;
import org.eclipse.text.edits.MalformedTreeException;
import org.eclipse.text.edits.MultiTextEdit;
import org.eclipse.text.edits.ReplaceEdit;
import org.eclipse.text.edits.TextEdit;
public class FormatterTest {
public static void main(String[] args)
{
String code = "public class geo{public static void main(String[] args){System.out.println(\"geo\");}}";
CodeFormatter cf = new DefaultCodeFormatter();
TextEdit te = cf.format(CodeFormatter.K_UNKNOWN, code, 0,code.length(),0,null);
IDocument dc = new Document(code);
try {
te.apply(dc);
System.out.println(dc.get());
} catch (MalformedTreeException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (BadLocationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
Here’s the list of jars I had to add to the classpath to get the code formatter to work :
They may have different versions on your eclipse installation. They worked for my eclipse installation :
Version: 3.4.2
Build id: M20090211-1700
One of those jars isn’t needed, but I can’t remember which. Sorry for the extra classes.
Hope this helps anyone!
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