How I can indent generated java code java?

Question

I work in a small learning program that generates Java code from a picture. I hold my code in a StringBuilder. I wonder as I can give the text a normal Java code indentation. I could use some library, but not to format the source code, but the String that has generated Java code. Thanks for your attention.

Answer 1

How about the following code:

import java.io.ByteArrayInputStream;

import com.github.javaparser.JavaParser;
import com.github.javaparser.ParseException;
import com.github.javaparser.ast.CompilationUnit;

public static void main(String[] args) throws ParseException {
        String java = new String("public class ThisIsANonWellFormattedJavaClass {public static void main(String[] args){}}");
        CompilationUnit cu = JavaParser.parse(new ByteArrayInputStream(java.getBytes()));
        System.out.println(cu.toString());
    }

It uses a great Java parser library called javaparser