prints some builder code into the console

BuilderGeneratorPrinter

import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.text.MessageFormat;
import java.util.Collection;

public class BuilderGeneratorPrinter
{
    public static void printBuilderForClass (final String internalObjectName, final Class<?> classToCreateBuilderFor)
    {
        final String header = "public static class Builder {";
        System.out.println(header);

        final String isFinalizedDeclaration = " private boolean finalized = false;";
        System.out.println(isFinalizedDeclaration);

        final String classSimpleName = classToCreateBuilderFor.getSimpleName();

        System.out.println("private " + classSimpleName + " " + internalObjectName + ";");

        final StringBuilder create = new StringBuilder();
        create.append("public static Builder create()");
        create.append("{");
        create.append("return new Builder();");
        create.append("}");
        System.out.println(create.toString());

        final StringBuilder constructor = new StringBuilder();
        constructor.append("private Builder()");
        constructor.append("{");

        constructor.append(internalObjectName + " = " + " new " + classSimpleName + "();");
        constructor.append("}");
        System.out.println(constructor);

        final Field[] fields = classToCreateBuilderFor.getDeclaredFields();
        for (final Field field : fields)
        {
            System.out.println(generateWith(internalObjectName, field));
        }
        final StringBuilder vnfs = new StringBuilder();
        vnfs.append("private void verifyNotFinalizedState() {");
        vnfs.append("\t if(finalized) {");
        vnfs.append("\t\t throw new IllegalStateException(\"This builder is finalized and cannot be modified further\");");
        vnfs.append("\t}");
        vnfs.append("}");
        System.out.println(vnfs.toString());

        final StringBuilder build = new StringBuilder();
        build.append("public " + classSimpleName + " build() {");
        build.append(" if (!finalized)");
        build.append("\t{");
        build.append("\t\t finalized = true;");
        build.append("\t}");
        build.append(" return " + internalObjectName + ";");
        build.append("}");
        System.out.println(build.toString());
        System.out.println("}");
    }

    private static String generateWith (final String internalItem, final Field field)
    {
        final String fieldName = field.getName();
        final Class<?> fieldType = field.getType();

        final String methodNameTemplate = "{0}{1}";
        final String propertyNameFirstCap = Character.toUpperCase(fieldName.charAt(0)) + fieldName.substring(1);
        String methodName = MessageFormat.format(methodNameTemplate, "with", propertyNameFirstCap);

        String argType = fieldType.getSimpleName();

        String returnType = argType;
        String argName = field.getName();
        String assignmentLine = internalItem + "." + fieldName + " = " + fieldName + ";";
        if (Collection.class.isAssignableFrom(fieldType))
        {
            final Type genericType = field.getGenericType();
            final ParameterizedType paramType = (ParameterizedType) genericType;
            final Type firstArg = paramType.getActualTypeArguments()[0];
            final Class firstArgClass = (Class) firstArg;
            final String firstArgName = firstArgClass.getSimpleName();
            returnType = returnType + "<" + firstArgName + ">";
            final String noS = propertyNameFirstCap.substring(0, propertyNameFirstCap.length() - 1);
            methodName = MessageFormat.format(methodNameTemplate, "add", noS);
            argType = firstArgName;
            argName = noS;
            assignmentLine = internalItem + "." + fieldName + ".add(" + argName + ");";
        }

        final StringBuilder withMethodBuilder = new StringBuilder();
        withMethodBuilder.append("public Builder " + methodName + "(final " + argType + " " + argName + ")");
        withMethodBuilder.append("{");
        withMethodBuilder.append("verifyNotFinalizedState();");
        withMethodBuilder.append(assignmentLine);
        withMethodBuilder.append(" return this;");
        withMethodBuilder.append("}");

        return withMethodBuilder.toString();
    }

}