public static class XxxDto {
  public static String a_PROCEDURE_PARAMETER = "return";
  public static String c_PROCEDURE_PARAMETER = "inout";
  public static String b_PROCEDURE_PARAMETER = "in";

  private double a;
  private double c;
  private double b;
  //...
}

a
c
b

b
c
a

package org.seasar.dao.impl;
public class ProcedureMetaDataFactoryImpl implements ProcedureMetaDataFactory {
public ProcedureMetaData createProcedureMetaData(
            final String procedureName, final Method method) {
        final ProcedureMetaDataImpl metaData = new ProcedureMetaDataImpl(
                procedureName);
        final Class dtoClass = getParameterType(method);
        // ...
        // Class#getDeclaredFields() は順序保証しない
        final Field[] fields = dtoClass.getDeclaredFields();
        // ...
    }
}