Here is an experiment with javap to extract the methods programatically. It looks like javassit will be a better way to do this (specially since it is native)

javap-test.java

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

/**
 * Created by diniscruz on 01/09/2016.
 */
public class JavapHelper {

    public static String pathToClass(Class clazz)
    {
        return clazz.getResource("/" + clazz.getName().replace(".","/") + ".class").toString();
    }

    public static String decompileClass(Class clazz) {
        String path = pathToClass(clazz);
        System.out.println(path);
        String[] args = new String[] {"-v", path};
        StringWriter stringWriter = new StringWriter();
        PrintWriter printWriter = new PrintWriter(stringWriter);
        com.sun.tools.javap.Main.run(args, printWriter);
        printWriter.close();
        return stringWriter.toString();
    }

    public static HashMap<String,List<String>> constantPool(Class clazz)
    {
        String rawData  = decompileClass(clazz);
        String[] lines = rawData.split("\n");

        HashMap<String,List<String>> results = new HashMap<String,List<String>>();

        boolean insideConstantPool = false;
        for (String line :lines) {
            if(line.equals("Constant pool:"))           // start of Constant pool data
            {
                System.out.println(line);
                insideConstantPool = true;
                continue;
            }
            if(insideConstantPool)
            {
                //System.out.println("> " + line);
                if (line.equals("{"))
                    break;

                String[] data = line.split("=",2)               // extract the data to the right of the first =
                                    [1].trim()                  // [0] is the id [1] is the rest of the line
                                    .split(" ", 2);             // split the constant pool name and its value
                if (data.length == 2) {
                    String key = data[0];                        // constant pool name
                    String value = data[1];                        // constant pool value
                    if (!results.containsKey(key))                   // if it is the first time we see this key
                        results.put(key, new ArrayList<>());
                    results.get(key).add(value.trim());             // add key's value to key's list<String>
                }

            }
            //System.out.print(line == "Constant pool:");
            //System.out.println("  - " + line);
        }
        //System.out.println(lines);
        //3System.out.println(lines.length);
        return results;
    }
}

    
    
    @Test
    public void constantPool() throws Exception {

        Context context = new Context();
        String pathToClass =  JavapHelper.pathToClass(JavapHelper.class);

        JavapTask javapTask = new JavapTask();
        StringWriter stringWriter = new StringWriter();
        PrintWriter printWriter = new PrintWriter(stringWriter);
        javapTask.setLog(printWriter);

        //Object methods = javapTask.getClass().getMethods();
        //Object declared_methods = javapTask.getClass().getDeclaredMethods();

        //JavapHelper.constantPool(JavapHelper.class);

        Method method_Open = javapTask.getClass().getDeclaredMethod("open", String.class);
        Method method_Run  = javapTask.getClass().getDeclaredMethod("run", String[].class);
        method_Open.setAccessible(true);
        method_Run.setAccessible(true);

        String[] args = new String[] {"-v", pathToClass};




        method_Run.invoke(javapTask,new Object[] { args });

        System.out.println(stringWriter.toString());
        System.out.println("Done");

        JavaFileObject openData = (JavaFileObject)method_Open.invoke(javapTask, new Object[] { pathToClass });
        JavapTask.ClassFileInfo classFileInfo = javapTask.read(openData);
        //System.out.println(openData);
        //System.out.println(classFileInfo);

        ConstantPool constantPool = classFileInfo.cf.constant_pool;
        for (ConstantPool.CPInfo entry : constantPool.entries())
        {
            if(entry instanceof com.sun.tools.classfile.ConstantPool.CONSTANT_Methodref_info)
            {
                ConstantPool.CONSTANT_NameAndType_info nameAndType = ((ConstantPool.CONSTANT_Methodref_info)entry).getNameAndTypeInfo();
                System.out.println(String.format("%s.%s", nameAndType.getType(), nameAndType.getName()));
            }
        }
        //((com.sun.tools.classfile.ConstantPool.CONSTANT_Methodref_info)classFileInfo.cf.constant_pool.get(8)).getNameAndTypeInfo().getType()

  }