Display JVM heap details using rJava and R

I finished the first full flow that pulls data from the JVM using JMX and dynamically updates a graph in a browser. I use rJava as the layer between R and Java. I code many lines of java, of course, using jdk 8.

realtimeyoungdata <- function(){
  realtimeyoungdataobserver <- .jnew("com/rxjava/jmx/YoungGenPeriodicObserver")
  occupancy <- .jcall(realtimeyoungdataobserver ,"Lcom/rxjava/jmx/YoungGenOccupancy;","getOccupancy")
  used <- occupancy$getUsed()
  max <- occupancy$getMax()
  print(paste("User[", used,"] Max [", max,"]"))
  result <- c(used, max) 

Interface default methods

I am coding feverishly to complete a web interface to the JVM internals like memory, threads etc. This is my first set of default methods in an interface.

I have not read the JLS comparison between this and other inheritance mechanisms but this serves a purpose.

package com.memory.probe;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.AbstractQueue;
import java.util.concurrent.ArrayBlockingQueue;

import javax.management.remote.JMXConnector;
import javax.management.remote.JMXConnectorFactory;
import javax.management.remote.JMXServiceURL;

import org.apache.log4j.Logger;

public interface Probe {
	Logger l = Logger.getLogger("generation.gc");
	AbstractQueue<Long> abq = new ArrayBlockingQueue<Long>(100);

	default void connectJMXRemote(int port){
	      JMXServiceURL url;
	  	try {
	  		url = new JMXServiceURL(
	  		            "service:jmx:rmi:///jndi/rmi://localhost:" + port + "/jmxrmi");
	  		JMXConnector jmxc = JMXConnectorFactory.connect(url, null);
	  		l.debug("Remote JMX connection is successful");
	  	} catch (IOException e) {

	default String getTrace(Throwable t){
		return getStackTrace(t);
    static String getStackTrace(Throwable t){
    	StringWriter sw = new StringWriter();
    	PrintWriter pw = new PrintWriter(sw);
    	return sw.toString();