Java application cpu usage

Source code java

package com.javatmz.javaapp.cpu;


import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.event.*;
import java.lang.management.ManagementFactory;
import java.lang.management.OperatingSystemMXBean;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.List;
import javax.swing.*;
public class CPURealTime extends JFrame {
	private static final int D_W = 1000;
	private static final int D_H = 600;
	int x = 0;
	int y = 0;
	int X0=100;
	int Y0=500;
	int maxY=200;
	int maxX=500;
	List<Integer> listValues=new ArrayList<Integer>();
	DrawPanel drawPanel = new DrawPanel();
	public CPURealTime() {
		ActionListener listener = new AbstractAction() {
			public void actionPerformed(ActionEvent e) {
				if (x >= D_W) {
					
					drawPanel.repaint();
				} else {
					
					drawPanel.repaint();
				}
			}
		};
		Timer timer = new Timer(100, listener);
		timer.start();
		add(drawPanel);
		pack();
		setDefaultCloseOperation(EXIT_ON_CLOSE);
		setLocationRelativeTo(null);
		setVisible(true);
	}
	private class DrawPanel extends JPanel {
		protected void paintComponent(Graphics g) {
			super.paintComponent(g);
			
			drawCPUValues(g);
			
			drawAxes(g);
			drawTitle(g);
		}
		private void drawCPUValues(Graphics g) {
			addCPUValues();
			
			for (int i=0;i<listValues.size();i++) {
				Graphics lineValue=g;
				lineValue.fillRect(X0+x+i, Y0-listValues.get(i), 1, listValues.get(i));
				lineValue.setColor(Color.GREEN);
				//System.out.println(" = "+listValues.get(i));
			}
			
			
		}
		
		private void addCPUValues() {
			OperatingSystemMXBean operatingSystemMXBean=ManagementFactory.getOperatingSystemMXBean();
			
			for (Method method : operatingSystemMXBean.getClass().getDeclaredMethods()) {
				method.setAccessible(true);
				if(method.getName().startsWith("get") && Modifier.isPublic(method.getModifiers())){
					Object value;
					try{
						value=method.invoke(operatingSystemMXBean);
						//System.out.println(method.getName()+" = "+value);
					}catch(Exception exception){
						value=maxY;
					}
					if("getSystemCpuLoad".equals(method.getName())){
						listValues.add(((int) (Double.parseDouble(value.toString())*100)));
						if(listValues.size()>=500){
							listValues.remove(0);
						}
					}
				}
			}
			
			
			
		}
		private void drawTitle(Graphics g) {
			Graphics gTitle= g;
			gTitle.setColor(Color.black);
			gTitle.setFont(new Font("TitleStyle", 21, 30));
			gTitle.drawString("CPU Monitoring with Java TMZ", 230, 100);
		}
		private void drawAxes(Graphics g) {
			Graphics gAxeY= g;
			gAxeY.setColor(Color.black);
			gAxeY.drawLine(X0, Y0, X0, Y0-maxY);
			
			Graphics gAxeYUnit= g;
			gAxeYUnit.setColor(Color.black);
			gAxeYUnit.drawString("100%",X0-20, Y0-maxY );
			
			Graphics gAxeX= g;
			gAxeX.setColor(Color.black);
			gAxeY.drawLine(X0, Y0, X0+maxX, Y0);
		}
		public Dimension getPreferredSize() {
			return new Dimension(D_W, D_H);
		}
	}
	public static void main(String[] args) {
		EventQueue.invokeLater(new Runnable() {
			public void run() {
				new CPURealTime();
			}
		});
	}
}