How to find total CPU utilisation in java using Sigar

I am trying to find a few system statistics (CPU Utilisation%, Disk Utilisation% and Memory Utilisation%) through a Java program. For this purpose I have been using SIGAR. Although (I think) I am getting the latter two correct, I am not getting the CPU Utilisation% correct. Appending my code below, can someone help me understand what is going wrong here?

import java.io.*;
import java.util.*;
import java.text.*;
import java.lang.*;

import org.hyperic.sigar.CpuTimer;
import org.hyperic.sigar.DiskUsage;
import org.hyperic.sigar.FileSystemUsage;
import org.hyperic.sigar.Mem;
import org.hyperic.sigar.Sigar;
import org.hyperic.sigar.SigarException;




public class SystemMonitor {

    private static Sigar sigar = new Sigar();

    public static void getSystemStatistics(){
        Mem mem = null;
        CpuTimer cputimer = null;
        FileSystemUsage filesystemusage = null;
        try {
            mem = sigar.getMem();
            cputimer = new CpuTimer(sigar);
            filesystemusage = sigar.getFileSystemUsage("C:");          
        } catch (SigarException se) {
            se.printStackTrace();
        }


        System.out.print(mem.getUsedPercent()+"\t");
        System.out.print(cputimer.getCpuUsage()+"\t");
        System.out.print(filesystemusage.getUsePercent()+"\n");

    }

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        SystemMonitor m1 = new SystemMonitor();
        for(int i=0; i<1000;i++){
        m1.getSystemStatistics();   
        }
    }




}

I am getting a CPUUtilisation % of 0 consistently, which I think is incorrect.

I was interpreting CpuTimer incorrectly. I could find the CPU utilisation by using CpuPerc instead. Appending the code snippet:

public static void getSystemStatistics(){
    Mem mem = null;
    CpuPerc cpuperc = null;
    FileSystemUsage filesystemusage = null;
    try {
        mem = sigar.getMem();
        cpuperc = sigar.getCpuPerc();
        filesystemusage = sigar.getFileSystemUsage("C:");          
    } catch (SigarException se) {
        se.printStackTrace();
    }


    System.out.print(mem.getUsedPercent()+"\t");
    System.out.print((cpuperc.getCombined()*100)+"\t");
    System.out.print(filesystemusage.getUsePercent()+"\n");
}