Get memory and CPU usage

I know I'm late with my answer, but I think this code is interesting. This is an adaptation of "closed" code, and should be revised before aplying directly:

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;
import java.lang.Process;
import java.lang.Runtime;
import java.util.HashMap;

/**
 * SystemStatusReader is a collection of methods to read system status (cpu and memory)
 * 
 * @author Andreu Correa Casablanca
 */
public class SystemStatusReader
{
    public static final int CONSERVATIVE    = 0;
    public static final int AVERAGE     = 1;
    public static final int OPTIMISTIC  = 2;

    /**
     * cpuUsage gives us the percentage of cpu usage
     * 
     * mpstat -P ALL out stream example:
     *
     *  Linux 3.2.0-30-generic (castarco-laptop)    10/09/12    _x86_64_    (2 CPU)                 - To discard
     *                                                                                              - To discard
     *  00:16:30     CPU    %usr   %nice    %sys %iowait    %irq   %soft  %steal  %guest   %idle    - To discard
     *  00:16:30     all   17,62    0,03    3,55    0,84    0,00    0,03    0,00    0,00   77,93
     *  00:16:30       0   17,36    0,05    3,61    0,83    0,00    0,05    0,00    0,00   78,12
     *  00:16:30       1   17,88    0,02    3,49    0,86    0,00    0,01    0,00    0,00   77,74
     * 
     * @param measureMode Indicates if we want optimistic, convervative or average measurements.
     */
    public static Double cpuUsage (int measureMode) throws Exception {

        BufferedReader mpstatReader = null;

        String      mpstatLine;
        String[]    mpstatChunkedLine;

        Double      selected_idle;

        try {
            Runtime runtime = Runtime.getRuntime();
            Process mpstatProcess = runtime.exec("mpstat -P ALL");

            mpstatReader = new BufferedReader(new InputStreamReader(mpstatProcess.getInputStream()));

            // We di