How to use variable int for meter meter java and jfreechart

I need the variable int pressure to be equal to the dataset so that it shows when this value changes represented in the graph

    package puertocom;

import java.awt.*;   
import javax.swing.JPanel;   
import org.jfree.chart.ChartPanel;   
import org.jfree.chart.JFreeChart;   
import org.jfree.chart.plot.*;   
import org.jfree.data.Range;   
import org.jfree.data.general.DefaultValueDataset;   
import org.jfree.data.general.ValueDataset;   
import org.jfree.ui.ApplicationFrame;   
import org.jfree.ui.RefineryUtilities;   

public class MeterChartDemo1 extends ApplicationFrame   
{   
 int presion = 100;
    /**  
     *   
     */   
    private static final long serialVersionUID = 1L;   
    private static DefaultValueDataset dataset;   

    public MeterChartDemo1(String s)   
    {   
        super(s);   
        JPanel jpanel = createDemoPanel();   
        jpanel.setPreferredSize(new Dimension(500, 270));   
        setContentPane(jpanel);   
    }   

    private static JFreeChart createChart(ValueDataset valuedataset)   
    {   
        MeterPlot meterplot = new MeterPlot(valuedataset);   
        meterplot.setRange(new Range(0.0D, 60D));   
        meterplot.addInterval(new MeterInterval("Normal", new Range(0.0D, 35D), Color.lightGray, new BasicStroke(2.0F), new Color(0, 255, 0, 64)));   
        meterplot.addInterval(new MeterInterval("Warning", new Range(35D, 50D), Color.lightGray, new BasicStroke(2.0F), new Color(255, 255, 0, 64)));   
        meterplot.addInterval(new MeterInterval("Critical", new Range(50D, 60D), Color.lightGray, new BasicStroke(2.0F), new Color(255, 0, 0, 128)));   
        meterplot.setNeedlePaint(Color.darkGray);   
        meterplot.setDialBackgroundPaint(Color.white);   
        meterplot.setDialOutlinePaint(Color.gray);   
        meterplot.setDialShape(DialShape.CHORD);   
        meterplot.setMeterAngle(260);   
        meterplot.setTickLabelsVisible(true);   
        meterplot.setTickLabelFont(new Font("Dialog", 1, 10));   
//        meterplot.setTickLabelPaint(Color.darkGray);   
//        meterplot.setTickSize(5D);   
//        meterplot.setTickPaint(Color.lightGray);   
        meterplot.setTickLabelPaint(Color.darkGray);   
        meterplot.setTickSize(5D);   
        meterplot.setTickPaint(Color.BLACK);   
        meterplot.setValuePaint(Color.black);   
        meterplot.setValueFont(new Font("Dialog", 1, 14));   
        JFreeChart jfreechart = new JFreeChart("Presion Atmosferica", JFreeChart.DEFAULT_TITLE_FONT, meterplot, true);   
        return jfreechart;   
    }   

    public static JPanel createDemoPanel()   
    {   
        dataset = new DefaultValueDataset(23D);   
        JFreeChart jfreechart = createChart(dataset);   
        ChartPanel chartpanel = new ChartPanel(jfreechart);   
        return chartpanel;   
    }   

    public static void main(String args[])   
    {   
        MeterChartDemo1 meterchartdemo1 = new MeterChartDemo1("Meter Chart Demo 1");   
        meterchartdemo1.pack();   
        RefineryUtilities.centerFrameOnScreen(meterchartdemo1);   
        meterchartdemo1.setVisible(true);   
    }   
}