Uma Classe Para Truncar Valores Double

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package objetos;

import java.text.DecimalFormat;

/**
 *
 * @author Admin
 */
public class TruncarValor {
    public static double Truncar(double valor,int qtddec) {
        DecimalFormat df = new DecimalFormat();
        
        df.applyPattern("0."+String.format("%"+(qtddec+1)+"s","").replaceAll(" ","0"));
        String s = df.format(valor);
        s = s.substring(0, s.length()-1).replaceAll(",", ".");
        return Double.parseDouble(s);
    }
    
    public static void main (String[] args) {
        System.out.println(TruncarValor.Truncar(100.129, 2));
    }
}