code: ///////////////////////////////////////////////////////////////////////////////
  // For information as to what this class does, see the Javadoc, below.       //
  // Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,       //
  // 2007, 2008, 2009, 2010, 2014, 2015 by Peter Spirtes, Richard Scheines, Joseph   //
  // Ramsey, and Clark Glymour.                                                //
  //                                                                           //
  // This program is free software; you can redistribute it and/or modify      //
  // it under the terms of the GNU General Public License as published by      //
  // the Free Software Foundation; either version 2 of the License, or         //
  // (at your option) any later version.                                       //
  //                                                                           //
  // This program is distributed in the hope that it will be useful,           //
  // but WITHOUT ANY WARRANTY; without even the implied warranty of            //
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             //
  // GNU General Public License for more details.                              //
  //                                                                           //
  // You should have received a copy of the GNU General Public License         //
  // along with this program; if not, write to the Free Software               //
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA //
  ///////////////////////////////////////////////////////////////////////////////
  
  package edu.cmu.tetrad.util;
  
  import java.text.DecimalFormat;
  import java.text.NumberFormat;
  import java.util.prefs.Preferences;
  
  /**
   * Provides an application-wide "memory" of the number format to be used.
   *
   * @author Joseph Ramsey
   */
  public class NumberFormatUtil {
      private static final NumberFormatUtil INSTANCE = new NumberFormatUtil();
      private NumberFormat nf;
  
      private NumberFormatUtil() {
  
          try {
              nf = new DecimalFormat(Preferences.userRoot().get("numberFormat", "0.0000"));
          } catch (Exception e) {
              nf = new DecimalFormat("0.0000");
          }
  
      }
  
      /**
       * @return Ibid.
       */
      public static NumberFormatUtil getInstance() {
          return INSTANCE;
      }
  
      /**
       * Sets the number format, <code>nf</code>.
       *
       * @param nf Ibid.
       * @throws NullPointerException if nf is null.
       */
      public void setNumberFormat(NumberFormat nf) {
          if (nf == null) {
              throw new NullPointerException();
          }
  
          this.nf = nf;
      }
  
      /**
       * @return Ibid.
       */
      public NumberFormat getNumberFormat() {
          return nf;
      }
  }
  
  
  
  