code: // from gee.cs.oswego.edu/home/jsr166/jsr166
  
  package jsr166tests.jtreg.util.TimSort;
  
  /*
   * Copyright 2009 Google Inc.  All Rights Reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.
   *
   * This code 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
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
   * CA 95054 USA or visit www.sun.com if you need additional information or
   * have any questions.
   */
  
  import java.util.Random;
  import java.math.BigInteger;
  
  public enum ArrayBuilder {
  
      // These seven are from  Tim's paper (listsort.txt)
  
      RANDOM_INT {
          public Object[] build(int len) {
              Integer[] result = new Integer[len];
              for (int i = 0; i < len; i++)
                  result[i] = rnd.nextInt();
              return result;
          }
      },
  
      DESCENDING_INT {
          public Object[] build(int len) {
              Integer[] result = new Integer[len];
              for (int i = 0; i < len; i++)
                  result[i] = len - i;
              return result;
          }
      },
  
      ASCENDING_INT {
          public Object[] build(int len) {
              Integer[] result = new Integer[len];
              for (int i = 0; i < len; i++)
                  result[i] = i;
              return result;
          }
      },
  
      ASCENDING_3_RND_EXCH_INT {
          public Object[] build(int len) {
              Integer[] result = new Integer[len];
              for (int i = 0; i < len; i++)
                  result[i] = i;
              for (int i = 0; i < 3; i++)
                  swap(result, rnd.nextInt(result.length),
                               rnd.nextInt(result.length));
              return result;
          }
      },
  
      ASCENDING_10_RND_AT_END_INT {
          public Object[] build(int len) {
              Integer[] result = new Integer[len];
              int endStart = len - 10;
              for (int i = 0; i < endStart; i++)
                  result[i] = i;
              for (int i = endStart; i < len; i++)
                  result[i] = rnd.nextInt(endStart + 10);
              return result;
          }
      },
  
      ALL_EQUAL_INT {
          public Object[] build(int len) {
              Integer[] result = new Integer[len];
              for (int i = 0; i < len; i++)
                  result[i] = 666;
              return result;
          }
      },
  
      DUPS_GALORE_INT {
          public Object[] build(int len) {
              Integer[] result = new Integer[len];
              for (int i = 0; i < len; i++)
                  result[i] = rnd.nextInt(4);
              return result;
          }
      },
  
      RANDOM_WITH_DUPS_INT {
          public Object[] build(int len) {
              Integer[] result = new Integer[len];
              for (int i = 0; i < len; i++)
                  result[i] = rnd.nextInt(len);
              return result;
          }
      },
  
      PSEUDO_ASCENDING_STRING {
          public String[] build(int len) {
              String[] result = new String[len];
              for (int i = 0; i < len; i++)
                  result[i] = Integer.toString(i);
              return result;
          }
      },
  
      RANDOM_BIGINT {
          public BigInteger[] build(int len) {
              BigInteger[] result = new BigInteger[len];
              for (int i = 0; i < len; i++)
                  result[i] = HUGE.add(BigInteger.valueOf(rnd.nextInt(len)));
              return result;
          }
      };
  
      public abstract Object[] build(int len);
  
      public void resetRandom() {
          rnd = new Random(666);
      }
  
      private static Random rnd = new Random(666);
  
      private static void swap(Object[] a, int i, int j) {
          Object t = a[i];
          a[i] = a[j];
          a[j] = t;
      }
  
      private static BigInteger HUGE = BigInteger.ONE.shiftLeft(100);
  }
  