AfflictionNetworks/samskivert
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Added reverse(int[]).

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git-svn-id: https://samskivert.googlecode.com/svn/trunk@796 6335cc39-0255-0410-8fd6-9bcaacd3b74c
This commit is contained in:
shaper
2002-07-11 01:33:54 +00:00
parent 1bbaf04fa9
commit c575c5b2b2
1 changed files with 62 additions and 3 deletions
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projects/samskivert/src/java/com/samskivert/util/ArrayUtil.java
+62 -3
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@@ -1,5 +1,5 @@
//
// $Id: ArrayUtil.java,v 1.5 2002/05/29 18:00:04 ray Exp $
// $Id: ArrayUtil.java,v 1.6 2002/07/11 01:33:54 shaper Exp $
//
// samskivert library - useful routines for java programs
// Copyright (C) 2001 Walter Korman
@@ -29,6 +29,36 @@ import com.samskivert.Log;
*/
public class ArrayUtil
{
/**
* Reverses the elements in the given array.
*
* @param values the array to reverse.
*/
public static void reverse (int[] values)
{
reverse(values, 0, values.length);
}
/**
* Reverses a subset of elements within the specified array.
*
* @param values the array containing elements to reverse.
* @param offset the index at which to start reversing elements.
* @param length the number of elements to reverse.
*/
public static void reverse (int[] values, int offset, int length)
{
int aidx = offset;
int bidx = offset + length - 1;
while (bidx > aidx) {
int value = values[aidx];
values[aidx] = values[bidx];
values[bidx] = value;
aidx++;
bidx--;
}
}
/**
* Shuffles the elements in the given array into a random sequence.
*
@@ -124,9 +154,38 @@ public class ArrayUtil
public static void main (String[] args)
{
// test shuffling two elements
int[] values = new int[] { 0, 1 };
// test reversing an array
int[] values = new int[] { 0 };
int[] work = (int[])values.clone();
reverse(work);
Log.info("reverse: " + StringUtil.toString(work));
values = new int[] { 0, 1, 2 };
work = (int[])values.clone();
reverse(work);
Log.info("reverse: " + StringUtil.toString(work));
work = (int[])values.clone();
reverse(work, 0, 2);
Log.info("reverse first-half: " + StringUtil.toString(work));
work = (int[])values.clone();
reverse(work, 1, 2);
Log.info("reverse second-half: " + StringUtil.toString(work));
values = new int[] { 0, 1, 2, 3, 4 };
work = (int[])values.clone();
reverse(work, 1, 3);
Log.info("reverse middle: " + StringUtil.toString(work));
values = new int[] { 0, 1, 2, 3 };
work = (int[])values.clone();
reverse(work);
Log.info("reverse even: " + StringUtil.toString(work));
// test shuffling two elements
values = new int[] { 0, 1 };
work = (int[])values.clone();
shuffle(work, 0, 1);
Log.info("first-half shuffle: " + StringUtil.toString(work));