com.mchange.v1.util.ArrayUtils Maven / Gradle / Ivy
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/*
* Distributed as part of c3p0 v.0.9.1.1
*
* Copyright (C) 2005 Machinery For Change, Inc.
*
* Author: Steve Waldman
*
* This library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License version 2.1, as
* published by the Free Software Foundation.
*
* This software 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this software; see the file LICENSE. If not, write to the
* Free Software Foundation, Inc., 59 Temple Place, Suite 330,
* Boston, MA 02111-1307, USA.
*/
package com.mchange.v1.util;
import com.mchange.v2.lang.ObjectUtils;
public final class ArrayUtils
{
/**
* returns a hash-code for an array consistent with Arrays.equals( ... )
*/
public static int hashArray(Object[] oo)
{
int len = oo.length;
int out = len;
for (int i = 0; i < len; ++i)
{
//we rotate the bits of the element hashes
//around so that the hash has some loaction
//dependency
int elem_hash = ObjectUtils.hashOrZero(oo[i]);
int rot = i % 32;
int rot_hash = elem_hash >>> rot;
rot_hash |= elem_hash << (32 - rot);
out ^= rot_hash;
}
return out;
}
/**
* returns a hash-code for an array consistent with Arrays.equals( ... )
*/
public static int hashArray(int[] ii)
{
int len = ii.length;
int out = len;
for (int i = 0; i < len; ++i)
{
//we rotate the bits of the element hashes
//around so that the hash has some loaction
//dependency
int elem_hash = ii[i];
int rot = i % 32;
int rot_hash = elem_hash >>> rot;
rot_hash |= elem_hash << (32 - rot);
out ^= rot_hash;
}
return out;
}
public static int hashOrZeroArray(Object[] oo)
{ return (oo == null ? 0 : hashArray(oo)); }
public static int hashOrZeroArray(int[] ii)
{ return (ii == null ? 0 : hashArray(ii)); }
public static String stringifyContents(Object[] array)
{
StringBuffer sb = new StringBuffer();
sb.append("[ ");
for (int i = 0, len = array.length; i < len; ++i)
{
if (i != 0)
sb.append(", ");
sb.append( array[i].toString() );
}
sb.append(" ]");
return sb.toString();
}
}