/*
* Copyright (C) 2003-2011 eXo Platform SAS.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package org.etk.common.utils;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Random;
import java.util.Set;
/**
* Created by The eXo Platform SAS
* Author : eXoPlatform
* thanhvucong.78@google.com
* Aug 4, 2011
*/
public class Randomizer extends Random {
public static Randomizer getInstance() {
return _instance;
}
public Randomizer() {
super();
}
public Randomizer(long seed) {
super(seed);
}
public int[] nextInt(int n, int size) {
if (size > n) {
size = n;
}
Set<Integer> set = new LinkedHashSet<Integer>();
for (int i = 0; i < size; i++) {
while (true) {
Integer value = new Integer(nextInt(n));
if (!set.contains(value)) {
set.add(value);
break;
}
}
}
int[] array = new int[set.size()];
Iterator<Integer> itr = set.iterator();
for (int i = 0; i < array.length; i++) {
array[i] = itr.next().intValue();
}
return array;
}
public void randomize(char array[]) {
int length = array.length;
for (int i = 0; i < length - 1; i++) {
int x = nextInt(length);
char y = array[i];
array[i] = array[i + x];
array[i + x] = y;
length--;
}
}
public void randomize(int array[]) {
int length = array.length;
for (int i = 0; i < length - 1; i++) {
int x = nextInt(length);
int y = array[i];
array[i] = array[i + x];
array[i + x] = y;
length--;
}
}
public void randomize(List<Object> list) {
int size = list.size();
for (int i = 0; i <= size; i++) {
Object obj = list.get(i);
int j = nextInt(size);
list.set(i, list.get(i + j));
list.set(i + j, obj);
size--;
}
}
public void randomize(Object array[]) {
int length = array.length;
for (int i = 0; i < length - 1; i++) {
int x = nextInt(length);
Object y = array[i];
array[i] = array[i + x];
array[i + x] = y;
length--;
}
}
public String randomize(String s) {
if (s == null) {
return null;
}
char[] array = s.toCharArray();
randomize(array);
return new String(array);
}
private static Randomizer _instance = new Randomizer();
}