Code tool class to get various random numbers

Package com.lyt.base.util;


Import Java.text.DateFormat;
Import Java.text.SimpleDateFormat;
Import java.util.ArrayList;
Import Java.util.Date;
Import Java.util.HashMap;
Import java.util.List;
Import Java.util.Map;
Import Java.util.Random;


public class Randomutil {
/**
* Generate an N-bit random number string
*
* @param n
* @return
*/
public static String getrandomnum (int length) {
String str = "0123456789";
Random random = new random ();
StringBuffer sb = new StringBuffer ();


for (int i = 0; i < length; ++i) {
int number = Random.nextint (9);//[1,9]
Sb.append (Str.charat (number+1));
}
return sb.tostring ();
}


/**
* Generate a random n-bit string
*
* @param length
* @return
*/
public static String getrandomstring (int length) {
String str = "abcdefghijklmnopqrstuvwxyz0123456789";
Random random = new random ();
StringBuffer sb = new StringBuffer ();


for (int i = 0; i < length; ++i) {
int number = Random.nextint (36);//[0,36]
Sb.append (Str.charat (number));
}
return sb.tostring ();
}


/**
* Get current time, Month date
*
* @return
*/
public static String GetDate () {
String str = "";
DateFormat df = new SimpleDateFormat ("YYYYMMDDHH");
Date date = new Date ();
str = Df.format (date);
return str;
}


/**
* Generate user id,10 bit, pure digital
*
* @return
*/
public static String UserId () {
String userId = "";
UserId = Getrandomnum (10);
return userId;
}


/**
* Generate order number, 13-bit, pure digital
*
* @return
*/
public static String OrderId () {
String orderId = "";
String date = GetDate ();
String rand = getrandomnum (13);
OrderId = date + Rand;
return orderId;
}


/**
* Generate product id,10 bit, pure digital
*
* @return
*/
public static String proid () {
String userId = "";
UserId = Getrandomnum (10);
return userId;
}

/**
* Random Fetch list data
* @param list
* @param N to take a few
* @return
*/
@SuppressWarnings ({"Rawtypes", "unused", "unchecked"})
public static list getrandomlist (list list, int n) {
Map map = new HashMap ();
List listnew = new ArrayList ();
if (List.size () <=n) {
return list;
}else{
while (Map.size () <n) {
int random = (int) (Math.random () * list.size ());
if (!map.containskey (random)) {
Map.put (Random, "");
Listnew.add (List.get (random));
}
}
return listnew;
}
}


/**
* Take array random number
* @param arr
* @param n
* @return
*/
@SuppressWarnings ({"Unused", "unchecked"})
public static long[] Createrandomarray (long[] arr, int n) {
TODO auto-generated Method Stub
@SuppressWarnings ("Rawtypes")
Map map = new HashMap ();
long[] arrnew = new Long[n];
if (arr.length<=n) {
return arr;
}else{
int count = 0;//new array subscript count
while (Map.size () <n) {
int random = (int) (Math.random () * arr.length);
if (!map.containskey (random)) {
Map.put (Random, "");
arrnew[count++] = Arr[random];
}
}
return arrnew;
}
}

}