Unique Random ‘N’ digit Number generator

package com.santhosh.random;

import java.util.Random;

import org.apache.commons.lang3.StringUtils;

public class SequenceGenerator {
    private final Random random;

    public SequenceGenerator() {
        random = new Random();
    }

    /**
     * Returns a pseudo-random integer between 0 and n-1.
     *
     * @see Random#nextInt(int)
     */
    public int nextInt(int n) {
        return random.nextInt(n);
    }

    public static void main(String[] args) {
        SequenceGenerator g = new SequenceGenerator();
        String result = StringUtils.leftPad(String.valueOf(g.nextInt(99999)),
                5, '0');
        System.out.println(result);
    }
}