Demo1

/**
     * @param length
     * @param start
     *            inclusive.
     * @param end
     *            exclusive.
     * @return
     * @throws NumberWrongException
     */
    public static int[] getRandomInts1(int length, int start, int end) throws NumberWrongException {
        if (length < 2)
            throw new NumberWrongException("The length must be larger than 1.");
        if (start >= end)
            throw new NumberWrongException("start must be smaller than end.");
        int range = end - start;
        if (length > range)
            throw new NumberWrongException("length must be smaller than range.");
        Random random = new Random();
        int[] numbers = new int[length];
        numbers[0] = start + (int) (range * random.nextFloat());
        for (int i = 1; i < length; i++) {
            int temp = start + (int) (range * random.nextFloat());
            int j = 0;
            while (j < i) {
                if (temp == numbers[j]) {
                    temp = start + (int) (range * random.nextFloat());
                    j = 0;
                    continue;
                }
                j++;
            }
            numbers[j] = temp;
        }
        return numbers;
    }
 

Demo2

/**
     * 
     * @param length
     * @param start
     *            inclusive
     * @param end
     *            exclusive
     * @return
     * @throws NumberWrongException
     */
    public static int[] getRandomInts2(int length, int start, int end) throws NumberWrongException {
        if (length < 2)
            throw new NumberWrongException("The length must be larger than 1.");
        if (start >= end)
            throw new NumberWrongException("start must be smaller than end.");
        int range = end - start;
        if (length > range)
            throw new NumberWrongException("length must be smaller than range.");
        Random random = new Random();
        LinkedList<Integer> ll = new LinkedList<Integer>();
        for (int i = start; i < end; i++) {
            ll.add(i);
        }
        int[] numbers = new int[length];
        for (int j = 0; j < length; j++) {
            numbers[j] = ll.remove((int) (random.nextFloat() * ll.size()));
        }
        return numbers;
    }
 

 Demo3 // conbine

    /**
     * @param length
     * @param start
     *            inclusive.
     * @param end
     *            exclusive.
     * @return
     * @throws NumberWrongException
     */
    public static int[] getRandomInts(int length, int start, int end) throws NumberWrongException {
        if (length < 2)
            throw new NumberWrongException("The length must be larger than 1.");
        if (start >= end)
            throw new NumberWrongException("start must be smaller than end.");
        int range = end - start;
        if (length > range)
            throw new NumberWrongException("length must be smaller than range.");
        Random random = new Random();
        int[] numbers = new int[length];
        if (length * 2 > range) {
            LinkedList<Integer> ll = new LinkedList<Integer>();
            for (int i = start; i < end; i++) {
                ll.add(i);
            }
            numbers = new int[length];
            for (int j = 0; j < length; j++) {
                numbers[j] = ll.remove((int) (random.nextFloat() * ll.size()));
            }
        } else {
            numbers[0] = start + (int) (range * random.nextFloat());
            for (int i = 1; i < length; i++) {
                int temp = start + (int) (range * random.nextFloat());
                int j = 0;
                while (j < i) {
                    if (temp == numbers[j]) {
                        temp = start + (int) (range * random.nextFloat());
                        j = 0;
                        continue;
                    }
                    j++;
                }
                numbers[j] = temp;
            }
        }
        return numbers;
    }