Java计算一组数据百分位的值

	
	public static String getPercentile(double[] array, double percentile, int digit) {
		if (array == null || array.length == 0) {
			return null;
		}
		if (array.length == 1) {
			return new BigDecimal(String.valueOf(array[0])).setScale(digit, BigDecimal.ROUND_HALF_EVEN).stripTrailingZeros().toPlainString();
		}
        Arrays.sort(array);
        BigDecimal x = new BigDecimal(array.length - 1).multiply(new BigDecimal(String.valueOf(percentile)));
        int i = x.intValue();
        BigDecimal j = x.subtract(new BigDecimal(i));
        BigDecimal r = (new BigDecimal(1).subtract(j)).multiply(new BigDecimal(String.valueOf(array[i]))).add(j.multiply(new BigDecimal(String.valueOf(array[i + 1]))));
        return r.setScale(digit, BigDecimal.ROUND_HALF_EVEN).stripTrailingZeros().toPlainString();
    }