代码：

/**
     * 获取前一天的日期
     *
     * @param newFormat 当前日期
     * @return
     */
    public static String previousDate(String newFormat) {
        String s = null;
        try {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy.MM.dd");
            Date day = sdf.parse(newFormat);
            long ms = day.getTime() - 1 * 24 * 3600 * 1000L;
            Date prevDay = new Date(ms);
            s = sdf.format(prevDay);
            System.out.println(s);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return s;
    }