java获取前六季度 java获取上个月

```java
        String s2 = "2020-02-03 ：01:25:36";
        SimpleDateFormat simple = new SimpleDateFormat("yyyy-MM");
        Date date2 = simple.parse(s2);
        Calendar calendar = new GregorianCalendar();
        calendar.setTime(date2);
        calendar.add(calendar.DATE, -1);
        String lastMonth = simple.format(calendar.getTime());//上个月
        System.out.println("上个月的时间是："+lastMonth);