Java中怎样取得前一天和下一天的日期？

Question

Calendar.set(Calendar.DAY_OF_YEAR, +1)
Calendar.set(Calendar.DAY_OF_YEAR, -1)

Answer 1

用滚动
Calendar now = Calendar.getInstance();
now.roll(Calendar.DAY_OF_YEAR,1);//明天
now.roll(Calendar.DAY_OF_YEAR,-1);//昨天

Answer 2

java.text.SimpleDateFormat df=new java.text.SimpleDateFormat("yyyy-MM-dd");
  java.util.Calendar calendar=java.util.Calendar.getInstance();
  calendar.roll(java.util.Calendar.DAY_OF_YEAR,-1);
  System.out.println("昨天："+df.format(calendar.getTime()));
  calendar=java.util.Calendar.getInstance();
  System.out.println("今天："+df.format(calendar.getTime()));
  calendar.roll(java.util.Calendar.DAY_OF_YEAR,1);
  System.out.println("明天："+df.format(calendar.getTime()));