这句Java，为什么会报这个错？

Question

Calendar.getInstance().add(Calendar.DATE, -1).getTime();
报这个错：
Cannot invoke getTime() on the primitive type void

Answer 1

Calendar cal = Calendar.getInstance();
cal.setTime(new Date());
cal.add(Calendar.DATE, -1);
long time = cal.getTime();

Just write it like this.

Answer 2

Look at the documentation, add() 的返回类型是 void，怎么可能会有 getTime() method

Answer 3

Calendar.getInstance().add(Calendar.DATE, -1)This sentence returns void

Answer 4

Builder mode needs to be written by yourself