获取任一月份的天数

public class Demo2 {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入年份：");
        int year = sc.nextInt();

        Calendar instance = Calendar.getInstance();
        instance.set(year,5,1);
        instance.add(Calendar.DATE,-1);
        System.out.println(instance.get(Calendar.DATE));
    }
}