Question

Java编程中，程序不走部分if语句

public static void main(String[] args) {
int year,month,day,week; //
Scanner input = new Scanner(System.in);
System.out.print("年月日：");
year = input.nextInt();
month = input.nextInt();
day = input.nextInt();
week = 8;
if(year < 2015 && year > 2015){
System.out.print("输入不合法.");
}else if (year == 2015&&month ==10){
week = (day + 3) % 7;
}else if (year == 2015&&month == 11){
week = (day + 6)%7;
}else if (year == 2015&&month == 12){
week =(day + 1)% 7;
}else if (year ==2016&&month == 1){
week = 5;
}
System.out.printf("星期%d.\n",week);

为什么程序不经过if(year < 2015 && year > 2015){
System.out.print("输入不合法.");

Answer 1

if(year < 2015 && year > 2015){

改成：
if(year < 2015 || year > 2015){

或
if(year != 2015 ){

后面的else中 year==2015都是多余的，可以删除掉

追问

大神再问一个问题，按你方法改了
然后run显示
年月日：2014 5 19
输入不合法.星期8.
怎么把星期8去掉？？

追答

     week = 8;
       if(year < 2015 && year > 2015){
           System.out.print("输入不合法.");
       }else { //把输出放到另一个分支中就好了
           if (month ==10){
           week = (day + 3) % 7;       
           }else if (month == 11){
               week = (day + 6)%7;    
            }else if (month == 12){
                week =(day + 1)% 7;
            }else { //??
                week = 5;
            }
            System.out.printf("星期%d.\n",week);
        }

Answer 2

请问，year可不可能同时大于2015又小于2015