LocalDate 的使用
import java.util.Calendar;
import java.util.Scanner;
import java.time.LocalDate;
public class Main {
public static void main(String[] args) {
Scanner console = new Scanner(System.in);
int year = console.nextInt();
for(int i=1; i<=12; i++){
System.out.println(year + "年" + i + "月:" +LocalDate.of(year,i,1).lengthOfMonth() + "天");
}
}
}