求救哇。This method must return a result of type String

[wsyccc0725]

import java.util.Scanner;
public class LeapYear{
public static void main(String[] args){
System.out.println("Please enter a year greater than 1582.");
Scanner scan=new Scanner(System.in);
int year=scan.nextInt();
int month=2,day=29;
if(year>=1582){
if(isLeapYear(year)){
System.out.println(year+" is leap year");
Zellers(year,month,day);
}
else{
System.out.println(year+" is not leap year");
}
}
else{
System.out.println("The year that entered is out of range.");
}
}
public static boolean isLeapYear(int year){
if (year%4==0 && year%100!=0){
return true;
}
else{
if (year%400==0)
return true;
}
return false;
}
public static void Zellers(int year,int month,int day){
int LeapFactor,DayNumber,StartMonth,StartYear;
StartMonth=0;
StartYear=year-1;
LeapFactor =(StartYear/4)-(StartYear/100)+(StartYear/400);
DayNumber=((365*year+31*(month-1)+day+LeapFactor-StartMonth)-1);
System.out.println(DisplayDay(DayNumber)+ " was Feb 29th in "+year);
}
public static String DisplayDay(int DayNumber){
switch (DayNumber)
{
case 0:
return "Sunday";
case 1:
return "Monday";
case 2:
return "Tuesday";
case 3:
return "Wednesday";
case 4:
return "Thursday";
case 5:
return "Friday";
case 6:
return "Saturday";
}
}
}

新手刚刚学习java

[wingson_shen]

public static String DisplayDay(int DayNumber){
switch (DayNumber)
{
case 0:
return "Sunday";
case 1:
return "Monday";
case 2:
return "Tuesday";
case 3:
return "Wednesday";
case 4:
return "Thursday";
case 5:
return "Friday";
case 6:
return "Saturday";
}
return "";//总得有个返回值的。如果DayNumber小于0大于6而不进这个语句呢。
}

[菖蒲老先生]

	public static String DisplayDay(int DayNumber) {
		switch (DayNumber) {
		case 0:
			return "Sunday";
		case 1:
			return "Monday";
		case 2:
			return "Tuesday";
		case 3:
			return "Wednesday";
		case 4:
			return "Thursday";
		case 5:
			return "Friday";
		case 6:
			return "Saturday";
		default:
			return "";
		}
	}

[LoongMint]

public static String DisplayDay(int DayNumber){
switch (DayNumber)
{
case 0:
return "Sunday";
case 1:
return "Monday";
case 2:
return "Tuesday";
case 3:
return "Wednesday";
case 4:
return "Thursday";
case 5:
return "Friday";
case 6:
return "Saturday";
}
}
结尾加个最终返回 return ""之类就行。例如 return "Saturday"; } return ""; }

[soli11722984]

加個DEFAULT