Java小程序之——判断输入的某个年份是否是闰年

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编写程序，判断给定的某个年份是否是闰年。

闰年的判断规则如下：

（1）若某个年份能被4整除但不能被100整除，则是闰年。

（2）若某个年份能被400整除，则也是闰年。

程序一：

package exercise;

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class IsLeapYear {
public static  boolean isNum(String str){
boolean isNum=true;
for(int i=0;i<str.length();i++){
//mark if the year is a number;
            isNum=false;
if(str.codePointAt(i)>47&&str.codePointAt(i)<58){
                isNum=true;
            }
if(isNum==false){
break;
            }

        }//for
        
return isNum;
    }

public void isHeapYear(){
int year=0;

        System.out.println("Please input the year you want to judge:");

        Scanner in=new Scanner(System.in);
        String temp=in.next();

if(!isNum(temp)){
             System.out.println("the year you input is not valid");
        }else{
            year=Integer.parseInt(temp);
if(year<1980||year>2050){
                System.out.println("the year you input is not in the scale");
                System.exit(1);
            }else  if((year%4==0&&year%100!=0)||year%400==0){
                System.out.println(year+" is a leap year");
            }else{
                System.out.println(year+" is not a leap year");
            }
        }

    }
public static void main(String[] args){

new IsLeapYear().isHeapYear();

    }
}

　　程序二：

package exercise;

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class IsLeapYearReg {

public static  boolean isNum(String str){
        Pattern p = Pattern.compile("[0-9]*");  
        Matcher isNum = p.matcher(str);  
if(isNum.matches()){
return true;
        }else{
return false;
        }
    }

public void isHeapYear(){
int year=0;

        System.out.println("Please input the year you want to judge:");

        Scanner in=new Scanner(System.in);
        String temp=in.next();

if(!isNum(temp)){
             System.out.println("the year you input is not valid");
        }else{
            year=Integer.parseInt(temp);
if(year<1980||year>2050){
                System.out.println("the year you input is not in the scale");
                System.exit(1);
            }else  if((year%4==0&&year%100!=0)||year%400==0){
                System.out.println(year+" is a leap year");
            }else{
                System.out.println(year+" is not a leap year");
            }
        }
    }

public static void main(String[] args){
new IsLeapYearReg().isHeapYear();
    }
}