day4
总结：
1、闰年的判断逻辑本身很简单 %4==0&&%100!=0。
2、boolean类型只有两个值：true、false。

package day4;

public class text1 {

public static void main(String args[])
{
	int year =2022;
	System.out.print("" + year + " is ");
	
	if(!isleapyear(year))
	{
	   System.out.println("NOT .");
	}
	else
	{
		System.out.println("a leap year.");
	}
	
	year=2000;
	System.out.print("" + year + " is ");
	if(!isleapyear(year))
	{
	   System.out.print("NOT .");
	}
	else
	{
		System.out.println("a leap year.");
	}
	
	year=2004;
	System.out.print("" + year + " is ");
	if(!isleapyear(year))
	{
	   System.out.print("NOT .");
	}
	else
	{
		System.out.println("a leap year.");
	}
	
	year=2021;
	System.out.print("" + year + " is ");
	if(!isleapyear(year))
	{
	   System.out.println("NOT .");
	}
	else
	{
		System.out.println("a leap year.");
	}
	
	year=2008;
	System.out.print("" + year + " is ");
	if(!isleapyear(year))
	{
	   System.out.println("NOT .");
	}
	else
	{
		System.out.println("a leap year.");
	}
	
}

public static boolean isleapyear(int year) {
	if ((year % 4 == 0) && (year % 100 != 0) || (year % 400 == 0)) {
		return true;
	} else {
		return false;
	} // Of if
}

}

结果：