package yanhongyun; public class NextDay { private int year; private int month; private int day; public NextDay() { } public NextDay(int year,int month,int day) { set(year,month,day); } public void set(int year,int month,int day) { if (year<0) this.year=0; else this.year=year; if (month<1 || month>12) this.month=1; else this.month=month; if (day<1 || day>lastDay(year,month)) this.day=1; else this.day=day; } private int lastDay(int year,int month) { if (month==1 || month==3 || month==5 ||month==7 || month==8 || month==10||month==12) { return 31; } else if (month==2) { if ((year%4==0 && year%100!=0) || year %400==0) 

return 29; else return 28; } else { return 30; } } public NextDay nextDay() { day=day+1; if (day>lastDay(year,month)) { day=1; month=month+1; if (month>12) { month=1; year=year+1; } } return this; } public boolean equals(Object obj) { if (obj instanceof NextDay) { NextDay nd=(NextDay)obj; return (nd.year==this.year && nd.month==this.month && nd.day==this.day); } else return false; } public String tndString() { String str=year+"年"+month+"月"+day+"日"; return str; } } 

Junit 测试程序 package yanhongyun; import junit.framework.Assert; import junit.framework.TestCase; public class TestNextDay extends TestCase { NextDay date1; NextDay date2; public TestNextDay(String name) { super(name); } public void setUp() { } public void testSet() { date1=new NextDay(2000,2,30); date2=new NextDay(2000,2,1); Assert.assertEquals(date2,date1); date1.set(1969,8,29); assertEquals(date1,date1); date1.set(1991,2,29); assertEquals(new NextDay(1991,2,1),date1); date1.set(-120,2,1); assertEquals(new NextDay(0,2,1),date1); date1.set(-120,-2,-1); assertEquals(new NextDay(0,1,1),date1); } public void testNextDay() { date1=new NextDay(1992,12,31); date2=new NextDay(1993,1,1); 

assertEquals(date2,date1.nextDay()); date1.set(1992,2,28); date2.set(1992,2,29); assertEquals(date2,date1.nextDay()); date1.set(1992,2,29); date2.set(1992,3,1); assertEquals(date2,date1.nextDay()); date1.set(1998,2,28); date2.set(1998,3,1); assertEquals(date2,date1.nextDay()); date1.set(1995,1,19); date2.set(1995,1,20); assertEquals(date2,date1.nextDay()); date1.set(2006,1,31); date2.set(2006,2,1); assertEquals(date2,date1.nextDay()); date1.set(2006,4,30); date2.set(2006,5,1); assertEquals(date2,date1.nextDay()); } public static void main(String []args) { junit.textui.TestRunner.run(TestNextDay.class); } }