getActualMinimun()的使用 以及 闰年的判定方法

1.Calendar里的getActualMinimun(int field)和getActualMaximun(int field)方法

如下图所示，我们就可以直接得到相应的最小日期或者最大日期

package test2;

import java.text.SimpleDateFormat;
import java.util.Calendar;

public class dateTest {
	
	SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	private static final boolean MIN_DATE = true;	//最小date
	private static final boolean MAX_DATE = false;	//最大date
	
	public static void main(String[] args) {
		dateTest dt = new dateTest();
		System.out.println(dt.getDate(2018, 07, MIN_DATE));
		System.out.println(dt.getDate(2020, 02, MAX_DATE));
		System.out.println(dt.getDate(2019, 02, MAX_DATE));
	}
	
	//获取时间方法
	public String getDate(int year, int month, boolean status){
		Calendar calendar = Calendar.getInstance();
		calendar.set(Calendar.YEAR, year);
		calendar.set(Calendar.MONTH, month-1);
		if(status){
			calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMinimum(Calendar.DAY_OF_MONTH));
			calendar.set(Calendar.HOUR_OF_DAY, calendar.getActualMinimum(Calendar.HOUR_OF_DAY));
			calendar.set(Calendar.MINUTE, calendar.getActualMinimum(Calendar.MINUTE));
			calendar.set(Calendar.SECOND, calendar.getActualMinimum(Calendar.SECOND));
		} else {
			calendar.set(Calendar.DAY_OF_MONTH, calendar.getActualMaximum(Calendar.DAY_OF_MONTH));
			calendar.set(Calendar.HOUR_OF_DAY, calendar.getActualMaximum(Calendar.HOUR_OF_DAY));
			calendar.set(Calendar.MINUTE, calendar.getActualMaximum(Calendar.MINUTE));
			calendar.set(Calendar.SECOND, calendar.getActualMaximum(Calendar.SECOND));
		}
		String date = sdf.format(calendar.getTime());
		return date;
	}

}

输出结果如下：

2.判断某一年是否为闰年

boolean year = new GregorianCalendar().isLeapYear(2008);     //true（闰年）

boolean year = new GregorianCalendar().isLeapYear(1900);     //false（平年）