自学Jav测试代码三 Math类 & Date & GregorianCalendar类

 2017-08-23 20:30:08 

writer: pprp

package test;

import java.util.Date;
import java.util.*;

public class class_test {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println(Math.pow(2, 3));
        
        double a = 100 * Math.random();
        double x = 4.51;
        
        System.out.println(a);
        System.out.println(Math.sqrt(a));
        System.out.println(Math.max(a, 10));
        
        //Math中的方法和字段属性都是静态的所以可以直接使用它们
        //四舍五入
        System.out.println(Math.round(x));
        //向下取整
        System.out.println(Math.floor(x));
        
        //测试时间和日期的类date
        //输出当前时间
        System.out.println(new Date());
        
        //测试日历的类GregorianCalendar
        GregorianCalendar gc = new GregorianCalendar();
        int y = gc.get(Calendar.MONTH);
        System.out.println(y);
        
        gc.set(Calendar.YEAR, 2019);
        System.out.println(gc.get(Calendar.YEAR));
        gc.set(2017,8,17);
        System.out.println(gc.get(Calendar.YEAR));
        System.out.println(gc.get(Calendar.MONTH));
        System.out.println(gc.get(Calendar.DATE));
        
        //获得系统当前时间
        String now = gc.get(Calendar.YEAR) + "年" + gc.get(Calendar.MONTH)
+ "月" + gc.get(Calendar.DATE) + "日" + gc.get(Calendar.HOUR) + "小时" + gc.get(Calendar.MINUTE) + "分"
+ gc.get(Calendar.SECOND) + "秒" ;
        System.out.println(now);
        
        //给你一个人的生日，分析每年的生日是星期几？
        final char[] kor_week = {'日','一','二','三','四','五','六'};
        for(int i = 2010 ; i <= 2020 ; i++)
        {
            gc.set(i,Calendar.JULY,20); //设置日期
            char week = kor_week[gc.get(Calendar.DAY_OF_WEEK) - 1];
            System.out.println(i + "年的生日是星期" + week);
        }
        
    }

}