public class MathDemo {
    public static void main(String[] args) throws ParseException {
        System.out.println("pi:"+Math.PI);
        System.out.println("E:"+Math.E);


        System.out.println("abs"+Math.abs(-10));
        System.out.println("ceil"+Math.ceil(12.35));


        System.out.println("floor"+Math.floor(12.56));

        System.out.println("max"+Math.max(12,36));

        System.out.println("Max:"+Math.max(Math.max(12,86),Math.max(25,98)));
        System.out.println("pow"+Math.pow(3,4));
    long ge =3;
        System.out.println(Math.pow(ge,100));

        System.out.println(System.currentTimeMillis());
long start=System.currentTimeMillis();
for (int i=0;i<10000000;i++)
{
    System.out.println("hello"+i);

}
        long endt=System.currentTimeMillis();

        double diff=endt-start;
        System.out.println(diff/1000);


        long tinestamp=System.currentTimeMillis();
        Date date1=new Date(tinestamp);
        System.out.println();

        long time =0;
        Date date=new Date(9999999);
        System.out.println(date.toLocaleString());

        SimpleDateFormat simpleDateFormat=new SimpleDateFormat("yyyy年MM月dd日 hh:mm:ss");
        Date date  =new Date();
        String strDate=simpleDateFormat.format(date);
        System.out.println(strDate);

        String strDate2="2015/08/09";
        SimpleDateFormat simpleDateFormat1=new SimpleDateFormat("yyyy/MM/dd");
        Date date2=simpleDateFormat1.parse(strDate2);
        System.out.println(date2.toLocaleString());

你已经来到世界上多少天

package array;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;

public class LiveDate {
    public static void main(String[] args) throws ParseException {
        System.out.println("请输入出生日期：");
        Scanner scanner =new Scanner(System.in);
        String strBirthDate=scanner.next();
        SimpleDateFormat simpleDateFormat=new SimpleDateFormat("yyyy/mm/dd");
        Date date=simpleDateFormat.parse(strBirthDate);

        long  birth_time =date.getTime();

        Date date1=new Date();


        long now_time=date1.getTime();

        long diff = now_time - birth_time;

        long  days = diff/1000/60/60/24;

        System.out.println( "你已经来到世界上"+ days+"天");