SimpleDateFormat:

算出生至现在一共多长时间：

package westos;

import javax.xml.bind.SchemaOutputResolver;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Scanner;

public class Birth {
    public static void main(String[] args) throws ParseException {
        System.out.println("请输入您的出生日期，格式xxxx-xx-xx");
        Scanner scanner = new Scanner(System.in);
        String next = scanner.next();
        SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
        Date date = simpleDateFormat.parse(next);
        long time = date.getTime();
        long time2 = new Date().getTime();
        long time3 = (time2 - time) / 1000 / 60 / 60 / 24;
        System.out.println("距您出生到现在一共浪费" + time3 + "tian了");
    }
}