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


public class Test {

    public static void main(String[] args) throws ParseException {
        //当前时间
        Date now = new Date(); 
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        //Date转换成String 
        System.out.println(df.format(now));

        //String转换成Date
        Date daTime=df.parse(df.format(now));
        long longTime;
        //年月日转换成时间戳
        longTime = daTime.getTime();
        System.out.println(longTime);
        
        //时间戳增加24小时转换成年月日
        long lt = longTime+24*3600*1000;
        Date date = new Date(lt);
        String res = df.format(date);
        System.out.println(res);
    }
}