Java Data Type - 如何format将日期值字符串另一个字符串格式

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

public class Main
{
    public static void main(String[] args) throws Exception
    {
        String source= new String("03/20/2015");
        SimpleDateFormat sdfinput = new SimpleDateFormat("MM/dd/yyyy");
        SimpleDateFormat sdfoutput = new SimpleDateFormat("yyyy-MM-dd");
        Date inputdate=sdfinput.parse(source);
            String outputDate=sdfoutput.format(inputdate);
        System.out.println(outputDate);
    }
}