Java时间戳转换为date

data型换成时间戳
gtSendTime2 = gtSendTime.getTime();
 //Date或者String转化为时间戳
       SimpleDateFormat format =   new SimpleDateFormat( "yyyy-MM-dd HH:mm:ss" );
       String time="1970-01-06 11:45:55";
       Date date = format.parse(time);
       System.out.print("Format To times:"+date.getTime());
//时间戳转化为Sting或Date      
SimpleDateFormat format =  newSimpleDateFormat("yyyy-MM-dd HH:mm:ss");  
 Long time=newLong(445555555);  
 String d = format.format(time); 
Date date=format.parse(d);