java获取当前时间的前7天时间

public String getStatetime() throws ParseException{  
  
     SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");                
  
    Calendar c = Calendar.getInstance();           
  
    c.add(Calendar.DATE, - 7);           
  
    Date time = c.getTime();         
  
    String preDay = sdf.format(time);         
  
    return preDay;   
  
 }