时间转换

public String getTime(String time,String str){
  String timeString = "";
  String nian = time.substring(0, 4);
         String yue = time.substring(5,7);
         String ri = time.substring(8, 10);
         String shi = time.substring(11,13);
         String fen = time.substring(14, 16);
  if(str=="年月日"){
   timeString = nian+"年"+yue+"月"+ri+"日";
  }else if(str=="年月"){
   timeString = nian+"年"+yue+"月";
  }else if(str=="年月日时"){
   timeString = nian+"年"+yue+"月"+ri+"日"+shi+"时";
  }else if(str=="年月日时分"){
   timeString = nian+"年"+yue+"月"+ri+"日"+shi+"时"+fen+"分";
  }else if(str=="年月日时分秒"){
      String miao = time.substring(17, 19);
   timeString = nian+"年"+yue+"月"+ri+"日"+shi+"时"+fen+"分"+miao+"秒";
  }else{
   timeString = nian+"-"+yue+"-"+ri;
  } 
  return timeString;
 }