[JAVA] DateFormat is not thread safe

As shown below, when I kept an instance of [DateFormat] 1 as a member variable and reused it, a crash report came up in Fabric.

class Util {

   companion object {
       private val sDateFormat = SimpleDateFormat("yyyy/MM/dd")

       fun convert(date: Date): String {
           return sDateFormat.format(date)
       }
   }

}

After investigating, it is an implementation that is called from multiple threads, and as shown in [Document] 1, it was changed to generate an instance every time.

class Util {

   companion object {
       fun convert(date: Date): String {
           return SimpleDateFormat("yyyy/MM/dd").format(date)
       }
   }

}