泥沼の中のパフォーマンスチューニング #JJUG15. SimpleDateFormat をベタ書きで public String format(Date d) { Calendar cal = Calendar.getInstance(); cal.setTime(d); StringBuilder build = new StringBuilder(); build.append(cal.get(Calendar.YEAR)).append("/"); int month = cal.get(Calendar.MONTH) + 1; if(month < 10) {build.append('0');} build.append(month).append("/"); int dayOfMonth = ......//省略 }
