yoorijoriinfo

  It's because we didn't finally release the resources It corresponds to a violation of the web vulnerability. ex) Connection conn = null; PreparedStatement pstmt = null; ResultSet rs = null; try { // conn , pstmt , rs code }catch(NullPointerException e){ finally{ if(rs!=null){rs.close();} if(pstmt!=null){pstmt.close();} if(conn!=null){conn.close();} } 😀 Thank you !! 감사합니다 !!

Errors or error information should not be exposed to the console or on the screen. Use simple phrases only if necessary. Error information or system information should not be printed on the console or browser, but should be logged or printed in simple phrases if necessary Example of system data information disclosure (removal target code) Syste m.out.println(e.getMessage());, System.out.println(e);, e.printStackTrace();, out.println(e.getMessage()); Wrong ex) }catch(NullPointerException e){ System.out.println("Error : "+e); } } Right ex) }catch(NullPointerException e){ logger.error("ERROR-01 NullPointerException"); OR System.out.println("ERROR-01 NullPointerException"); } } 😀 Thank you !! 고마워 !!

Throwable,Exception,RuntimeException must be that  It should not be widely held, but specific exceptions such as FileNotFoundException, SQLException, IOException, ClassNotFoundEXception, etc. should be handled  !! Wring ex) } catch(Exception e) { logger.error("ERROR-01 Exception"); } Right ex) } catch( SQLException e) { logger.error("ERROR-01 SQLException"); } 😀 Thank you!! 고마워!!

class Star{ public static void main(String[] args){ for(int a=1; a<10; a=a+2){ // 1 3 5 7 9 for(int b=10; b>a; b=b-2){ // 10 8 6 4 2  System.out.print(" "); } for(int c=0; c<a; c=c+1){ // 0 1 2 3 4 5 6 7 8  System.out.print("*"); }     System.out.println(); } } } an) 😀 Thank you!! 고마워!!

int e = 1000; String str = String.valueOf(e);   System.out.println(str);  result : 1000 😀 Thank you!! 고마워!!

<%@ page import="java.text.SimpleDateFormat"%> <%@ page import="java.util.Date"%> Date todayShow1 = new Date(); String chkDateShow1 = ""; SimpleDateFormat formatShow1;  formatShow1 = new SimpleDateFormat("yyyyMMdd"); chkDateShow1 = formatShow1.format(todayShow1); String date1="20230504"; String date2=chkDateShow1; String date3="20230915"; DateFormat format = new SimpleDateFormat("yyyyMMdd"); Date d1 = format.parse( date1 ); Date d2 = format.parse( date2 ); Date d3 = format.parse( date3 ); long Sec = (d1.getTime() - d2.getTime()) / 1000; //  long Min = (d1.getTime() - d2.getTime()) / 60000; //  long Hour = (d1.getTime() - d2.getTime()) / 3600000; //  long Days = Sec / (24*60*60); //  long Sec3 = (d3.getTime() - d2.getTime()) / 1000; //  long Min3 = (d3.getTime() - d2.getTime()) / 60000; //  long Hour3 = (d3.getTime() - d2.getTime()) / 3600000; //  long Days3 = Sec3 / (24*60*60); //  <script> $(docume...

When checking for Java string inclusion ex) String str = "contains test"; System.out.println( str.contains("contains") );  // true System.out.println( str.contains("what") );  // false System.out.println( str.contains("TEST") );  // false System.out.println( str.contains("test") );  // true 😀 Thank you!! 감사합니다!!