java - How can i rewrite this methods without duplication? -


how can make code without duplication? methods similar.

method create phone numbers:

   private list<string> createphonenumbers(string sqlstatement, long id) {         list<string> phones = new arraylist<>();         try (preparedstatement statement = this.connection.preparestatement(sqlstatement)) {             statement.setlong(1, id);             try (resultset resultset = statement.executequery()) {                 while (resultset.next()) {                     phones.add(resultset.getstring("phonenumber"));                 }                 return phones;             }         } catch (sqlexception e) {             e.printstacktrace();             return null;         }     }

method create friend list:

   private list<account> createfriendlist(string sqlstatement, long id) {         list<account> friends = new arraylist<>();         try (preparedstatement statement = this.connection.preparestatement(sqlstatement)) {             statement.setlong(1, id);             try (resultset resultset = statement.executequery()) {                 while (resultset.next()) {                     friends.add(createsimpleelement(resultset));                 }                 return friends;             }         } catch (sqlexception e) {             e.printstacktrace();             return null;         }     }

method create group list: 

   private list<group> creategrouplist(string sqlstatement, long id) {         list<group> groups = new arraylist<>();         try (preparedstatement statement = this.connection.preparestatement(sqlstatement)) {             statement.setlong(1, id);             try (resultset resultset = statement.executequery()) {                 while (resultset.next()) {                     groups.add(creategroupfromresultset(resultset));                 }                 return groups;             }         } catch (sqlexception e) {             e.printstacktrace();             return null;         }     }

this bad solution.

 //field values: 1- create string, 2 - createaccount, 3 - creategroup private <e> list<e> createlist(string selectsql, long id, int field) {     list<e> list = new arraylist<>();     try (preparedstatement statement = this.connection.preparestatement(selectsql)) {         statement.setlong(1, id);         try (resultset resultset = statement.executequery()) {             while (resultset.next()) {                 switch (field) {                     case 1:                         list.add((e) resultset.getstring("phonenumber"));                         break;                     case 2:                         list.add((e) createsimpleelement(resultset));                         break;                     case 3:                         list.add((e) creategroupfromresultset(resultset));                         break;                 }             }             return list;         }     } catch (sqlexception e) {         e.printstacktrace();         return null;     } }

what can read solve similar problems in code?

sounds me should check out spring jdbc , it's callback-based jdbctemplate approach. abstracts boilerplate (database connections, transactions, exception translation etc.) away , lets focus on application code.

sample:

list<actor> actors = this.jdbctemplate.query(         "select first_name, last_name t_actor",         new rowmapper<actor>() {             public actor maprow(resultset rs, int rownum) throws sqlexception {                 actor actor = new actor();                 actor.setfirstname(rs.getstring("first_name"));                 actor.setlastname(rs.getstring("last_name"));                 return actor;             }         });

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