refactor: use try-with-resources for cash id db operations

src/main/java/client/inventory/manipulator/MapleCashidGenerator.java

@@ -19,65 +19,50 @@
 */
 package client.inventory.manipulator;
 
+import tools.DatabaseConnection;
+
 import java.sql.Connection;
 import java.sql.PreparedStatement;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.util.HashSet;
 import java.util.Set;
-import tools.DatabaseConnection;
 
 /**
- *
  * @author RonanLana
  */
 public class MapleCashidGenerator {
-    
+
     private final static Set<Integer> existentCashids = new HashSet<>(10000);
     private static Integer runningCashid = 0;
-    
+
     private static void loadExistentCashIdsFromQuery(Connection con, String query) throws SQLException {
-        PreparedStatement ps = con.prepareStatement(query);
-        ResultSet rs = ps.executeQuery();
-        
-        while (rs.next()) {
-            int id = rs.getInt(1);
-            if (!rs.wasNull()) {
-                existentCashids.add(id);
+        try (PreparedStatement ps = con.prepareStatement(query);
+             ResultSet rs = ps.executeQuery()) {
+
+            while (rs.next()) {
+                int id = rs.getInt(1);
+                if (!rs.wasNull()) {
+                    existentCashids.add(id);
+                }
             }
         }
-        
-        rs.close();
-        ps.close();
     }
-    
+
     public static synchronized void loadExistentCashIdsFromDb() {
-        Connection con = null;
-        try {
-            con = DatabaseConnection.getConnection();
-            
+        try (Connection con = DatabaseConnection.getConnection()) {
             loadExistentCashIdsFromQuery(con, "SELECT id FROM rings");
             loadExistentCashIdsFromQuery(con, "SELECT petid FROM pets");
-            
-            con.close();
         } catch (SQLException ex) {
             ex.printStackTrace();
-        } finally {
-            try {
-                if (con != null && !con.isClosed()) {
-                    con.close();
-                }
-            } catch (SQLException e) {
-                e.printStackTrace();
-            }
         }
-        
+
         runningCashid = 0;
         do {
             runningCashid++;    // hopefully the id will never surpass the allotted amount for pets/rings?
         } while (existentCashids.contains(runningCashid));
     }
-    
+
     private static void getNextAvailableCashId() {
         runningCashid++;
         if (runningCashid >= 777000000) {
@@ -85,23 +70,23 @@ public class MapleCashidGenerator {
             loadExistentCashIdsFromDb();
         }
     }
-    
+
     public static synchronized int generateCashId() {
         while (true) {
             if (!existentCashids.contains(runningCashid)) {
                 int ret = runningCashid;
                 getNextAvailableCashId();
-                
+
                 // existentCashids.add(ret)... no need to do this since the wrap over already refetches already used cashids from the DB
                 return ret;
             }
-            
+
             getNextAvailableCashId();
         }
     }
-    
+
     public static synchronized void freeCashId(int cashId) {
         existentCashids.remove(cashId);
     }
-    
+
 }