docs: java connect example free resource

docs/examples/java/src/main/java/com/taos/example/ConnectCloudExample.java

@@ -10,12 +10,12 @@ import java.sql.Statement;
 public class ConnectCloudExample {
     public static void main(String[] args) throws SQLException {
         String jdbcUrl = System.getenv("TDENGINE_JDBC_URL");
-        Connection conn = DriverManager.getConnection(jdbcUrl);
-        Statement stmt = conn.createStatement();
+        try(Connection conn = DriverManager.getConnection(jdbcUrl)) {
+            try(Statement stmt = conn.createStatement()) {
                 // test the connection by firing a query
                 stmt.executeQuery("select server_version()");
-        stmt.close();
-        conn.close();
+            }
+        }
     }
 }
 // ANCHOR_END: connect