Update ADBQuickStart.java

Addressed review comments

Author: nsundara

java/jdbc/ConnectionSamples/ADBQuickStart.java

@@ -46,34 +46,32 @@ online transaction processing operations. The Star Schema Benchmark (SSB) sample
 import oracle.ucp.jdbc.PoolDataSourceFactory;
 import oracle.ucp.jdbc.PoolDataSource;
 
-public class ADBQuickStart {
+/*
+ * The sample demonstrates connecting to Autonomous Database using 
+ * Oracle JDBC driver and UCP as a client side connection pool.
+ */
+public class ADBQuickStart { 
 
- // Make sure to have Oracle JDBC release 18c or higher 
- // to pass TNS_ADMIN as part of a connection URL.
- // TNS_ADMIN - Should be the path where the client credentials zip file is downloaded. 
- // wallet_dbname - This is the TNS Alias that you can get from tnsnames.ora.
- final static String DB_URL="jdbc:oracle:thin:@wallet_dbname?TNS_ADMIN=/Users/test/wallet_dbname/";
- // Update the Database Username to point to your Autonomous Database. For a quick testing, you can 
- // use "admin" user. 
- final static String DB_USER = "admin";
- // For security reasons, you will need to provide database password through console. 
- static String DB_PASSWORD ;
- final static String CONN_FACTORY_CLASS_NAME="oracle.jdbc.pool.OracleDataSource";
-
- /*
- * The sample demonstrates UCP as client side connection pool.
- */
  public static void main(String args[]) throws Exception {
+ // Make sure to have Oracle JDBC driver 18c or above 
+ // to pass TNS_ADMIN as part of a connection URL.
+ // TNS_ADMIN - Should be the path where the client credentials zip file is downloaded. 
+ final String DB_URL="jdbc:oracle:thin:@dbname_medium?TNS_ADMIN=/Users/test/wallet_dbname/";
+ // Update the Database Username and Password to point to your Autonomous Database
+ final String DB_USER = "admin";
+ String DB_PASSWORD = null ;
+ final String CONN_FACTORY_CLASS_NAME="oracle.jdbc.pool.OracleDataSource";
+ 
  // For security purposes, you must enter the password through the console 
  try {
  Scanner scanner = new Scanner(System.in);
  System.out.print("Enter the password for Autonomous Database: ");
  DB_PASSWORD = scanner.nextLine();
  }
- catch (Exception e) {
+ catch (Exception e) { 
  System.out.println("ADBQuickStart - Exception occurred : " + e.getMessage());
- }
- 
+  System.exit(1);
+ } 
  // Get the PoolDataSource for UCP
  PoolDataSource pds = PoolDataSourceFactory.getPoolDataSource();
 
@@ -96,36 +94,43 @@ public static void main(String args[]) throws Exception {
  // connections allowed on the connection pool.
  pds.setMaxPoolSize(20);
 
+
  // Get the database connection from UCP.
  try (Connection conn = pds.getConnection()) {
  System.out.println("Available connections after checkout: "
  + pds.getAvailableConnectionsCount());
  System.out.println("Borrowed connections after checkout: "
  + pds.getBorrowedConnectionsCount());
+ 
  // Perform a database operation
- doSQLWork(conn);
+ try {
+ doSQLWork(conn);
+ } catch (SQLException e) {
+ System.out.println("ADBQuickStart - "
+ + "doSQLWork()- SQLException occurred : " + e.getMessage());
+ } 
  }
 
  System.out.println("Available connections after checkin: "
  + pds.getAvailableConnectionsCount());
  System.out.println("Borrowed connections after checkin: "
  + pds.getBorrowedConnectionsCount());
- } 
-
- /*
- * Selects 20 rows from the SH (Sales History) Schema that is the accessible to all 
- * the database users of autonomous database. 
- */
- public static void doSQLWork(Connection conn) {
- 
- try {
- conn.setAutoCommit(false);
- // Prepare a statement to execute the SQL Queries.
- try (Statement statement = conn.createStatement() ) {
+ }
+ /*
+ * Selects 20 rows from the SH (Sales History) Schema that is the accessible to all 
+ * the database users of autonomous database. 
+ */
+ private static void doSQLWork(Connection conn) throws SQLException {
+ String queryStatement = "SELECT CUST_ID, CUST_FIRST_NAME, CUST_LAST_NAME, CUST_CITY," 
+ + "CUST_CREDIT_LIMIT FROM SH.CUSTOMERS WHERE ROWNUM < 20 order by CUST_ID";
+ 
+ System.out.println("Query is " + queryStatement);
+ 
+ conn.setAutoCommit(false);
+ // Prepare a statement to execute the SQL Queries.
+ try (Statement statement = conn.createStatement(); 
  // Select 20 rows from the CUSTOMERS table from SH schema. 
- try (ResultSet resultSet = statement.executeQuery ("select CUST_ID," 
- + "CUST_FIRST_NAME, CUST_LAST_NAME, CUST_CITY, CUST_CREDIT_LIMIT "
- + "FROM SH.CUSTOMERS WHERE ROWNUM < 20 order by CUST_ID ") ) {
+ ResultSet resultSet = statement.executeQuery(queryStatement)) {
  System.out.println("\nCUST_ID" + " " + "CUST_FIRST_NAME" + " " + "CUST_LAST_NAME" 
  + " " + "CUST_CITY" + " " + "CUST_CREDIT_LIMIT");
  System.out.println("-----------------------------------------------------------");
@@ -134,16 +139,8 @@ public static void doSQLWork(Connection conn) {
  resultSet.getString(3)+ " " + resultSet.getString(4) + " " +
  resultSet.getInt(5));
  }
- System.out.println("\nSuccessfully established a connection to Autonomous Database\n");
- }
- }
- }
- catch (SQLException e) {
- System.out.println("ADBQuickStart - "
- + "doSQLWork()- SQLException occurred : " + e.getMessage());
- } 
- } // doSQLWork
- 
-} // ADBQuickStart 
-
- 
+ System.out.println("\nSuccessfully established a connection to Autonomous Database\n");
+ } 
+ } // End of doSQLWork
+ 
+} // End of ADBQuickStart