Best way to attack this problem

Question

I am trying to make a hot backup java program for Oracle. I am new to both jdbc and java in general.
If my entry point class is
// file connectme.java
package cm;
import java.sql.*; // Package for JDBC classes.
import java.util.*;
public class connectme
public static void main(String[] args)
connClass conn1 = new connClass(); // this class makes the connection to Oracle
hotBackUp hotBackUp1 = new hotBackUp();
hotBackUp1.getDBA_Data_Files();
// end
the class connClass looks like
// in file connClass.java
package cm;
import java.sql.*; // Package for JDBC classes.
import java.util.*;
public class connClass{
// Database Connection Object
Connection m_connection = null;
public connClass(){
System.out.println("in connectme");
this.dbConnection(); // Sets up DB connection
if (m_connection != null){
System.out.println("we connected");
else{
System.out.println("damit not connected");
public void dbConnection() {
try {
System.out.println("Trying to connect to the Database...");
DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
String l_dbConnectString =
"(DESCRIPTION=(ADDRESS=(HOST="+ConnectionParams.s_hostName+")"+
"(PROTOCOL=tcp)(PORT="+ConnectionParams.s_portNumber+"))"+
"(CONNECT_DATA=(SID="+ConnectionParams.s_databaseSID+")))";
m_connection = DriverManager.getConnection(
"jdbc:oracle:thin:@"+l_dbConnectString,
ConnectionParams.s_userName, ConnectionParams.s_password);
m_connection.setAutoCommit(false);
System.out.println("Connected to "+ConnectionParams.s_databaseSID+
" Database as "+ConnectionParams.s_userName+".");
} catch(SQLException ex){ // Trap SQL errors
System.out.println("Error in Connecting to the Database "+ex.toString());
// end
and hotBackUp looks like
// in file hotBackUP.java
package cm;
import java.sql.*; // Package for JDBC classes.
import java.util.*;
public class hotBackUp{
// default constructor
public hotBackUp(){}
* This method retrieves data from dba_data_files
public void getDBA_Data_Files(){
try{
System.out.println("Trying to get dba_data_files information");
Statement l_stmt = conn1.m_connection.createStatement();
ResultSet l_resultSet = l_stmt.executeQuery(
"select TABLESPACE_NAME,FILE_NAME from dba_data_files "+
"order by TABLESPACE_NAME");
while(l_resultSet.next()){
System.out.println(l_resultSet.getString(1) ); // Tablespace Name
System.out.println(l_resultSet.getString(2) ); // File Name
l_stmt.close(); // Close the Statement
} catch(SQLException ex) {  // Trap SQL Errors
int i = ex.getErrorCode();
System.out.println("ERROR ORA-"+i);
// end
The issue I am having is hotBackUp.getDBA_Data_Files cannot find the conn1.m_connection.createStatemet() the compile fails. How can class hotBackUp know about the other class? Should I use a Interface or Inner Class?

Answer 1

And even nicer is to extend connClass as a base class for hotBackUp.
// file connectme.java
package cm;
public class connectme {
  public static void main(String[] args) {
    hotBackUpSubClass hotBackUpSub2 = new hotBackUpSubClass();
    hotBackUpSub2.getDBA_Data_Files();
    hotBackUpSub2.closeConnection();
}// end
// in file hotBackUpSubClass.java
package cm;
import java.sql.*; // Package for JDBC classes.
*  This class now extends connClass, so we do without
*  the aggregation syntax.  Everything we handled for
*  the connection object in the hotBackUp regular class,
*  has been inherited from connClass in this new variation
*  of hotBackUp.
public class hotBackUpSubClass extends connClass {
   * default constructor
  public hotBackUpSubClass(){
    super();
   * This method retrieves data from dba_data_files
  public void getDBA_Data_Files(){
    try{
      System.out.println("Trying to get dba_data_files information");
      Statement l_stmt = getConnection().createStatement();
      ResultSet l_resultSet = l_stmt.executeQuery(
        "SELECT username, authID FROM webportal.webuser" );
//        "select TABLESPACE_NAME,FILE_NAME from dba_data_files "+
//        "order by TABLESPACE_NAME" );
      while(l_resultSet.next()){
        System.out.println( l_resultSet.getString(1) ); // Tablespace Name
        System.out.println( l_resultSet.getString(2) ); // File Name
      l_stmt.close(); // Close the Statement
    } catch(SQLException ex) { // Trap SQL Errors
      int i = ex.getErrorCode();
      System.out.println("ERROR ORA-"+i);
}// endHere is the raw text of the whole thing again.
// file connectme.java
package cm;
public class connectme {
public static void main(String[] args) {
* we didn't follow this train of thought...
*connClass conn1 = new connClass();
* This class makes its own connection to Oracle
* from within itself, by using an instance of
* your connClass object ...aggregation ??
hotBackUp hotBackUp1 = new hotBackUp();
hotBackUpSubClass hotBackUpSub2 = new hotBackUpSubClass();
* This is now a self connecting 'entity',
* which performs a single database activity.
hotBackUp1.getDBA_Data_Files();
hotBackUpSub2.getDBA_Data_Files();
// Remember to also close the database connection
hotBackUp1.closeConnection();
hotBackUpSub2.closeConnection();
}// end
// in file connClass.java
package cm;
import java.sql.*; // Package for JDBC classes.
public class connClass{
* Database Connection Object.
* This is what we are encapsulating, we need to
* provide convenience methods to let outsiders
* make use of its 'self contained' existence.
private Connection m_connection = null;
public connClass(){
System.out.println("in connectme");
this.dbConnection(); // Sets up DB connection
if (m_connection != null){
System.out.println("we connected");
else{
System.out.println("What a surprise, not connected!");
* We needed a convenience method to grab the connection.
public Connection getConnection() {
return m_connection;
* We needed a convenience method to close the connection.
* We politely call this when we are done with this object.
public void closeConnection() {
if(m_connection != null) {
try {
m_connection.close();
} catch(SQLException ex){ // Trap SQL errors
System.out.println(
"Error closing Connecting to the Database " +
ex.toString()
public void dbConnection() {
try {
System.out.println("Trying to connect to the Database...");
* DriverManager.registerDriver(new oracle.jdbc.driver.OracleDriver());
* Hmmm, the above gives me grief ...this is another option.
try {
Class.forName( "oracle.jdbc.driver.OracleDriver" );
} catch ( ClassNotFoundException e )
{ System.out.println( "Could not load OracleDriver" ); }
// I showed you my raw url here, make sure yours is correct.
String /** -- IP:PORT:SID */
l_dbConnectString = "127.0.0.1:1521:GumB",
s_password = "guest",
s_userName = "portalguest";
"(DESCRIPTION=(ADDRESS=(HOST="+ConnectionParams.s_hostName+")"+
"(PROTOCOL=tcp)(PORT="+ConnectionParams.s_portNumber+"))"+
"(CONNECT_DATA=(SID="+ConnectionParams.s_databaseSID+")))";
m_connection = DriverManager.getConnection(
"jdbc:oracle:thin:@"+l_dbConnectString,
/**ConnectionParams.*/s_userName,
/**ConnectionParams.*/s_password
m_connection.setAutoCommit(false);
// System.out.println("Connected to "+ConnectionParams. s_databaseSID+
// " Database as "+ConnectionParams.s_userName+".");
} catch(SQLException ex){ // Trap SQL errors
System.out.println("Error in Connecting to the Database "+ex.toString());
}// end
// in file hotBackUpSubClass.java
package cm;
import java.sql.*; // Package for JDBC classes.
* This class now extends connClass, so we do without
* the aggregation syntax. Everything we handled for
* the connection object in the hotBackUp regular class,
* has been inherited from connClass in this new variation
* of hotBackUp.
public class hotBackUpSubClass extends connClass {
* default constructor
public hotBackUpSubClass(){
super();
* This method retrieves data from dba_data_files
public void getDBA_Data_Files(){
try{
System.out.println("Trying to get dba_data_files information");
Statement l_stmt = getConnection().createStatement();
ResultSet l_resultSet = l_stmt.executeQuery(
"SELECT username, authID FROM webportal.webuser" );
// "select TABLESPACE_NAME,FILE_NAME from dba_data_files "+
// "order by TABLESPACE_NAME" );
while(l_resultSet.next()){
System.out.println( l_resultSet.getString(1) ); // Tablespace Name
System.out.println( l_resultSet.getString(2) ); // File Name
l_stmt.close(); // Close the Statement
} catch(SQLException ex) { // Trap SQL Errors
int i = ex.getErrorCode();
System.out.println("ERROR ORA-"+i);
}// end
// in file hotBackUp.java
package cm;
import java.sql.*; // Package for JDBC classes.
public class hotBackUp{
* Now here we can treat that connection object like
* an entity, one that knows how to do its own work.
connClass connectionObj;
* default constructor
* A good place to instantiate the connection entity.
public hotBackUp(){
connectionObj = new cm.connClass();
* This lets outsiders signal that they are through with hotBackUP,
* so that it can tell the database connection to close.
* You get a bunch of rogue connections laying around in
* your system if you leave these hanging around open.
public void closeConnection() {
connectionObj.closeConnection();
* This method retrieves data from dba_data_files
public void getDBA_Data_Files(){
try{
System.out.println("Trying to get dba_data_files information");
Statement l_stmt = connectionObj.getConnection().createStatement();
ResultSet l_resultSet = l_stmt.executeQuery(
"SELECT username, authID FROM webportal.webuser" );
// "select TABLESPACE_NAME,FILE_NAME from dba_data_files "+
// "order by TABLESPACE_NAME" );
while(l_resultSet.next()){
System.out.println( l_resultSet.getString(1) ); // Tablespace Name
System.out.println( l_resultSet.getString(2) ); // File Name
l_stmt.close(); // Close the Statement
} catch(SQLException ex) { // Trap SQL Errors
int i = ex.getErrorCode();
System.out.println("ERROR ORA-"+i);
}// end