Database Access delays-how to improve upon that?

Question

Hi friends,
I have this simple class,which takes in query and returns the results.I don't know why the database access is so slow,and if i try to add my driver load statements into the constructor the java class starts throwing "null pointer exception"(Java Class code given below)..I don't know much about connection pool,can u just have a look at this simple class,and tell me if there's anything on which i can improve upon and where to add the(*.close() statements).The same query runs instantly if i make a php program.Urgent help needed...please help me guys.
public class getResultSet{  private Connection con = null;  private Statement st = null;  private String dsn = "jdbc    b2j:net:xxx";  private String uname = "xxx";  private String pwd = "xxx";  private String query = "";  ResultSet results;   public void ResultS()throws Exception{      try{          Class.forName("com.ibm.db2.jcc.DB2Driver");          con = DriverManager.getConnection(dsn, uname, pwd);          st = con.createStatement(ResultSet.TYPE_SCROLL_INSENSITIVE,                                   ResultSet.CONCUR_READ_ONLY);         }      catch (SQLException e) {          e.printStackTrace();          }     }     public ResultSet getResults(String query){            results = null;            try{               results = st.executeQuery(query);               }               catch(SQLException sqle){                 sqle.printStackTrace();               }            return results;     }   }

Answer 1

Some comments on the code
public class getResultSet{ // Class names should start with a capital letter and be nouns
private Connection con = null;
private Statement st = null; // Statements are transient and should probably not be a member variable
private String dsn = "jdbc    b2j:net:xxx";  // dsn, user, pass should be final
private String uname = "xxx"; 
private String pwd = "xxx"; 
private String query = "";  // Seems you're not using this
ResultSet results;   // This really shouldn't be declared here
public void ResultS()throws Exception{ // Method should start with a lower-case letter and be a verb/* The client code is supposed to call this, then the other method?
Very fragile. I'm guessing NullPointerExceptions occur if ResultS
is not called first. Have the other method call this one as necessary.
try{        
Class.forName("com.ibm.db2.jcc.DB2Driver");
con = DriverManager.getConnection(dsn, uname,
uname, pwd);
st =
st =
=
con.createStatementResultSet.TYPE_SCROLL_INSENSITIVE,
ResultSet.CONCUR_READ_ONLY);
ultSet.CONCUR_READ_ONLY);
catch (SQLException e) {  
e.printStackTrace();
public ResultSet getResults(String query){      
results = null;
try{          
results = st.executeQuery(query);
catch(SQLException sqle){   
sqle.printStackTrace();
return results; // It's a bad idea to return ResultSets as that leaves resources open
} // Where's the cleanup? You're leaving ResultSet, Statement, Connection open
>It is probably slow because opening connections takes a long time. You may or may not need a connection pool depending on your app. Perhaps you can just open a connection at the beginning and leave it open until your app finishes. That should reduce the overhead and still be very simple.