Simple Example, I Need Help!

Question

I'm working on a very simple application using Eclipse and MySQL here it is:
http://img.photobucket.com/albums/v335/shlumph/table.jpg
It's pretty self-explanitory. You enter a person's first and last name, press submit, and their name flops onto the table. I made this naively, and do not know how to make use of reflection and beans, if that's even what I need.
I tried googling on how to make use of reflection and beans when dealing with database connectivity, but there's just so much different kinds of information, it's like trying to find a needle in a haystack.
If someone could help point me in a direction to go, post some in depth tutorials, or even point out a good book that I can get on amazon, that would be excellent!
Just incase if you care what I have done naively, here is the database structure and code:
I have a database named addressbook with a table called names. Inside of names there are the following columns:
first_name varchar(20)
last_name varchar(20)
public class example extends Composite {
     private Label firstNameLbl = null;
     private Text firstNameTxt = null;
     private Label lastNameLbl = null;
     private Text lastNameTxt = null;
     private Composite tableComposite = null;
     private Button submitButton = null;
     private Table nameTable = null;
     private Connection con = null;
     public example(Composite parent, int style) {
          super(parent, style);
          initialize();
     }//example()
     private void initialize() {
          GridData gridData1 = new GridData();
          gridData1.widthHint = 75;
          GridLayout gridLayout = new GridLayout();
          gridLayout.numColumns = 2;
          firstNameLbl = new Label(this, SWT.NONE);
          firstNameLbl.setText("First Name");
          firstNameTxt = new Text(this, SWT.BORDER);
          lastNameLbl = new Label(this, SWT.NONE);
          lastNameLbl.setText("Last Name");
          lastNameTxt = new Text(this, SWT.BORDER);
          this.setLayout(gridLayout);
          Label filler1 = new Label(this, SWT.NONE);
          submitButton = new Button(this, SWT.NONE);
          submitButton.setText("Submit");
          submitButton.setLayoutData(gridData1);
          submitButton
                    .addSelectionListener(new org.eclipse.swt.events.SelectionAdapter() {
                         public void widgetSelected(org.eclipse.swt.events.SelectionEvent e) {
                              getConnection();
                              try {
                                   String firstName = firstNameTxt.getText();
                                   String lastName = lastNameTxt.getText();
                                   String sql = "INSERT names VALUES ('" + firstName + "', '" + lastName + "')";
                                   Statement stmt = con.createStatement();
                                   stmt.executeUpdate(sql);
                                   //Update the table
                                   nameTable.removeAll();
                                   addItems();
                                   //Close connections
                                   con.close();
                                   stmt.close();
                              } catch (SQLException e2) {
                                   e2.printStackTrace();
                         }//widgetSelected()
          createTableComposite();
          this.setSize(new Point(241, 220));
     }//initialize()
      * This method initializes tableComposite     
     private void createTableComposite() {
          GridData gridData2 = new GridData();
          gridData2.widthHint = 200;
          gridData2.heightHint = 100;
          GridData gridData = new GridData();
          gridData.horizontalSpan = 2;
          tableComposite = new Composite(this, SWT.NONE);
          tableComposite.setLayout(new GridLayout());
          tableComposite.setLayoutData(gridData);
          nameTable = new Table(tableComposite, SWT.BORDER);
          nameTable.setHeaderVisible(true);
          nameTable.setLayoutData(gridData2);
          nameTable.setLinesVisible(true);
          TableColumn firstNameCol = new TableColumn(nameTable, SWT.LEFT);
          firstNameCol.setText("First Name");
          firstNameCol.setWidth(100);
          TableColumn lastNameCol = new TableColumn(nameTable, SWT.LEFT);
          lastNameCol.setText("Last Name");
          lastNameCol.setWidth(100);
          getConnection();
          addItems();
     }//createTableComposite()
      * This gets the MySQL Connection
     public void getConnection() {
          try {
           Class.forName("com.mysql.jdbc.Driver").newInstance();
           con = DriverManager.getConnection("jdbc:mysql:///addressbook", "root", "password");
         } catch(Exception e) {
           System.err.println("Exception: " + e.getMessage());
     }//getConnection()
      * This adds items to the address table
     private void addItems() {
          try {
               String sql = "SELECT first_name, last_name FROM names";
               Statement stmt = con.createStatement();
               ResultSet rs = stmt.executeQuery(sql);
               while(rs.next()) {
                    String first_name = rs.getString(1);
                    String last_name = rs.getString(2);
                    String[] row = new String[]{first_name, last_name};
                    TableItem item1 = new TableItem(nameTable, 0);
                    item1.setText(row);
          } catch (SQLException e) {
               e.printStackTrace();
     }//addItems()
} Message was edited by:
shlumph

Answer 1

Yes, the id column is auto-increment and not null. I
kind of went on a rampage without reading your latter
post and added some more stuff.So tell me why I bothered?
I added in other columns: street, city, state, phone
and email to my database. As well as
fields/setters/getters to my Person class.What does adding more columns do when you can't even insert what you had? Seems foolish. Do the easy thing first, then expand.
I think I went on a different, but similar route then
what you mentioned with the database utility. Mine's the right way. 8)
I
tried making a MySQL generator
interface/implementation along with a PersonDao
interface/implementation, like you mentioned.
Can you give me some more suggestions, I'm sure this
is done noobly/poorly.I like that find idiom for method names. Why did you copy the interface I gave you and add "search"? The idea would be to add find methods that have different parameters. In your case, I'd have a find that takes two String arguments.
It's not just being picky. Consistency matters. If you published this, a user would be likely to think "Why two find methods and a search? Did two people write this?" Pick one and stick to it.
It's great, except for that search method. After all, it's what I gave you.
>
To give you an example, here is my implementation for
methods delete, and find:
     public void delete(Person p) {
          mysql.delete("names", "id", p.getID().toString());
     public Person find(Long id) {
          Person p = new Person();
ResultSet rs = mysql.find("names", "id",
", id.toString());
          try {
               while (rs.next()) {
                    String firstName = rs.getString(1);
                    String lastName = rs.getString(2);
                    String street = rs.getString(4);
                    String city = rs.getString(5);
                    String state = rs.getString(6);
                    String zipCode = rs.getString(7);
                    String phone = rs.getString(8);
                    String email = rs.getString(9);
                    p.setID(id);
                    p.setFirstName(firstName);
                    p.setLastName(lastName);
                    p.setStreet(street);
                    p.setCity(city);
                    p.setState(state);
                    p.setZipCode(zipCode);
                    p.setPhone(phone);
                    p.setEmail(email);;
          } catch (SQLException e) {
               e.printStackTrace();
          mysql.closeConnection();
          return p;
     }// find()Here is my MySqlGenerator interface:
public interface MySqlGenerator {
     public ResultSet selectAll(String table);
public ResultSet find(String table, String pkColumn,
, String pkValue);
public ResultSet search(String table, String column,
, String search);
public List<Object> select(String table, String
g column);
public void update(String table, String column,
, String pkColumn, String pkValue, String newValue);
public void save(String table, String column, String
g values);
public void delete(String table, String pkColumn,
, String pkValue);
     public void closeConnection();
}And to give you an example, here is the
implementation for delete and find:
public void delete(String table, String pkColumn,
, String pkValue) {
          getConnection();
          try {
               Statement stmt = con.createStatement();
String sql = "DELETE FROM " +table+ " WHERE "
E " +pkColumn+ "=" + pkValue;
               stmt.executeUpdate(sql);
          } catch (SQLException e) {
               e.printStackTrace();
          } finally {
               closeConnection();
public ResultSet find(String table, String pkColumn,
, String pkValue) {
          getConnection();
          ResultSet rs = null;
          try {
               Statement stmt = con.createStatement();
String sql = "SELECT * FROM" +table+ " WHERE "
E " +pkColumn+ "=" + pkValue;
               rs = stmt.executeQuery(sql);
          } catch (SQLException e) {
               e.printStackTrace();
          return rs;
     }So theoretically, if this was done well (which I'm
sure it's not), I could put PersonDao, PersonDaoImpl,
MySqlGenerator, MySqlGeneratorImpl, all into a
package named persistence?I don't see what that MySqlGenerator is all about.
No, I wouldn't recommend doing it this way. Put it all the in the PersonDaoImpl. Better yet, create a subpackage "jdbc" under persistence and put the PersonDaoImpl in there. JDBC is one way to implement this interface. There are lots of others. But this is what you should do to start.
NEVER return a ResultSet from a method that way. Load the contents into an object or data structure and close it inside the method that created it. You're leaking a database cursor that way, AND you're exposing SQL stuff to clients. Keep all the persistence artifacts inside the persistence package. Don't let them leak out that way.
Nope, sorry, I don't think this is it.
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