How to update Jtable based on itemStateChanged in JComboBox?

Question

My bad... I originally posted this topic in the Java Programming forum before I found this forum. My apologies.
Anyway, can someone help me out pls? I need to be able to update my JTable based on the selected item in the combobox. Unfortunately, my JTable doesn't update when I choose another item in the combo box. What am I doing wrong? I've read about TableModels but I'm not quite sure how to use it.
my code:
my_constructor()
JComboBox cbdisease;
cbdisease = new JComboBox();
cbdisease.setEditable(false);
cbdisease.setBounds(30,20,270,25);
add(cbdisease);
cbdisease.addActionListener(this);
cbdisease.addItem("View All");
//aside from "View All" that was previously added to the combo box
//get the values from the database to fill the comboBox
showDiseases();
cbdisease.addItemListener(new ItemListener()
public void itemStateChanged(ItemEvent e)
System.out.println(cbdisease.getSelectedItem());
displayRules();
}// end constructor
method: showDiseases
connect to DB and get D_Description (column in database)
display D_Description in combo box
public void showDiseases()
Connection conn = null;
ResultSet rs = null;
Statement statement = null;
try {
// Connect to DB
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection("jdbc:mysql:///dbused",
"root", "");
// create a statement, execute query
statement = conn.createStatement();
rs = statement.executeQuery("SELECT DISTINCT D_Description FROM disease");
//place D_Description in combo box
while(rs.next())
strDesc = rs.getString("D_Description");
cbdisease.addItem(strDesc);
conn.close();
statement.close();
} catch (SQLException sqle) {
sqle.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}//end catch
}//end showDiseases()
method: displayRules
connect to DB and get the rules depending item selected in the combo box
display the rules in a table
public void displayRules()
Connection conn = null;
ResultSet rs = null;
Statement statement = null;
try {
// Connect to DB
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection("jdbc:mysql:///dbused",
"root", "");
// create a statement, execute query
statement = conn.createStatement();
if(cbdisease.getSelectedItem().equals("View All"))
rs = statement.executeQuery("SELECT D_DiseaseCode, D_Description, D_QuestionCode, D_Question, D_Action, D_NumArrow, D_Arrow FROM Disease ORDER BY D_DiseaseCode, D_QuestionCode");
else //query depends on the item selected in combo box other than "View All"
rs = statement.executeQuery("SELECT D_DiseaseCode, D_Description, D_QuestionCode, D_Question, D_Action, D_NumArrow, D_Arrow FROM Disease WHERE" + " D_Description = '" +cbdisease.getSelectedItem()+ "' ORDER BY D_DiseaseCode, D_QuestionCode");
// Convert the result set into an array of Objects
Object[][] rows = getObjects(rs);
// These are the column headings displayed in the JTable
String[] headings = { "Disease Code", "Description", "Question Code", "Question", "Action", "# of Arrows", "Arrow"};
// Initialize a JTable with the rows of objects and column headings
rulestable = new JTable(rows, headings);
// Add the table to a JScrollPane to make it display nicely
rulesScroll = new JScrollPane(rulestable);
// Add the scroll pane to the container
add(rulesScroll);
rulesScroll.setBounds(30,80,720,380);
conn.close();
statement.close();
} catch (SQLException sqle) {
//sqle.printStackTrace();
System.out.println(sqle.getSQLState());
} catch(Exception e) {
System.err.println("Exception: " + e.getMessage());
}//end displayRules()
method: getObjects
public Object[][] getObjects(ResultSet rs) throws SQLException
// Find out how many columns are in the result set
ResultSetMetaData metaData = rs.getMetaData();
final int colCount = metaData.getColumnCount();
ArrayList rows = new ArrayList();
Object[] row = null;
while (rs.next()) {
// for each row in the result set, put every column into a temporary Object array
row = new Object[colCount];
for (int a = 0; a < colCount; a++)
row[a] = rs.getObject(a+1);
// add the temporary Object array to the array list
rows.add(row);
// convert the array list to objects
return (Object[][])rows.toArray(new Object[0][0]);
}//end getObjects()

Answer 1

Just pass the new data to a new TableModel object's
constructor and then u can use this new table model in
ur JTable constructor. that woud automatically update
the table data.
Cheers!
Asimsir Asim, do you mean inserting
DefaultTableModel rulesmodel = new DefaultTableModel(rows, headings);
to my code?
public void displayRules()
Connection conn = null;
ResultSet rs = null;
Statement statement = null;
try {
// Connect to DB
Class.forName("com.mysql.jdbc.Driver").newInstance();
conn = DriverManager.getConnection("jdbc:mysql:///dbused",
"root", "");
// create a statement, execute query
statement = conn.createStatement();
if(cbdisease.getSelectedItem().equals("View All"))
rs = statement.executeQuery("SELECT D_DiseaseCode, D_Description, D_QuestionCode, D_Question, D_Action, D_NumArrow, D_Arrow FROM Disease ORDER BY D_DiseaseCode, D_QuestionCode");
else //query depends on the item selected in combo box other than "View All"
rs = statement.executeQuery("SELECT D_DiseaseCode, D_Description, D_QuestionCode, D_Question, D_Action, D_NumArrow, D_Arrow FROM Disease WHERE" + " D_Description = '" +cbdisease.getSelectedItem()+ "' ORDER BY D_DiseaseCode, D_QuestionCode");
// Convert the result set into an array of Objects
Object[][] rows = getObjects(rs);
// These are the column headings displayed in the JTable
String[] headings = { "Disease Code", "Description", "Question Code", "Question", "Action", "# of Arrows", "Arrow"};
// Initialize a JTable with the rows of objects and column headings
rulestable = new JTable(rows, headings);
// Add the table to a JScrollPane to make it display nicely
rulesScroll = new JScrollPane(rulestable);
// Add the scroll pane to the container
add(rulesScroll);
rulesScroll.setBounds(30,80,720,380);
conn.close();
statement.close();
DefaultTableModel rulesmodel = new DefaultTableModel(rows, headings); //like this?
rulestable.setModel(rulesmodel);     
} catch (SQLException sqle) {
//sqle.printStackTrace();
System.out.println(sqle.getSQLState());
} catch(Exception e) {
System.err.println("Exception: " + e.getMessage());
}//end displayRules()