Updating JTable from a different JFrame

Question

Actually, I have a JFrame(the main window) with a JTable in it. And couple of buttons, like Add,Delete,Refresh.

Refresh uses the function(updateTable) that has the following code below and works fine:

 try
        {
            ResultSet R = Home.getStatement().executeQuery("Select * from Schooldata");
            int count =0;
            while(R.next()) {  count++; }



school_data = new String[count][6];
            R = Home.getStatement().executeQuery("Select Schoolname,city,ProgramOpted,coordinator_name,Trainers,contactnum from Schooldata");
            count =0;
            while(R.next())
            {   
                for(int i=0;i<6;i++)
                {   school_data[count][i]= R.getString(i+1);
                    System.out.println(R.getString(i+1));
                }
                count++;
            } 
        }
        catch(SQLException S)   {JOptionPane.showMessageDialog(null,S);}

         jTable1.setModel(new DefaultTableModel(school_data,new String [] {
                "School Name", "City", "Program", "Coordinator", "Trainers", "Contact Number"
            }));

When I click on "Add, another JFrame window appears and asks for Details that is further saved to Database and shows a confirmation message and refreshes the table(on a different JFrame i.e the main Window) using above function.

The Issue is, I'm calling the same function but from an another JFrame.Expecting the changes to be reflected in the main JFrame.

Using the method,new Main().updateTable(); in the below code.It's just not working.

try
            {
                int confirm = Home.getStatement().executeUpdate(Query);
                if(confirm == 1)
                {
                    JOptionPane.showMessageDialog(null,"Record Added","Saved",1);
                    new Main().updateTable();
                }
                else  JOptionPane.showMessageDialog(null,"There is some Error.....","Error",0);


            }
            catch(SQLException S)
            {
                JOptionPane.showMessageDialog(null,S,"Error",0);
            }

See [The Use of Multiple JFrames, Good/Bad Practice?](http://stackoverflow.com/q/9554636/418556) — Andrew Thompson, Sep 21 '14 at 23:24
But, actually I was doing it like, using setVisible(true) for another JFrame, and using dispose(); for the previous JFrame, Is it still not correct? — Chetan Lakhanpal, Sep 22 '14 at 15:29

score 3 · Accepted Answer · edited May 23 '17 at 12:30

Your problem I believe is here (it's hard to tell without a minimal example program:

int confirm = Home.getStatement().executeUpdate(Query);
if(confirm == 1)
{
    JOptionPane.showMessageDialog(null,"Record Added","Saved",1);
    new Main().updateTable();  // ****** HERE ******
}

You're creating a completely new Main object, changing its state, and hoping that this will change the state of the visualized Main object, but you're finding out that no, it won't.

Instead you need to pass a reference of the visualized Main object into the code above, and then call methods on it, not on a newly created completely unique object.

Whatever you do, don't try solving this by making fields or methods static. Yes, that might work, but it breaks OOPs and makes your program difficult to test or extend.

As an aside, that second dependent window should not be another JFrame, and in fact likely should be a modal JDialog. For if you use a JDialog, then there would be no need for the dialog code to push information into the calling window. Rather the calling code will know when you're done dealing with the dialog, and so at this point if the dialog's state is good (if you didn't say cancel it with no changes), then the calling code can easily pull information from the dialog code. For a concrete example of what I"m talking about, please look at my answer to a similar question about passing information between two windows here.

Also a similar problem and solution can be found here.

The OP is also creating a new instance of a JTable...have no idea whether the old ones been removed or the new one is been added +1 — MadProgrammer, Sep 21 '14 at 20:32
@MadProgrammer: thank you. Yes, an [mcve](http://stackoverflow.com/help/mcve) would be nice to clarify things! — Hovercraft Full Of Eels, Sep 21 '14 at 20:39

score 0 · Answer 2 · answered Nov 12 '14 at 17:10

See weather you are disposing the main or not. If not then try creating object of Main frame and try accessing it to refresh table. You can also add import for Main Frame .java file in your refresh dialog file and try refreshing the table. Also check if your table is public static or not so that to access it from another frame. If you create a refresh function for this purpose then it will be best. My code for function goes as -

    import package.mainframe;

or

    MainFrame mainframe = new MainFrame();
    try
        {
            int confirm = Home.getStatement().executeUpdate(Query);
            if(confirm == 1)
            {
                JOptionPane.showMessageDialog(null,"Record Added","Saved",1);
                mainframe.updateTable();    //or mainframe.functioncall();
            }
            else  JOptionPane.showMessageDialog(null,"There is some Error.....","Error",0);


        }
        catch(SQLException S)
        {
            JOptionPane.showMessageDialog(null,S,"Error",0);
        }

with static it works.. And the other case can be with JDialog. — Chetan Lakhanpal, Nov 16 '14 at 18:06

Updating JTable from a different JFrame

2 Answers2