Updating a JTable

[Mousa A. Rafi]

I'm having trouble updating a JTable. I've a JTable that's showing certain fields. But when I want to assign a new JTable there, the change isn't seen. In the following code, when the [bold]button is clicked, no change occurs. How can I achieve the desired behaviour?[/bold]

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
class TableProb{
private JTable jt;
 
public TableProb(){
JFrame jf = new JFrame("Table Problem");
jf.setSize(300, 400);
jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 
JPanel panel = new JPanel(new BorderLayout());
 
jt = getTable1();
 
panel.add(new JScrollPane(jt), BorderLayout.CENTER);
 

JButton jb = new JButton("Change Table");
panel.add(jb, BorderLayout.PAGE_END);
 
jf.setContentPane(panel);
jf.setVisible(true);
 
jb.addActionListener(new ActionListener(){
public void actionPerformed(ActionEvent e){
jt = getTable2();
}
});
 
}
 
private JTable getTable1(){
String[][] columns = new String[][]{{"This", "is"},
{"a", "table"}, {"it", "works!"}};
String[] headings = new String[] {"Column 1", "Column 2"};
return new JTable(columns, headings);
}
 
private JTable getTable2(){
String[][] columns = new String[][]{{"This", "is"},
{"another", "table"}, {"it don't", "work  :(  "}};
String[] headings = new String[] {"Column 1", "Column 2"};
return new JTable(columns, headings);
}
 
public static void main(String[] args){
new TableProb();
}
}  

[Craig Wood]

A gui is its own little world. Once you add a component to it, it (the gui) owns and manages the component. Pointing the reference to another component has no affect on the component previously added, it just means that you can no longer use the reference to get to the added component. To change components the technique is to first remove a component from the gui. Then you are free to add another in its place.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
 
class TableProb {
    private JTable jt;
    int tableNumber;
    JScrollPane scrollPane;
 
    public TableProb() {
        jt = getTable1();
        tableNumber = 1;
        scrollPane = new JScrollPane(jt);
        JPanel panel = new JPanel(new BorderLayout());
        panel.add(scrollPane, BorderLayout.CENTER);
 
        JButton jb = new JButton("Change Table");
        jb.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                scrollPane.remove(jt);    // remove existing component first
                if(tableNumber == 1)
                {
                    jt = getTable2();
                    tableNumber = 2;
                }
                else
                {
                    jt = getTable1();
                    tableNumber = 1;
                }
                scrollPane.getViewport().setView(jt);  // then add new one
            }
        });
        panel.add(jb, BorderLayout.PAGE_END);
 
        // JFrame code all together
        JFrame jf = new JFrame("Table Problem");
        jf.setSize(300, 400);
        jf.setLocation(200,200);
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jf.setContentPane(panel);
        jf.setVisible(true);     // keep this last
    }
 
    private JTable getTable1() {
        String[][] columns = new String[][] {
            {"This", "is"}, {"a", "table"}, {"it", "works!"}
        };
        String[] headings = new String[] {"Column 1", "Column 2"};
        return new JTable(columns, headings);
    }
 
    private JTable getTable2() {
        String[][] columns = new String[][] {
            {"This", "is"}, {"another", "table"}, {"it don't", "work  "}
        };
        String[] headings = new String[] {"Column 1", "Column 2"};
        return new JTable(columns, headings);
    }
 
    public static void main(String[] args) {
        new TableProb();
    }
}

[Gregg Bolinger]

Lightning Bug,

Welcome to Javaranch! We don't have too many rules around here but we do have a Naming Policy. Please read this and adjust your display name accordingly. You can change your display name by clicking [url=https://coderanch.com/forums/user/edit]here[url].

Thanks.

[Mousa A. Rafi]

Gregg Bolinger::
Sorry about not conforming with the policy. Actually I was not so much aware of the fact. The reason for not using my real name is that I wanted to avoid any sort of discrimination. Anyway I will change the name.

Craig Wood::
Thanks for your reply to the original thread. It was of a great help to me in programming with SWING and understand them better.

[ February 07, 2005: Message edited by: Lightning Bug ]
[ February 07, 2005: Message edited by: Lightning Bug ]

[Gregg Bolinger]

Originally posted by Lightning Bug:
Gregg Bolinger::
Sorry about not conforming with the policy. Actually I was not so much aware of the fact. The reason for not using my real name is that I wanted to avoid any sort of discrimination. Anyway I will change the name.

No problem. We feel that Javaranch is a pretty friendly place and we have a host of different people from all over the world here but on the offchance you do feel discrimated against please notify me or another Bartender or Sheriff immediatly and we will take care of the situation ASAP.

Thanks and again, welcome to Javaranch!!