add an empty row to the Jtable

[hany hashemi]

Hi everybody,
I have a Jtable and i am going to add an empty row after pressing a button named insert.
Whenever i put these following code in my class ,it works properly.

  
    model = new DefaultTableModel(data,columnNames);
    model.insertRow(table.getRowCount(),new Object[]{"","","","",""}); 

I should add after these 2 lines i create a JScrollPane and add it to the getContentPane().

THE PROBLEM:
Whenever i put these 2 lines in a seperate function like addRow() and call this function after pressing the insert button , i see no changes in Jtable,i mean a new empty row isn't added to the table.
I think i should add a new table to the JScrollPane but since i'm a new programmer in java ,i don't know how to do this.

Can anyone help me please?

[Olivier Legat]

hany hashemi wrote:
Whenever i put these following code in my class ,it works properly.

...

Where exactly in the class are you putting these instruction?

hany hashemi wrote:
Whenever i put these 2 lines in a seperate function like addRow() and call this function after pressing the insert button , i see no changes in Jtable

Why wouldn't it? If it works elsewhere in the class I don't see why it wouldn't work inside a method like addRow().

Post more of your code. An example when it works, and an example when it doesn't.

[hany hashemi]

 
 private void btInsActionPerformed(ActionEvent evt) {
        insertRows(data,columnNames);
 }
 private void insertRows(Vector data,Vector col){
        // Insert the last row
        model = new DefaultTableModel(data,col);
        model.insertRow(table.getRowCount(),new Object[]{"","","","",""});
        table = new JTable(data, col);
        scrollPane = new JScrollPane( table );
        getContentPane().add( scrollPane );
  }

This part of code took a long time and i will be appreciative if you can help me solving my problem.
Thanks in advance.

[Rob Spoor]

That's because you're creating a new JTable that does not share the TableModel. You then wrap that JTable in a JScrollPane and add that to the center of the content pane, removing the previous component.

[hany hashemi]

Sorry i didn't get it.
You mean i should delete the following lines from the code:

        table = new JTable(data, col);   
        scrollPane = new JScrollPane( table );   
        getContentPane().add( scrollPane );   

so i just have these lines in the insertRow() function:

   
        model = new DefaultTableModel(data,col);
        model.insertRow(table.getRowCount(),new Object[]{"","","","",""});

but it still doesn't work properly yet...

Would you please tell me what should i do now?

[denis sorn]

He meant, you need to get an existing TableModel from the JTable. For example I have used DefaultTableModel (suggesting you to consider it to) and when I want to add a new row (when there are no more empty rows in the table) to the table I get its existing Model and add the new row to it:

        //fromDate and toDate in form yyyy-mm-dd hh:mm:ss
    //i.e. "2008-11-26 06:00:00", "2009-02-15 05:00:00"
 public void addNewPeriodT1(String name, String fromDate, String toDate)
 {
        insertingRowT1 = true;
        int numOfRows = jTable1.getModel().getRowCount();
        dbm.addPeriod(name, fromDate, toDate, connection);
        DefaultTableModel table1Model = (DefaultTableModel)jTable1.getModel();
        Object[] emptyRow = new Object[6];
        if(++numberOfPeriods >= numOfRows)
            table1Model.addRow(emptyRow);
        
        periodNamesMap.put(name, numberOfPeriods -1);   //get(String periodName) returns a row number for that period
        periodNamesMap2.put(numberOfPeriods -1, name); //get(int row) returns period name associated with the row
        jTable1.setValueAt(name, numberOfPeriods -1, 0);
        insertingRowT1 = false;
 }  

[Mikko Kohtamäki]

# private void insertRows(Vector data,Vector col){  
#         // Insert the last row  
#         model = new DefaultTableModel(data,col);  
#         model.insertRow(table.getRowCount(),new Object[]{"","","","",""});  
#         table = new JTable(data, col);  
#         scrollPane = new JScrollPane( table );  
#         getContentPane().add( scrollPane );  
#   }


   public void init(Vector data,Vector col) {
        model = new DefaultTableModel(data,col);
        table = new JTable(model);
        scrollPane = new JScrollPane( table );
        getContentPane().add( scrollPane );
    }

    private void insertEmptyRow(){  
         // Insert the last row  
        model.insertRow(model.getRowCount(),new Object[]{"","","","",""});  
    } 

[Brian Cole]

hany hashemi wrote:
You mean i should delete the following lines from the code:

        table = new JTable(data, col);   
        scrollPane = new JScrollPane( table );   
        getContentPane().add( scrollPane );   

so i just have these lines in the insertRow() function:

   
        model = new DefaultTableModel(data,col);
        model.insertRow(table.getRowCount(),new Object[]{"","","","",""});

but it still doesn't work properly yet...

Almost. You need to delete the model = new DefaultTableModel(data,col) line also. (You want to add a row to the existing table model, not instantiate a separate table model.)

Of course you need to ensure your model variable gets initialized (one time only) to the actual table model you are using before calling insertRow().

[hany hashemi]

Thanks for your help.
I did what you suggested and removed a code which was declaring a new model while adding a new row.But it still doesn't work.I get so frustrated and completely confused. :!:
This is a new part of my code:

    
 private void btInsActionPerformed(ActionEvent evt) {
         model = new DefaultTableModel(data,columnNames); 
        insertRows(data,columnNames);
 }
 private void insertRows(Vector data,Vector col){
        model.insertRow(table.getRowCount(),new Object[]{"","","","",""});
  }

[Brian Cole]

hany hashemi wrote:Thanks for your help.
I did what you suggested and removed a code which was declaring a new model while adding a new row.But it still doesn't work.I get so frustrated and completely confused. :!:
This is a new part of my code:

    
 private void btInsActionPerformed(ActionEvent evt) {
         model = new DefaultTableModel(data,columnNames); // <---------- you really need to get rid of this line!
        insertRows(data,columnNames);
 }
 private void insertRows(Vector data,Vector col){
        model.insertRow(table.getRowCount(),new Object[]{"","","","",""});
  }

You are still calling model = new DefaultTableModel(data,columnNames) each time the user clicks the button, right? Stop doing that.

[hany hashemi]

I put it outside of the method.I mean before pressing the insert button ,i declare a model and inside the insertRow i just add row.BUT ... ???!!!
evrything is just like before,without any changes...

[Michael Dunn]

you seem to have missed the point of everyone - get rid of the 'new' table model.

probably easier to give you a working example and have you try to follow it

    
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.table.*;

class Testing
{
  JTable table;
  int x = 0;
  public void buildGUI()
  {
    DefaultTableModel dtm = new DefaultTableModel(0,3);
    table = new JTable(dtm);
    for(int x = 0; x < 10; x++) insertRow();
    JScrollPane sp = new JScrollPane(table);
    JButton btn = new JButton("Insert Row");
    JFrame f = new JFrame();
    f.getContentPane().add(sp);
    f.getContentPane().add(btn,BorderLayout.SOUTH);
    f.pack();
    f.setLocationRelativeTo(null);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setVisible(true);
    btn.addActionListener(new ActionListener(){
      public void actionPerformed(ActionEvent ae){
        insertRow();
      }
    });
  }
  public void insertRow()
  {
    ((DefaultTableModel)table.getModel()).addRow(new java.util.Vector<String>(java.util.Arrays.asList(new String[]{String.valueOf(x++),"",""})));
  }
  public static void main(String[] args)
  {
    SwingUtilities.invokeLater(new Runnable(){
      public void run(){
        new Testing().buildGUI();
      }
    });
  }
}

[Dinesh Jayram]

Thanks Michael Dunn I used your code for my project