Question

I want to add elements in JList from an user-defined function which is not any event listener.

I have JList as :

DefaultListModel listModel = new DefaultListModel();
JList jList1 = new JList(listModel);
listModel.add(0,"Welcome");
listModel.addListDataListener(new MyListDataListener());

class MyListDataListener implements ListDataListener {
        public void contentsChanged(ListDataEvent e) {
             //DefaultListModel model = (DefaultListModel)e.getSource();
            //jList1.setModel(listModel);
            System.out.println("inside content");
        }
        public void intervalAdded(ListDataEvent e) {
           // jList1.setModel(listModel);
            jList1.setListData(a);
            //System.out.println("inside added"+e.getSource()+" "+jList1.getModel());

        }
        public void intervalRemoved(ListDataEvent e) {

        }
    }

As, intervalAdded is called whenever I want to add elements from a mouseclicked listener,as

private void sendButtonMouseClicked(java.awt.event.MouseEvent evt) {                                        
        // TODO add your handling code here:
        if(!inputField.getText().isEmpty())
        {
            message=myName+" : "+inputField.getText();


        listModel.add(GlobalVariable.i,message);


        inputField.setText(null);
        GlobalVariable.i++;
        }

    }

and also from my user-defined function,that is

public void messagereceived(String s)
    {
                 listModel.add(GlobalVariable.i,message);
                 GlobalVariable.i++;
}

But the listModel.setmodel() does not work whenever it called from the messagereceived() function.

How do I add element in JList from this function?

Answer 1

1. In messagereceived, you are not calling listModel.setmodel() but listModel.add(GlobalVariable.i,message);
2. When you call jList1.setListData(a); you are implicitly creating and setting a new ListModel on jList1. Therefore, when you modify listModel, it does not reflect on your jList1.
3. GlobalVariable–>looks like the sign of some ancient C code-style. Use objects appropriately instead.