Converting an ArrayList into a 2D Array

Question

In Java how do you convert a ArrayList into a two dimensional array Object[][]?

From comments: I will describe you the problem with more details: an XML file inclu

Answer 1

I presume you are using the JTable(Object[][], Object[]) constructor.

Instead of converting an ArrayList into an Object[][], try using the JTable(TableModel) constructor. You can write a custom class that implements the TableModel interface. Sun has already provided the AbstractTableModel class for you to extend to make your life a little easier.

public class ContactTableModel extends AbstractTableModel {

    private List contacts;

    public ContactTableModel(List contacts) {
        this.contacts = contacts;
    }

    public int getColumnCount() {
        // return however many columns you want
    }

    public int getRowCount() {
        return contacts.size();
    }

    public String getColumnName(int columnIndex) {
        switch (columnIndex) {
        case 0: return "Name";
        case 1: return "Age";
        case 2: return "Telephone";
        // ...
        }
    }

    public Object getValueAt(int rowIndex, int columnIndex) {
        Contact contact = contacts.get(rowIndex);

        switch (columnIndex) {
        case 0: return contact.getName();
        case 1: return contact.getAge();
        case 2: return contact.getTelephone();
        // ...
        }
    }

}

Later on...

List contacts = ...;
TableModel tableModel = new ContactTableModel(contacts);
JTable table = new JTable(tableModel);