JTable AutoCreateRowSorter sorting Numbers As Strings

Question

I have a JTable:

JTable table = new JTable();
String[] colNames = {"c1"};
DefaultTableModel model = new DefaultTableModel();

Integer[] x = new Integer[10];
int[] xi = {0,1,2,3,4,5,6,7,8,9};
for (int i=0; i<10; i++){
    x[i]=new Integer(xi[i]);
}model.addColumn("c1");

table.setModel(model);
table.setEnabled(false);
table.setAutoCreateRowSorter(true);
JScrollPane scrollpane = new JScrollPane(table);
contentPane.add(scrollpane);

Now when I load this and click on a column title the rows sort as if they were Strings:

0,10... (in order of length)

How can i change this so they order numerically?

Answer 1

This is because the RowSorter calls TableModel.getColumnClass(int index) to get the Class associated to the column in index position and use its Comparator to do the sort.

DefaultTableModel extends from AbstractTableModel and doesn't override getColumnClass(int columnIndex) method:

public Class<?> getColumnClass(int columnIndex) {
    return Object.class;
}

As you can see it always return Object.class. To properly sort your column, you need to override getColumnClass method.

Answer 2

How can i change this so they order numerically?

Override the getColumnClass() method of your TableModel to return Integer.class and the Integer Comparator will be used to sort the data instead of the String comparator.