Problems with JTable sorting of integer values

Question

Currently I have a JTable that uses RowSorter, but when I click the header that I want it to sort in, it displays the rows in a weird order

Answer 1

You can set the column type for a JTable by setting its model explicitly like in the following example

setModel(new DefaultTableModel(new Object[0][], new String[] {
                "SELECT", "WHERE", "FIELD", "TYPE" }) {
            Class[] types = { Boolean.class, Boolean.class, String.class,
                    String.class };
            boolean[] canEdit = { true, false, false, false };

            @Override
            public Class getColumnClass(int columnIndex) {
                return this.types[columnIndex];
            }

            public boolean isCellEditable(int columnIndex) {
                return this.canEdit[columnIndex];
            }
        });

Give your column classes like this (here column one and two are Boolean and the rest String.

 Class[] types = { Boolean.class, Boolean.class, String.class,String.class };

Answer 2

You're treating the row contents as text. Your sort order is alphabetical rather than numerical. If you treat the contents as numbers it should work itself out.

Answer 3

To meet your requirement, you just sets the Comparator for RowSorter to use when sorting the specified column. The code somewhat like below:

table.setAutoCreateRowSorter(true);
TableRowSorter<DefaultTableModel> rowSorter = (TableRowSorter<DefaultTableModel>)table.getRowSorter();
rowSorter.setComparator(5, new Comparator<String>() {

        @Override
        public int compare(String o1, String o2)
        {
            return Integer.parseInt(o1) - Integer.parseInt(o2);
        }

    });

Answer 4

You must add the below code to your actual code that doesn't sort your column as Integer.

Your actual code to build your JTable is:

DefaultTableModel modeloT = new DefaultTableModel(); 
// But Sorts the column of numbers in wrong way. 1,11,2,25,......

SOLUTION:

DefaultTableModel modeloT = new DefaultTableModel() {

// Defining the type of column on your JTable. I wish sort my second column as a numeric (1,2,11), not String (1,11,2). For that I defined the second class as Integer.
Class[] types = { String.class, Integer.class, String.class };
boolean[] canEdit = new boolean [] {
    false, false, false
};

    // You must add this Override in order to works sorting by numeric.
@Override
public Class getColumnClass(int columnIndex) {
        return this.types[columnIndex];
        }       

     // This override is just for avoid editing the content of my JTable. 
@Override
public boolean isCellEditable(int row, int column) {
        return false;
        }
};

Answer 5

I was also trying to achieve what you were trying to do and I struggled to understand how to do it myself. The way I achieved the "proper" sorting was as such:

DefaultTableModel model = new DefaultTableModel(row, col){
    @Overrride
     public Class getColumnClass(int c) {
         return getValueAt(0, c).getClass();
     }
});

Answer 6

To expand on @aaamos' answer, verify that your TableModel returns Number.class (or a suitable subclass) from getColumnClass(). There's a related example here.