Java – sort double values in JTable

I found many problems related to this, but I didn't find a simple way to solve my problem

I can't find a way to make my JTable sort the correct double value

I extend abstracttablemodel to receive a class array and return the correct type of each column:

class TableModelMod extends AbstractTableModel{

    private ArrayList data;
    private String [] headers;
    private Class [] types;

    TableModelMod(String [] heads,ArrayList datas,Class [] classes){
        headers = heads;
        data = datas;
        types = classes;
    }
    ... 
    @Override public Class getColumnClass(int c){
        if (c > types.length - 1)
            return null;
        else 
            return types[c];
    }
...

Then in my custom JTable constructor:

TableRowSorter<TableModelMod> sorter = new TableRowSorter<TableModelMod>((TableModelMod)getModel());

However, I encountered this error when adding rows:

java.lang.IllegalArgumentException: Cannot format given Object as a Number

It is in the method decimalformat Format (object number, StringBuffer, toappendto, fieldposition POS) fails. It accepts most number types, but double

If I use another class for the double column, I have no errors, but the sorting still doesn't work as expected I've tried different number classes, but I don't seem to sort doubles correctly:

@Override public Class getColumnClass(int c){
    if (c > types.length - 1)
        return null;
    else if (types[c] == Double.class)
        return Number.class;
    else 
        return types[c];
}

I'm not sure whether I need to implement custom rowsorter, custom cellrenderer or both

Can someone guide me how to solve this simpler method?

Thank you very much and best regards

Editing: resolved

It's very embarrassing to tell where the problem is

The ArrayList containing the object [] row is populated from the database resultset using getString (int) instead of GetObject (int) or getdouble (int), so the renderer cannot use this value as a double Strangely, it does not use integer or number as the column class to provide exceptions, but it is still sorted as string I look for problems in the wrong class because I'm sure my ArrayList contains only objects

Thank you very much for your example. Looking at them, I noticed that my doubles are actually strings, and then I can find where the conversion takes place

Solution

Look at this code It sorts double values

import java.awt.BorderLayout;

import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.RowSorter;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
import javax.swing.table.TableRowSorter;

public class RowSorterDemo {
  public static void main(String args[]) {
    JFrame frame = new JFrame("Sort Table Demo");
    frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
    Object rows[][] = { { "J",23.1 },{ "R",21.1,},{ "E",21.2,{ "B",27.1,{ "A",25.2,{ "S",22.9,};

    String columns[] = { "Name","Age" };

    TableModel model = new DefaultTableModel(rows,columns) {
      public Class getColumnClass(int column) {
        Class returnValue;
        if ((column >= 0) && (column < getColumnCount())) {
          returnValue = getValueAt(0,column).getClass();
        } else {
          returnValue = Object.class;
        }
        return returnValue;
      }
    };

    JTable table = new JTable(model);

    RowSorter<TableModel> sorter = new TableRowSorter<TableModel>(model);

    table.setRowSorter(sorter);

    JScrollPane pane = new JScrollPane(table);

    frame.add(pane,BorderLayout.CENTER);

    frame.setSize(300,150);
    frame.setVisible(true);
  }
}

I slightly modified the source given by this link, so it needs to double the value