Question

By default, when you try to copy from a JTable, the toString method of the value(s) being copied are sent to the clipboard. How can I change this behavior for one class of objects?

Let’s say I have a table with two columns for simplicity’s sake. The first column has Booleans in it and the second column has Strings. Currently when you copy a Boolean, you get either true or false. How could I change this behavior to place an arbitrary string on the clipboard (say t for true and f for false) without changing the copy behavior of String?

Here’s a SSCCE where you can copy / paste from a JTable.

import java.awt.BorderLayout;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.WindowConstants;
import javax.swing.table.AbstractTableModel;

public class ChangeCopyBehavior {
    private static class TestModel extends AbstractTableModel {
        private static final long serialVersionUID = -774558262249729206L;

        @Override
        public int getRowCount() {
            return 4;
        }

        @Override
        public int getColumnCount() {
            return 2;
        }

        @Override
        public Class<?> getColumnClass(int col) {
            return col == 0 ? Boolean.class : String.class;
        }

        @Override
        public Object getValueAt(int rowIndex, int columnIndex) {
            if (columnIndex == 1) {
                return "String";
            } else {
                return rowIndex % 2 == 0;
            }
        }
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JTable table = new JTable(new TestModel());
                table.setCellSelectionEnabled(true);

                JPanel panel = new JPanel();
                panel.setLayout(new BorderLayout());
                panel.add(new JScrollPane(table), BorderLayout.CENTER);
                panel.add(new JTextArea("Paste stuff here"), BorderLayout.SOUTH);

                JFrame frame = new JFrame("Test");
                frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
                frame.setContentPane(panel);
                frame.pack();
                frame.setVisible(true);
            }
        });
    }
}

Answer 1

Create a custom TransferHandler to export the data in whatever format you want.

Here is a link to the old ExtendedDnDDemo from the Swing tutorial that show an example of a custom TableTransferHandler.