Auto resizing the JTable column widths

You can try the next:

public void resizeColumnWidth(JTable table) {
    final TableColumnModel columnModel = table.getColumnModel();
    for (int column = 0; column < table.getColumnCount(); column++) {
        int width = 15; // Min width
        for (int row = 0; row < table.getRowCount(); row++) {
            TableCellRenderer renderer = table.getCellRenderer(row, column);
            Component comp = table.prepareRenderer(renderer, row, column);
            width = Math.max(comp.getPreferredSize().width +1 , width);
        }
        if(width > 300)
            width=300;
        columnModel.getColumn(column).setPreferredWidth(width);
    }
}

This needs to be executed before the resize method.
If you have:

table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);