Auto resizing the JTable column widths

Question

I need my JTable to automatically re-size its column widths to fit the content. I found the TableColumnAdjuster class very useful. But there's a small problem. Say i have 5 columns, and their content is very short. In that case, if i use the auto adjuster, it sets the first four columns widths according to their content and gives all the rest of space to the last column. Please see the example.

Here the last column, Balance is given all the excess space. But what if i need to give that space to one of the middle columns. In the above case, i need to assign that space to the third column, name. I tried modifying the TableColumnAdjuster class's adjustColumns() method. But I couldn't get it working.

I tried both column.setPreferredWidth() and column.setWidth() for changing column sizes. But seems it doesn't change anything. How can I effectively change the column sizes of a JTable. If there's some other alternative or a direct answer to my main problem, that's better. Thanks!

Answer 1

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);

Answer 2

There is no option to automatically resize one column larger than the other.

Maybe you can to something like:

tca = new TableColumnAdjuster( table, 0 );
tca.adjustColumns();
TableColumnModel tcm = table.getColumnModel();  
TableColumn tc = tcm.getColumn(1);
tc.setWidth(tc.getWidth() + 25);

This would allow you to add extra space to column 1. This extra space would only be added the first time the table is displayed.

Another option is to use:

table.setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS);

This would allocate extra space proportionally to each column.

Answer 3

setAutoResizeMode() will tell your table how to resize you should give it a try will all different options available to see the differences, in My case I wanted to specifically resize two columns and let it decide how to adjust all the other ones.

jTable1.setAutoResizeMode(JTable.AUTO_RESIZE_NEXT_COLUMN);
TableColumnModel colModel=jTable1.getColumnModel();
colModel.getColumn(1).setPreferredWidth(25);    
colModel.getColumn(2).setPreferredWidth(400);

Answer 4

You can do this:

JPanel jp = new JPanel();
jp.add(table);

jp.setLayout(new GridLayout(1,1)); /* little trick ;) and believe me that this step is important to the automatic all columns resize! A import is also needed for using GridLayout*/
table.setAutoResizeMode(JTable.AUTO_RESIZE_ALL_COLUMNS); // this is obvius part