TableColumnResizer.java

package ika.gui;

import java.awt.*;
import javax.swing.*;
import javax.swing.table.*;


/**
 * Resize the columns of a JTable for optimal display.
 * From Swing Hacks, #21.
 */
public class TableColumnResizer {
    
    public static void adjustColumnPreferredWidths(JTable table,
            boolean considerColumnHeaders) {
        // strategy - get max width for cells in column and
        // make that the preferred width
        TableColumnModel columnModel = table.getColumnModel();
        for (int col=0; col<table.getColumnCount(); col++) {
            // System.out.println ("--- col " + col + " ---");
            int maxwidth = 0;
            for (int row=0; row<table.getRowCount(); row++) {
                TableCellRenderer rend = table.getCellRenderer(row, col);
                Object value = table.getValueAt(row, col);
                Component comp =
                        rend.getTableCellRendererComponent(table,
                        value,
                        false,
                        false,
                        row,
                        col);
                maxwidth = Math.max(comp.getPreferredSize().width,
                        maxwidth);
                //System.out.println ("col " + col +
                //                    " pref width now " +
                //                    maxwidth);
            } // for row
            
            if (!considerColumnHeaders) {
                // this version of the width set doesn't consider the
                // column header's preferred width
                TableColumn column = columnModel.getColumn(col);
                column.setPreferredWidth(maxwidth);
            } else {
                // this version of the width set considers the
                // column header's preferred width too
                TableColumn column = columnModel.getColumn(col);
                TableCellRenderer headerRenderer = column.getHeaderRenderer();
                if (headerRenderer == null)
                    headerRenderer = table.getTableHeader().getDefaultRenderer();
                Object headerValue = column.getHeaderValue();
                Component headerComp =
                        headerRenderer.getTableCellRendererComponent(table,
                        headerValue,
                        false,
                        false,
                        0,
                        col);
                maxwidth = Math.max(maxwidth,
                        headerComp.getPreferredSize().width);
                column.setPreferredWidth(maxwidth);
            }
            
        } // for col
    }
}