Trees.java

package tk.amberide.ide.swing.tree;

// @author santhosh kumar T - santhosh@in.fiorano.com

import javax.swing.*;
import javax.swing.tree.TreePath;
import java.util.StringTokenizer;

public class Trees {

    // is path1 descendant of path2?
    public static boolean isDescendant(TreePath path1, TreePath path2) {
        int count1 = path1.getPathCount();
        int count2 = path2.getPathCount();
        if (count1 <= count2) {
            return false;
        }
        while (count1 != count2) {
            path1 = path1.getParentPath();
            count1--;
        }
        return path1.equals(path2);
    }

    public static String getExpansionState(JTree tree, int row) {
        TreePath rowPath = tree.getPathForRow(row);
        StringBuilder buf = new StringBuilder();
        int rowCount = tree.getRowCount();
        for (int i = row; i < rowCount; i++) {
            TreePath path = tree.getPathForRow(i);
            if (i == row || isDescendant(path, rowPath)) {
                if (tree.isExpanded(path)) {
                    buf.append(",").append(String.valueOf(i - row));
                }
            } else {
                break;
            }
        }
        return buf.toString();
    }

    public static void restoreExpanstionState(JTree tree, int row, String expansionState) {
        StringTokenizer stok = new StringTokenizer(expansionState, ",");
        while (stok.hasMoreTokens()) {
            int token = row + Integer.parseInt(stok.nextToken());
            tree.expandRow(token);
        }
    }
}