There is the following class that implements the Runnable interface:
public class TreeHandler implements Runnable { private String name; private JTree tree; private Tree model; public TreeHandler(String name, JTree tree) { this.name = name; this.tree = tree; model = (Tree)tree.getModel(); } @Override public void run() { Node node; String nodeName; int nodeNum; System.out.println(name + " started"); while (true) { System.out.println(name + " want to find node for handling"); synchronized (tree) { while (true) { Node root = (Node)(model.getRoot()); if (root == null || !isNumber(root)) { System.out.println(name + " ended job"); return; } System.out.println(name + " get tree and searching..."); node = model.findNode(root, tester); if (node != null) break; System.out.println("For that time there are no nodes, " + name + " waiting..."); try { tree.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } System.out.println(name + " found node " + node); nodeName = node.toString(); nodeNum = Integer.parseInt(nodeName); model.setData(node, this.name + " start with " + nodeName); updateTree(); } System.out.println(name + " handling " + nodeName); nodeNum = (int)(nodeNum > 47 ? 47-Math.random() * 7 : nodeNum < 20 ? 20 : nodeNum); fibo(nodeNum); System.out.println(name + " handled " + nodeName); synchronized (tree) { model.setData(node, name + " finished with " + nodeName); updateTree(); tree.notifyAll(); } } } private boolean isNumber(Object node) { try { Integer.parseInt(node.toString()); return true; } catch (Exception e) { return false; } } public boolean isFinished(Object node) { return node.toString().indexOf("finish") >= 0; } public int fibo(int n) { if (n <= 0) return 0; else if (n == 1 || n == 2) return n; else return fibo(n-1) + fibo(n-2); } Predicate<Node> tester = (node)->{ if (!isNumber(node)) return false; Iterator<Node> itr = model.iterator(node); itr.next(); while (itr.hasNext()) { if (!isFinished(itr.next())) return false; } return true; }; void updateTree() { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { tree.updateUI(); } }); } } This code is intended to demonstrate how multithreading works in Java. But, as far as I understand, the synchronized(tree) block indicates that the JTree component will be processed only by one thread at a time, which in this case excludes the expediency of using several threads to process this tree. Is it possible to somehow change this code so that synchronized or its analogue can restrict access of one stream to only one node, and not to the whole tree?
