//before

public class Node {
private Node parent;
private Node left;
private Node right;
private int value;
public void printAllNodes() {
// print node info
}

public void sumAllNodesValues() {
// sum all nodes values
}
}

// after + można wykonywać dowolne opracje na strukturze

interface NodeVisitor {
void visit(Node node);
}
public class PrintNodeVisitor implements
NodeVisitor {

public void visit(Node node) {
System.out.println(node.getValue());
}
}
public class SumNodeVisitor implements
NodeVisitor {

private int sum;

public void visit(Node node) {
sum = sum + node.getValue();
}
}
public class Node {
private Node parent;
private Node left;
private Node right;
private int value;

// move through structure
public void walkThrough(NodeVisitor visitor) {
visitor.visit(value);
if (left != null) {
left.walkThrough(visitor);
}
if (right != null) {
right.walkThrough(visitor);
}
}
public getValue() {
return this.value;
}
}

// tester

class Tester {
public void main(String[] args) {
Node node = intializeNode(); // in this
method structure is created
node.walkThrough(new PrintNodeVisitor());
node.walkThrough(new SumNodeVisitor()

behavioral design patterns