Java/Sorts/BinaryTreeSort.java

package Sorts;

import static Sorts.SortUtils.less;
import static Sorts.SortUtils.print;

/**
 * @author Podshivalov Nikita (https://github.com/nikitap492)
 * @see SortAlgorithm
 */
public class BinaryTreeSort implements SortAlgorithm {

    interface TreeVisitor<T extends Comparable<T>> {
        void visit(Node<T> node);
    }

    private static class SortVisitor<T extends Comparable<T>> implements TreeVisitor<T> {

        private final T[] array;
        private int counter;

        SortVisitor(T[] array) {
            this.array = array;
        }

        @Override
        public void visit(Node<T> node) {
            array[counter++] = node.value;
        }
    }

    private static class Node<T extends Comparable<T>> {
        private T value;
        private Node<T> left;
        private Node<T> right;

        Node(T value) {
            this.value = value;
        }

        void insert(Node<T> node) {
            if (less(node.value, value)) {
                if (left != null) left.insert(node);
                else left = node;
            } else {
                if (right != null) right.insert(node);
                else right = node;
            }
        }

        void traverse(TreeVisitor<T> visitor) {
            if (left != null)
                left.traverse(visitor);

            visitor.visit(this);

            if (right != null)
                right.traverse(visitor);
        }

    }


    @Override
    public <T extends Comparable<T>> T[] sort(T[] array) {

        Node<T> root = new Node<>(array[0]);
        for (int i = 1; i < array.length; i++) {
            root.insert(new Node<>(array[i]));
        }

        root.traverse(new SortVisitor<>(array));

        return array;
    }


    public static void main(String args[]) {

        Integer[] intArray = {12, 40, 9, 3, 19, 74, 7, 31, 23, 54, 26, 81, 12};
        BinaryTreeSort treeSort = new BinaryTreeSort();
        Integer[] sorted = treeSort.sort(intArray);
        print(sorted);

        Double[] decimalArray = {8.2, 1.5, 3.14159265, 9.3, 5.1, 4.8, 2.6};
        print(treeSort.sort(decimalArray));

        String[] stringArray = {"c", "a", "e", "b", "d", "dd", "da", "zz", "AA", "aa", "aB", "Hb", "Z"};
        print(treeSort.sort(stringArray));
    }

}