binary tree

package drva;

public class IntTree {

    private static class IntTreeNode {

        private int data;
        private IntTreeNode leftLink;
        private IntTreeNode rightLink;

        public IntTreeNode(int data, IntTreeNode leftLink, IntTreeNode rightLink) {
            this.data = data;
            this.leftLink = leftLink;
            this.rightLink = rightLink;
        }

    }

    private IntTreeNode root;

    public IntTree() {
        root = null;
    }

    public void add(int data) {
        root = insertInSubtree(data, root);
    }

    public boolean contains(int item) {
        return isInSubtree(item, root);
    }

    public void showElements() {
        showElementsInSubtree(root);
    }

    public void showElementsInSubtree(IntTreeNode subRoot) {

        if (subRoot == null) {
            return;
        }

        showElementsInSubtree(subRoot.leftLink);
        System.out.println(subRoot.data + " ");
        showElementsInSubtree(subRoot.rightLink);

    }

    public IntTreeNode insertInSubtree(int data, IntTreeNode subTreeRoot) {
        if (subTreeRoot == null) {
            return new IntTreeNode(data, null, null);
        } else {
            if (data < subTreeRoot.data) {
                subTreeRoot.leftLink = insertInSubtree(data,
                        subTreeRoot.leftLink);
            } else {
                subTreeRoot.rightLink = insertInSubtree(data,
                        subTreeRoot.rightLink);
            }
            return subTreeRoot;
        }
    }

    public boolean isInSubtree(int data, IntTreeNode subTreeRoot) {
        if (subTreeRoot == null) {
            return false;
        } else {
            if (subTreeRoot.data == data) {
                return true;
            } else {
                if (subTreeRoot.data < data) {
                    return isInSubtree(data, subTreeRoot.leftLink);
                } else {
                    return isInSubtree(data, subTreeRoot.rightLink);
                }
            }
        }
    }

}