public class RegularTree extends BinaryTree {

    public CompleteTree() {
        super();
    }

    public void insert(Comparable item) {
        if(this.isEmpty()) {
            this.setRoot(new TreeNode(item));
            return;
        }

        TreeNode p = null;
        TreeNode q = this.getRoot();
        while(q != null) {
            p = q;
            if(p.getLeft() == null)
                q = p.getLeft();
            else if(p.getRight() == null)
                q = p.getRight();
            else
                q = p.getLeft();
        }
        p.setValue(new TreeNode(item));
    }

    public void inorder() {
        doInorderTraversal(this.getRoot());
    }

    private void doInorderTraversal(TreeNode t) {
        if(t != null) {
            doInorderTraversal(t.getLeft());
            System.out.print(t.getValue() + " ");
            doInorderTraversal(t.getRight());
        }
    }

}

public static void main(String[] args) {
    BinaryTree tree = new CompleteTree();
    tree.insert(1);
    tree.insert(2);
    tree.insert(3);
    tree.insert(4);
    tree.insert(5);
    tree.insert(6);
    tree.inorder();
}