avl tree implementation in java

 avl tree implementation in java

public class avlTree {
    class Node{
        int data;
        Node left;
        Node right;
        int height;
        Node(int data){
            this.data=data;
            this.left=null;
            this.right=null;
            this.height=0;
        }
    }
    public int getheight(Node n){
        if (n==null) return -1;
        int lh=getheight(n.left);
        int rh=getheight(n.right);
        int fh=Math.max(lh,rh)+1;
        return fh;
    }
    public int getbalancefac(Node n){
        if (n==null) return 0;
        return getheight(n.left)-getheight(n.right);
    }
    public  Node rightRotate(Node a){
        Node b=a.left;
        Node br=b.right;
        b.right=a;
        a.left=br;
        a.height=Math.max(getheight(a.left),getheight(a.right))+1;
        b.height=Math.max(getheight(b.left),getheight(b.right))+1;
        return b;
    }
    public Node leftRotate(Node a){
        Node b=a.right;
        Node bl=b.left;
        b.left=a;
        a.right=bl;
        a.height=Math.max(getheight(a.left),getheight(a.right))+1;
        b.height=Math.max(getheight(b.left),getheight(b.right))+1;
        return b;
    }
    public Node insert(Node root,int value){
        if (root==null) return new Node(value);
        if (value<root.data){
            root.left=insert(root.left,value);
        }
        else if (value>root.data){
            root.right=insert(root.right,value);
        }
        root.height=Math.max(getheight(root.left),getheight(root.right))+1;
        int bf=getbalancefac(root);
        //LL
        if (bf>1 && value < root.left.data){
            return rightRotate(root);
        }
        //RR
        if (bf<-1 && value >root.right.data){
            return leftRotate(root);
        }
        //LR
        if (bf>1 && value>root.left.data){
            root.left=leftRotate(root.left);
            return rightRotate(root);
        }
        //RL
        if (bf<-1 && value<root.right.data){
            root.right=rightRotate(root.right);
            return leftRotate(root);
        }
        return root;
    }
public void display(Node n){
        if (n==null) return;;
        String str="";
        if (n.left==null){
            str+=".";
        }
        else {
            str+=n.left.data;
        }
        str+=">="+n.data+"<=";
        if (n.right==null){
            str+=".";
        }
        else {
            str+=n.right.data;
        }
    System.out.println(str);
        display(n.left);
        display(n.right);
}
    public static void main(String[] args) {
        avlTree avv=new avlTree();
        Node root=null;
        root=avv.insert(root,55);
        root=avv.insert(root,45);
        root=avv.insert(root,65);
        root=avv.insert(root,43);
        root=avv.insert(root,100);
        root=avv.insert(root,200);
        avv.display(root);

    }

}