java实现AVL树

public class AVLTree<T extends Comparable>{
public T data;
public AVLTree<T> left;
public AVLTree<T> right;
public int bf;
private static boolean taller;

public AVLTree(){

}

public AVLTree(T[] array){
AVLTree<T> pre=new AVLTree<T>();
for(T ele:array){
try{
insert(pre,pre.left,true,ele);
this.data=pre.left.data;
this.left=pre.left.left;
this.right=pre.left.right;
}catch(Exception e){
System.out.println(e.getMessage());
}finally{

}
}
}
private void LRotate(AVLTree<T> parent,AVLTree<T> current,boolean isLeft){
AVLTree<T> right=current.right;
current.right=right.left;
right.left=current;
if(isLeft)
parent.left=right;
else
parent.right=right;
}

private void RRotate(AVLTree<T> parent,AVLTree<T> current,boolean isLeft){
AVLTree<T> left=current.left;
current.left=left.right;
left.right=current;
if(isLeft)
parent.left=left;
else
parent.right=left;
}

private void leftBalance(AVLTree<T> parent,AVLTree<T> current,boolean isLeft){
AVLTree<T> left=current.left;
switch(left.bf){
case 1:
RRotate(parent,current,isLeft);
left.bf=0;
current.bf=0;
break;
case -1:
AVLTree<T> lRight=left.right;
switch(lRight.bf){
case 1:
left.bf=0;
current.bf=-1;
break;
case 0:
left.bf=current.bf=0;
break;
case -1:
left.bf=1;
current.bf=0;
break;
}
lRight.bf=0;
LRotate(current,current.left,true);
RRotate(parent,current,isLeft);
}
}

private void rightBalance(AVLTree<T> parent,AVLTree<T> current,boolean isLeft){
AVLTree<T> right=current.right;
switch(right.bf){
case -1:
RRotate(parent,current,isLeft);
right.bf=0;
current.bf=0;
break;
case 1:
AVLTree<T> rLeft=right.left;
switch(rLeft.bf){
case 1:
right.bf=1;
current.bf=0;
break;
case 0:
right.bf=current.bf=0;
break;
case -1:
right.bf=0;
current.bf=-1;
break;
}
rLeft.bf=0;
RRotate(current,current.right,false);
LRotate(parent,current,true);
}
}

public boolean insert(AVLTree<T> pre,AVLTree<T> p,boolean isLeft,T ele) throws Exception{/*规定实参 pre不能为空，根节点的pre规定为data域为null的AVLTree实例*/
if(pre==null){
throw new Exception("Bad Parameter [pre]");
}
if(p==null){
AVLTree<T> node=new AVLTree();
node.data=ele;
AVLTree<T> n=(isLeft)?(pre.left=node):(pre.right=node);/*n没有用，只是满足条件选择运算符的语法要求*/
taller=true;
return true;                /*不存在相同元素则插入成功*/
}else{
if(p.data.compareTo(ele)==0){
taller=false;
return false;/*存在相同元素返回false*/
}
if(p.data.compareTo(ele)>0){
boolean isSuccess=insert(p,p.left,true,ele);
if(!isSuccess){
taller=false;
return false;
}
if(taller){
switch(p.bf){
case 0:
p.bf=1;
taller=true;
break;
case 1:
leftBalance(pre,p,isLeft);
taller=false;
break;
case -1:
p.bf=0;
taller=false;
break;
}
}
return true;
}else{
boolean isSuccess=insert(p,p.right,false,ele);
if(!isSuccess){
taller=false;
return false;
}
if(taller){
switch(p.bf){
case 0:
p.bf=-1;
taller=true;
break;
case 1:
p.bf=0;
taller=false;
break;
case -1:
rightBalance(pre,p,isLeft);
taller=false;
break;
}
}
return true;
}
}

}

public String inOrderTraverse(AVLTree<T> root){
if(root!=null){
return inOrderTraverse(root.left)+root.data.toString()+","+inOrderTraverse(root.right);
}else
return "";
}

public String toString() {
String string=inOrderTraverse(this);
string=string.substring(0, string.length()-1);
return "AVLTree [" + string + "]";
}

public static void main(String[] args){
Integer[] array=new Integer[]{4,7,9,3,1,6,5,2,8,0};
AVLTree<Integer> avl=new AVLTree<>(array);
System.out.println(avl);
}
}