主要参考<<数据结构与算法分析>>Java语言描述(Mark Allen Weiss)
二叉查找树主要的操作是:1.查找，2，插入，删除。
查找操作：从根节点开始，递归查找。如果值等于当前根节点，返回根节点存储的值。若果查找的值小于跟根节点的值，则查找左子树，反之递归查找右子树。如果要查找的当前节点为NULL，说明查找结束了，没有找到要查找的元素。
插入操作：基本和查找操作相同，只是最后加入找到的是null，则新建一个节点，并返回。
删除操作：找到要删除的节点，让右子树最左边的节点替代。然后删除此节点右子树最小节点。
代码如下：
public class BinarySearchTree<T extends Comparable<? super T>> {
public static void main(String[] args) {
// TODO Auto-generated method stub
BinarySearchTree<Integer> bst = new BinarySearchTree<Integer>();
Integer[] a = {2,45,43,67,8,10,12,43,65,87,432,11,90,48,40};//测试数据
for(int i = 0;i<a.length;i++){
bst.insert(a[i]);
}
bst.remove(45);
bst.remove(12);
bst.showTree();
}
private BinaryNode<T> root;
public static class BinaryNode<T>{
public T element;
public BinaryNode<T> left;
public BinaryNode<T> right;
public BinaryNode(T element, BinaryNode<T> left, BinaryNode<T> right) {
this.element = element;
this.left = left;
this.right = right;
}
public BinaryNode(T theElement) {
element = theElement;
}
}
public BinarySearchTree() {
root = null;
}
public BinarySearchTree(BinaryNode<T> root) {
this.root = root;
}
public boolean isEmpty(){
return root == null;
}
public void makeEmpty(){
root = null;
}
public boolean contains(T x){
return contains(root,x);
}
private boolean contains(BinaryNode<T> root, T x) {
if(root==null){
return false;
}
int comparaResult = x.compareTo(root.element);
if(comparaResult==1){
return true;
}
else if(comparaResult<0){
return contains(root.left,x);
}
else
return contains(root.right,x);
}
public T findMin(){
if(isEmpty()){
try {
throw new Exception();
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return findMin(root).element;
}
public T findMax() throws Exception{
if(isEmpty()){
throw new Exception();
}
return findMax(root).element;
}
private BinaryNode<T> findMin(BinaryNode<T> root) {
if(root==null){
return null;
}
else if(root.left==null){
return root;
}
return findMin(root.left);
}
private BinaryNode<T> findMax(BinaryNode<T> root) {
if(root==null){
return null;
}
else if(root.right==null){
return root;
}
return findMax(root.right);
}
public void insert(T x){
root = insert(x,root);
}
public BinaryNode<T> insert(T x,BinaryNode<T> root){
if(root==null){
return new BinaryNode<T>(x, null, null);
}
int compareResult = x.compareTo(root.element);
if(compareResult>0){
root.right = insert(x,root.right);
}
else if(compareResult<0){
root.left = insert(x,root.left);
}
else
;
return root;
}
public void remove(T a){
remove(a,root);
}
private BinaryNode<T> remove(T x, BinaryNode<T> root2) {
if(root2==null){
return null;
}
int comparaResult = x.compareTo(root2.element);
if(comparaResult < 0){
root2.left = remove(x,root2.left);
}
else if(comparaResult > 0){
root2.right = remove(x,root2.right);
}
else if(root2.left!=null&&root2.right!=null){
root2.element = findMin(root2.right).element;
root2.right = remove(root2.element,root2.right);
}
else{
if(root2.left!=null){
root2 = root2.left;
}
else{
root2 = root2.right;
}
}
return root2;
}
public void showTree(){
showTree(root);
}
public void showTree(BinaryNode<T> T){
if(T==null){
return;
}
else{
showTree(T.left);
System.out.println(T.element);
showTree(T.right);
}
}
}
二叉查找树java实现