本文執行個體講述了Java實作二叉樹的建立、計算高度與遞歸輸出操作。分享給大家供大家參考，具體如下：
1. 建立 遞歸輸出 計算高度 前中後三種非遞歸輸出
public class Tree_Link {
private int save = 0;
private int now = 0;
Scanner sc = new Scanner(System.in);
Tree_Link(){
}
public Tree Link_Build(Tree head){
// Tree head = new Tree();//頭節點
System.out.println("繼續code：1");
int flag = sc.nextInt();
if(flag != 1){
return head;
}else{
System.out.println("\n\n\n輸入 節點資訊：");
head.SetCode(sc.nextInt());
System.out.println("\n建立 左 子樹code：1 否則：0");
flag = sc.nextInt();
if(flag == 1){
now++;
Tree LTree = new Tree();
head.SetLtree(LTree);
LTree.SetFronttree(head);//設定父母節點
Link_Build( head.GetLtree() );
}
System.out.println("\n目前位置：" + head.GetCode());
System.out.println("\n建立 右 子樹code：1 否則：0");
flag = sc.nextInt();
if(flag == 1){
now++;
Tree Rtree = new Tree();
head.SetRtree(Rtree);
Rtree.SetFronttree(head);//設定父母節點
Link_Build( head.GetRtree() );
}
if( now > save ){
save = now;
}
now--;
}
return head;
}
public Tree output(Tree head){
int flag;
if(head.GetCode() == -1){
return head;
}else{
System.out.println("\n目前位置：" + head.GetCode());
System.out.println(head.GetLtree() != null);
if(head.GetLtree() != null){
System.out.println("\n通路 左子樹:");
output( head.GetLtree() );
}
if(head.GetRtree() != null){
System.out.println("\n通路 右子樹:");
output( head.GetRtree() );
}
}
return head;
}
public int GetSave(){
return this.save;
}
public void Front_Traverse(Tree head){
Tree star = head;//退出标記
int choose = 1; //左
int flag = 1; //右
System.out.println( "" + head.GetCode() );//先通路根
while(true){
if( head.GetLtree() != null && choose != 0 ){
head = head.GetLtree();
System.out.println( "" + head.GetCode() );//獲得資訊
flag = 1;
}else if( head.GetRtree() != null && flag != 0 ){
head = head.GetRtree();
System.out.println( "" + head.GetCode() );
choose = 1;
}else if( flag == 0 && choose == 0 && head == star){
break;
}else{
if(head == head.GetFronttree().GetRtree()){
flag = 0;
choose = 0;
}
if(head == head.GetFronttree().GetLtree()){
choose = 0;
flag = 1;
}
head = head.GetFronttree();
System.out.println("獲得 父母" + head.GetCode());
System.out.println( "\n\n\n" );
}
}
}
public void Center_Traverse(Tree head){
Tree star = head;//退出标記
int choose = 1; //左
int flag = 1; //右
while(true){
if( head.GetLtree() != null && choose != 0 ){
head = head.GetLtree();
flag = 1;
}else if( head.GetRtree() != null && flag != 0 ){
if(head.GetLtree() == null){//因為左邊為空而傳回
System.out.println( "" + head.GetCode());
}
head = head.GetRtree();
choose = 1;
}else if( flag == 0 && choose == 0 && head == star){
break;
}else{
int area = 0;//判斷哪邊回來
flag = 1;
choose = 1;
if(head == head.GetFronttree().GetRtree()){
area = 1;//右邊回來
flag = 0;
choose = 0;
}
if(head == head.GetFronttree().GetLtree()){
area = 2;//左邊回來
choose = 0;
flag = 1;
}
if( head.GetLtree() == null && head.GetRtree() == null ){//因為左邊為空而傳回
System.out.println( "" + head.GetCode());
}
head = head.GetFronttree();
if( area == 2){//因為左邊通路完傳回
System.out.println( "" + head.GetCode());
}
System.out.println("獲得 父母" + head.GetCode());
System.out.println( "\n\n\n" );
}
}
}
public void Bottom_Traverse(Tree head){
Tree star = head;//退出标記
int choose = 1; //左
int flag = 1; //右
while(true){
if( head.GetLtree() != null && choose != 0 ){
head = head.GetLtree();
flag = 1;
}else if( head.GetRtree() != null && flag != 0 ){
head = head.GetRtree();
choose = 1;
}else if( flag == 0 && choose == 0 && head == star){
break;
}else{
int area = 0;//判斷哪邊回來
flag = 1;
choose = 1;
if(head == head.GetFronttree().GetRtree()){
area = 1;//右邊回來
flag = 0;
choose = 0;
}
if(head == head.GetFronttree().GetLtree()){
choose = 0;
flag = 1;
}
if(head.GetRtree() == null){//因為右邊為空而傳回
System.out.println( "" + head.GetCode());
}
head = head.GetFronttree();
if( area == 1){
System.out.println( "" + head.GetCode());
}
System.out.println("獲得 父母" + head.GetCode());
System.out.println( "\n\n\n" );
}
}
}
}
2. Tree 類實作：
public class Tree {
private int code = -1;
private Tree Fonttree;
private Tree Ltree;
private Tree Rtree;
Tree(){
this.code = -1;
this.Ltree = null;
this.Rtree = null;
}
public void SetCode(int code){//設定編号
this.code = code;
}
public int GetCode(){ //擷取編号
return this.code;
}
public void SetFronttree(Tree Front){
this.Fonttree = Front;
}
public Tree GetFronttree(){
System.out.println("獲得 父母");
return this.Fonttree;
}
public void SetLtree(Tree Ltree){
this.Ltree = Ltree;
}
public Tree GetLtree(){
System.out.println("獲得左子樹");
return this.Ltree;
}
public void SetRtree(Tree Rtree){
this.Rtree = Rtree;
}
public Tree GetRtree(){
System.out.println("獲得右子樹");
return this.Rtree;
}
}
3. 主函數測試：
public class MainActivity {
Scanner sc = new Scanner(System.in);
public static void main(String[] args) {
Tree head = new Tree();
Tree_Link link_1st = new Tree_Link();
head = link_1st.Link_Build(head);
System.out.println("Build succeed !");
System.out.println("\n二叉樹高度-->" + link_1st.GetSave());
link_1st.output(head);
System.out.println("Output Over !");
System.out.println("\n\n\n前序通路根：");
link_1st.Front_Traverse(head);
System.out.println("\n\n\n中序通路根：");
link_1st.Center_Traverse(head);
System.out.println("\n\n\n後序通路根：");
link_1st.Bottom_Traverse(head);
System.out.println("\n\n\n\nText over !\n\n\n");
}
}
希望本文所述對大家java程式設計有所幫助。