無論我嘗試在無法解決顯示java.lang.NullPointerException
與框架類結果行
bTree.binaryTree[i].Data=in.nextLine();
做輸入節點的二叉樹數:異常在 線程「主「java.lang.NullPointerException節點#0的詳細信息,位於 binaryTree.framework.intialize(framework.java:19)輸入數據:at binaryTree.main.main(main.java:9)以退出代碼1結束的進程
Gith UB要點:https://gist.github.com/D-codex/0051d59abb91fafc73fbec0fa7dad356
編輯:https://gist.github.com/D-codex/009a5afa391c760b7ecc88f8109662c0
(以下GhostCat的建議後),我已經做了我最好的初始化幾乎所有的東西,以避免「空」任何地方,但這個例外不斷彈出
節點類
package binaryTree;
import java.util.*;
public class node {
boolean hasLeft,hasRight;
boolean isRootPrimary,isRoot;
String Data;
String nodeID,leftNodeID,rightNodeID,parentID;
int childrenNodeCount;
node(){
hasLeft=false;
hasRight=false;
Data="";
childrenNodeCount=0;
}
void check(){
if(hasLeft||hasRight)
isRoot=true;
}
String fetchRoot(){
return parentID;
}
String fetchID(){
return nodeID;
}
String fetchSiblingID(){
return "("+String.valueOf(leftNodeID)+" "+String.valueOf(rightNodeID)+")";
}
}
樹類
package binaryTree;
import java.util.*;
public class Tree extends node{
node binaryTree[];
int count;int rootID,height,depth;
String siblingPairs,leaves;
Tree(int count){
binaryTree=new node[count];
this.count=count;
rootID=0;
height=0;depth=0;
}
void finalise(){
for(int i=0;i<count;i++){
if(binaryTree[i].childrenNodeCount==0)
leaves=String.valueOf(binaryTree[i].fetchID());
if(binaryTree[i].childrenNodeCount==2){
siblingPairs=binaryTree[i].fetchSiblingID();
}
}
StringTokenizer st=new StringTokenizer(leaves);
while(st.hasMoreElements()){
int counter=0;
int leafID=Integer.valueOf(st.nextToken());
node temp=binaryTree[leafID];
while(temp.isRootPrimary){
temp=binaryTree[Integer.valueOf(temp.fetchRoot())];
counter=counter+1;
}
if(counter>height) {
height = counter;
depth=height-1;
}
}
}
}
框架類
package binaryTree;
import java.util.*;
public class framework {
public Tree intialize(){
System.out.print("Enter the Number of Nodes in the Binary Tree :");
Scanner in=new Scanner(System.in);
int count=in.nextInt();
Tree bTree=new Tree(count);
int ID=0;int i=0;
while(i<count){
System.out.println("Details for node#"+i);
System.out.print("Enter Data :");
bTree.binaryTree[i].Data=in.nextLine();
bTree.binaryTree[i].nodeID=String.valueOf(ID);
if(i!=0){
boolean flag = true;
while (flag) {
String parentID="";
System.out.print("Enter the node's Parent:");
parentID = in.nextLine();
if (bTree.binaryTree[Integer.valueOf(parentID)].childrenNodeCount >= 2) {
System.out.println("Parent Node is Full");
}
else {
bTree.binaryTree[i].parentID = in.nextLine();
bTree.binaryTree[Integer.valueOf(parentID)].childrenNodeCount=bTree.binaryTree[Integer.valueOf(parentID)].childrenNodeCount+1;
flag=false;
}
}
System.out.print("Is the node Parent's Left?");
String temp=in.next();
if(temp.equalsIgnoreCase("yes")||temp=="1"||temp.equalsIgnoreCase("y")){
bTree.binaryTree[Integer.valueOf(bTree.binaryTree[i].parentID)].hasLeft=true;
bTree.binaryTree[Integer.valueOf(bTree.binaryTree[i].parentID)].leftNodeID=bTree.binaryTree[i].nodeID;
}
else {
bTree.binaryTree[Integer.valueOf(bTree.binaryTree[i].parentID)].hasRight = true;
bTree.binaryTree[Integer.valueOf(bTree.binaryTree[i].parentID)].rightNodeID=bTree.binaryTree[i].nodeID;
}
}
else
bTree.binaryTree[i].isRootPrimary=true;
bTree.binaryTree[i].check();
i=i+1;ID=ID+1;
}
bTree.finalise();
return bTree;
}
public void displayAll(Tree bTree){
System.out.println("Running a Full Analysis on the Binary Tree");
System.out.println("Printing nodes Details");
for(int i=0;i<bTree.count;i++){
System.out.println("Node #"+i);
System.out.println("PrimaryRoot :"+bTree.binaryTree[i].isRootPrimary);
System.out.println("isRoot :"+bTree.binaryTree[i].isRoot);
System.out.println("Data :"+bTree.binaryTree[i].Data);
System.out.println("Number of Children Nodes :"+bTree.binaryTree[i].childrenNodeCount);
System.out.println("hasLeft :"+bTree.binaryTree[i].hasLeft);
if(bTree.binaryTree[i].hasLeft)
System.out.println("LeftNodeID :"+bTree.binaryTree[i].leftNodeID);
System.out.println("hasRight :"+bTree.binaryTree[i].hasRight);
if(bTree.binaryTree[i].hasRight)
System.out.println("RightNodeID :"+bTree.binaryTree[i].rightNodeID);
System.out.println("parentID :"+bTree.binaryTree[i].fetchRoot());
System.out.println("SiblingPairs (if any) :"+bTree.binaryTree[i].fetchSiblingID());
System.out.println("____________________________________________________________________________");
}
System.out.println("Tree Specifications");
System.out.println("Total No. of Nodes :"+bTree.count);
System.out.println("Height of Tree :"+bTree.height);
System.out.println("Depth of Tree :"+bTree.depth);
System.out.println("Leaves :"+bTree.leaves);
System.out.println("Sibling Pairs :"+bTree.siblingPairs);
}
}
主類
package binaryTree;
public class main {
public static void main(String Args[]){
framework Framework=new framework();
Tree binaryTree=Framework.intialize();
Framework.displayAll(binaryTree);
}
}
可能重複[什麼是NullPointerException,以及如何解決它?](http://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-doi-i-fix -it) –
遵循java命名約定,如果你不知道,請閱讀它。 –
感謝您的快速接受。當我下週找到時間時,我會爲你提出一些建議。 – GhostCat