Question

我需要为我的Java数据结构类创建一个二叉树。我还是比较新的，所以请原谅任何新手的错误。我的Btree需要包含String类型的节点。我的问题是我可以添加一个名称，但当我去添加第二个名称时，我的程序崩溃了，我得到以下错误。

Exception in thread "main" java.lang.StackOverflowError
at java.lang.Character.toUpperCase(Unknown Source)
at java.lang.Character.toUpperCase(Unknown Source)
at java.lang.String$CaseInsensitiveComparator.compare(Unknown Source)
at java.lang.String$CaseInsensitiveComparator.compare(Unknown Source)
at java.lang.String.compareToIgnoreCase(Unknown Source)

这是我的代码：

BTNode

public class BTNode {

private String word;
private BTNode rPoint, lPoint;

public BTNode(String pWord){
    word = pWord;
    rPoint = null;
    lPoint = null;
}

public void setWord(String pWord){
    word = pWord;
}

public String getWord(){
    return word;
}

public void setRight(BTNode pRight){
    rPoint = pRight;
}

public BTNode getRight(){
    return rPoint;
}

public void setLeft(BTNode pLeft){
    lPoint = pLeft;
}

public BTNode getLeft(){
    return lPoint;
    }
}

B树

public class BTree {

private BTNode root;

    public void setRoot(BTNode pRoot){
        root = pRoot;
    }

    public BTNode getRoot(){
        return root;
    }

    public BTNode addOne(BTNode pRoot, String pName){
        if(pRoot == null){
            BTNode temp = new BTNode(pName);
            pRoot = temp;
            temp.setWord(pName);
        }else if(pName.compareToIgnoreCase(pRoot.getWord()) > 0){
            pRoot.setLeft(addOne(pRoot, pName));
        }else if(pName.compareToIgnoreCase(root.getWord()) < 0){
            pRoot.setRight(addOne(pRoot, pName));
        }
        return pRoot;
    }

    public void displayAll(BTNode current){
        if(current != null){
            displayAll(current.getLeft());
            System.out.println(current.getWord());
            displayAll(current.getRight());
        }
    }

    public BTNode BTSearch(BTNode pRoot, String pName){
        BTNode found = null;
        if(pRoot == null){
            found = null;
        }else{
            if(pName.equalsIgnoreCase(pRoot.getWord())){
                found = pRoot;
            }
            else if(pName.compareToIgnoreCase(root.getWord()) < 0){
                found = BTSearch(root.getLeft(), pName);
            }else{
                found = BTSearch(root.getRight(), pName);
            }
        }return found;
    }
}

BTreeUser

import java.util.Scanner;

public class BTreeUser {

public static void main(String []args){

    int select = 0;
    BTree tree = new BTree();

    do{
        dispMenu();
        select = getSelection();
        proChoice(select, tree);
    }while(select != 0);

}


    public static void dispMenu(){
        System.out.println("\n|*******************************|");
        System.out.println("|-------------------------------|");
        System.out.println("|************Welcome************|");
        System.out.println("|                               |");
        System.out.println("|  Press [1] to add an entry    |");
        System.out.println("|                               |");
        System.out.println("|  Press [2]|to search          |");
        System.out.println("|                               |");
        System.out.println("|  Press [3] to display all     |");
        System.out.println("|                               |");
        System.out.println("|  Press [0] to exit            |");
        System.out.println("|                               |");
        System.out.println("|Make selection and press[ENTER]|");
        System.out.println("|-------------------------------|");
        System.out.println("|*******************************|\n");
    }

    public static int getSelection(){
        Scanner input = new Scanner(System.in);
        int selection = input.nextInt();
        return selection;
    }

    public static String inputWord(int select){
        Scanner input = new Scanner(System.in);
        String lName = null;
        if(select == 1){
        System.out.println("Please input word now: ");
        lName = input.nextLine();
    }else if(select == 2){
        System.out.println("Please input word to search for now: ");
        lName = input.nextLine();

        }
        return lName;
    }

    public static  void proChoice(int select, BTree tree){
        String pName;
        switch(select){
        case 1: pName = inputWord(select);
                tree.setRoot(tree.addOne(tree.getRoot(), pName));
                break;
        case 2: pName = inputWord(select);
                tree.BTSearch(tree.getRoot(), pName);
                break;
        case 3: tree.displayAll(tree.getRoot());
                break;
        case 0: System.out.println("Thank you, come again...");
                break;
        }

    }
}

我知道我的addOne方法错误发生在BTree。我不确定我是否正确使用compareToIgnoreCase。对于我如何解决这个或我需要做出的任何改变的任何帮助或建议将不胜感激。

Answer 1

该方法使用与收到的完全相同的参数调用自身：

 pRoot.setLeft(addOne(pRoot, pName));

由于输入没有任何变化，任何事情都无法改变，递归是无限的。

修复：

pRoot.setLeft(addOne(pRoot.getLeft(), pName));

正确的分支也是如此。

二进制树使用字符串并在添加节点时遇到问题

1 个答案: