为什么/在哪里陷入无限循环

Question

I am currently trying to take a text file, and break the text file into words. I am then attempting to store each word as a node in a binary tree. After doing so I also try to print the binary tree. For some reason when i run my code i am now getting caught in an infinite loop but i don't understand where or why that is if you can see where i am getting caught that would be a great help thanks

public class Tester {

public static void main(String[] args) throws FileNotFoundException {

    Tester run = new Tester();
    run.it();

}

public void it() throws FileNotFoundException { 

    BTree theTree = new BTree();

    String str = this.readInFile();

    int position = 0;

    String newWord = this.breakIntoWords(str, position);

    while(newWord != null){

        theTree.add(newWord);

        newWord = this.breakIntoWords(str, position);

    }

    theTree.print();

}

public String readInFile() throws FileNotFoundException {


    String myFile = "";
    int numWords = 0;

    Scanner myScan = new Scanner(new File("Dracula.txt"));

    while(myScan.hasNext() == true) {

        myFile += myScan.nextLine() + " ";

    }

    return myFile;

}

public String breakIntoWords(String myFile, int position) {

    String nextWord = null;

    char next = myFile.charAt(position);
    next = Character.toLowerCase(next);

    // First trim beginning
    while (((next < 'a') || (next > 'z')) && !Character.isDigit(next)) {

        position++;
        next = myFile.charAt(position);
        next = Character.toLowerCase(next);

    }

    // Now pull only letters or numbers until we hit a space
    while(!Character.isWhitespace(next)) {

        if (Character.isLetterOrDigit(next)) {

            nextWord += myFile.charAt(position);

        }

        position++; 
        next = myFile.charAt(position);

    }

    return nextWord;

}

public class BTree {

private BTNode root;
private int nodeCount;


public boolean add(String word){

    BTNode myNode = new BTNode(word);

    if(root == null){

        root = myNode;
        nodeCount++;
        return true;

    }

    if(findNode(word)){

        int tmp = myNode.getNumInstance();
        tmp++;
        myNode.setNumInstance(tmp);
        return false;

    }

    BTNode temp = root;

    while(temp != null){

        if(word.compareTo(temp.getMyWord()) < 0) {

            if(temp.getRightChild() == null){

                temp.setLeftChild(myNode);
                nodeCount++;
                return true;

            } else {

                temp = temp.getRightChild();

            }

        } else {

                if(temp.getLeftChild() == null){

                    temp.setLeftChild(myNode);
                    nodeCount++;
                    return true;

                } else {

                    temp = temp.getLeftChild();

                }

        }

    }

    return false;

}

public boolean findNode(String word) {
    return mySearch(root, word);
}

private boolean mySearch(BTNode root, String word) {
    if (root == null) {
        return false;
    }

    if ((root.getMyWord().compareTo(word) < 0)) {
        return true;
    } else {
        if (word.compareTo(root.getMyWord()) > 0) {
            return mySearch(root.getLeftChild(), word);
        } else {
            return mySearch(root.getRightChild(), word);
        }
    }
}

public void print() {
    printTree(root);
}

private void printTree(BTNode root) {
    if (root == null) {
        System.out.print(".");
        return;
    }

    printTree(root.getLeftChild());
    System.out.print(root.getMyWord());
    printTree(root.getRightChild());

}

public int wordCount() {

    return nodeCount;

}

Answer 1

You repeatedly call this.breakIntoWords(str, position) with the same str and position , using its return value to decide when to stop. Since nothing changes from the one iteration to the next, the loop never terminates.