这是一个程序，它接受一个文本文件（.txt，而不是Microsoft word或pdf的东西，只是一个基本的文本文件）作为命令行参数并存储每个单词（接受所有标点符号就像它是一个空间字符，包括二叉树中的撇号。树中的每个节点都存储一个ArrayList，它保存单词出现的次数（第一个元素）和文本文件中出现的每个位置（所有后续元素）。将向用户显示单词总数，您可以搜索单词以查看文件存储的次数和位置。
代码不是我的，autor是MasudKhan，我正在学习如何为类似的程序做我自己的代码。
我在使用此代码查找错误以及它无法正常工作时遇到了一些问题，错误消息是：
＆＃34;线程中的异常＆＃34; main＆＃34; java.lang.ArrayIndexOutOfBoundsException：0 在A3Driver.main（A3Driver.java:10）＆＃34;
A3Driver.java
/**
Assignment3
This class is a driver for a program which reads in a file,
whose name is given as a command line argument, and stores each
word as well as how many occurences of that word and the positions of
each occurence in the text file. The program then offers to allow
the user to search for any input word and produce the info for it,
if any.
*/
import java.io.*;
import java.util.*;
public class A3Driver
{
/**
main method for Binary word search program.
*/
public static void main(String[] args)
{
WordBST newTestWordBST = new WordBST(new File(args[0]));
System.out.println("Total number of words in file: " +
WordBST.wordPosition);
System.out.println("Number of unique words in file: " +
WordBST.uniqueWordCount);
System.out.print("Most used word: " + WordBST.mostUsedWord);
System.out.println(", times used: " + WordBST.highestCount);
System.out.println("\n\n");
Scanner keyboard = new Scanner(System.in);
String input = "";
while(!input.equals("n"))
{
System.out.print("Search for word (y/n)? ");
input = keyboard.nextLine();
if(input.toLowerCase().equals("y"))
{
System.out.print("Enter word: ");
newTestWordBST.searchBinaryTree(keyboard.nextLine());
}
}
System.out.println("Thank you, goodbye.");
/**
To output all tree info, uncomment this section.
newTestWordBST.inOrderTraverse();
*/
}
}
WordBST.java
/**
Assignment3
This class holds a Binary search tree of WordBSTNodes.
*/
import java.io.*;
import java.util.*;
public class WordBST
{
WordBSTNode root;
static int wordPosition, uniqueWordCount = 0, highestCount;
static String mostUsedWord;
/**
Constructor: initializes the root to null.
*/
public WordBST()
{
root = null;
}
/**
Constructor: initializes root to parameter value.
@param theRoot the root of this WordBST object
*/
public WordBST(WordBSTNode theRoot)
{
root = theRoot;
}
/**
Constructor: initializes root to hold nodes containing the words and
data from the parameter file.
@param text the input file containing words
*/
public WordBST(File text)
{
try
{
BufferedReader bR = new BufferedReader(new FileReader(text));
root = readBinaryTree(bR);
}
catch(IOException e)
{
System.out.println("Error reading file. Exiting.");
System.exit(1);
}
}
/**
Wrapper method for the recursive add method.
@param item the item to add to the BST
*/
public void add(String item)
{
root = add(root, item);
}
/**
Postcondition: uses recursion to add item to the BST node in the
appropriate position, or add information to the matching node.
@param localRoot the local node being checked in the current call
@param item the item to add to the BST
*/
private WordBSTNode add(WordBSTNode localRoot, String item)
{
if(localRoot == null) // item not in tree - add it
{
uniqueWordCount++; // total distinct word count
ArrayList<Integer> temp = new ArrayList<Integer>();
temp.add(1);
temp.add(wordPosition);
return new WordBSTNode(item, temp);
}
else if(item.compareTo(localRoot.word) == 0) // item == localRootData
{
localRoot.countAndPos.set(0, localRoot.countAndPos.get(0) + 1);
localRoot.countAndPos.add(wordPosition);
if(localRoot.countAndPos.get(0) > highestCount)
{
highestCount = localRoot.countAndPos.get(0);
mostUsedWord = localRoot.word;
}
return localRoot;
}
else if(item.compareTo(localRoot.word) < 0) //item < localRootData
{
localRoot.leftTree = add(localRoot.leftTree, item);
return localRoot;
}
else // item > localRootData
{
localRoot.rightTree = add(localRoot.rightTree, item);
return localRoot;
}
}
/**
Postcondition: performs an inorder traversal.
*/
public void inOrderTraverse()
{
inOrderTraverse(root);
}
/**
Perform an inorder traversal.
@param localRoot the current node being traversed
*/
private void inOrderTraverse(WordBSTNode localRoot)
{
if(localRoot.leftTree != null) // left
{
inOrderTraverse(localRoot.leftTree);
}
// middle
//output current root
System.out.print(localRoot.word);
for(int i = 0; i < localRoot.countAndPos.size(); i++)
{
System.out.print(", " + localRoot.countAndPos.get(i));
}
System.out.println();
if(localRoot.rightTree != null) // right
{
inOrderTraverse(localRoot.rightTree);
}
}
/**
Wrapper method for searchBinaryTree recursive method.
@param searchWord the String word to search for
*/
public void searchBinaryTree(String searchWord)
{
searchBinaryTree(searchWord, root);
}
/**
Postcondition: if word is found in the search, it is output along with
occurrence information, and if it is not found, not-found info is output.
@param searchWord the word to search for
@param localRoot the localRoot being checked in the current call
*/
public void searchBinaryTree(String searchWord, WordBSTNode localRoot)
{
if( (searchWord.compareTo(localRoot.word) < 0) &&
(localRoot.leftTree != null) )
{
searchBinaryTree(searchWord, localRoot.leftTree);
}
else if( (searchWord.compareTo(localRoot.word) > 0) &&
(localRoot.rightTree != null) )
{
searchBinaryTree(searchWord, localRoot.rightTree);
}
else if(searchWord.compareTo(localRoot.word) == 0)
{
System.out.println("Position number(s) of occurence(s):");
for(int i = 1; i < localRoot.countAndPos.size(); i++)
{
System.out.println("word #" + localRoot.countAndPos.get(i));
}
System.out.println("Word found.");
System.out.println("Occurences: " +
localRoot.countAndPos.get(0));
}
else
{
System.out.println("Word does not exist.");
}
}
/**
@param bR the bufferedReader to read from
@return returns a node containing the info from the file which the input
BufferedReader is reading from
*/
public WordBSTNode readBinaryTree(BufferedReader bR)
{
String data = "";
String temp;
try
{
while(bR.ready())
{
data = data.concat(bR.readLine().toLowerCase() + "\n");
}
if(data == "")
{
return null;
}
}
catch(IOException e)
{
System.out.println("Error reading file. Exiting.");
System.exit(1);
}
return readBinaryTree(
new StringTokenizer(data,
" \t\n\r\f.,!`'-\"\\:()[]{}=+_*&^%$#@?<>;|/~"));
}
/**
@param inputST the StringTokenizer to repeatedly add words from
@return returns a node containing the info from the file which the input
BufferedReader is reading from
*/
public WordBSTNode readBinaryTree(StringTokenizer inputST)
{
wordPosition = 1;
ArrayList<Integer> tempArrayList =
new ArrayList<Integer>(wordPosition++);
tempArrayList.add(1);
WordBST tempBST = new WordBST(
new WordBSTNode(inputST.nextToken(), tempArrayList));
highestCount = 1;
mostUsedWord = tempBST.root.word;
while(inputST.hasMoreTokens())
{
tempBST.add(inputST.nextToken());
wordPosition++; // current position, and total words in file
}
return tempBST.root;
}
}
WordBSTNode.java
/**
Assignment3
This class holds a node for a binary search tree. The node includes
a pointer to it's left subtree and it's right subtree, as well as String
data, and an ArrayList containing the number of occurences of the
data in the user's input file in the first position, followed by the
word number in each following position.
*/
import java.util.*;
public class WordBSTNode
{
WordBSTNode leftTree;
WordBSTNode rightTree;
String word;
ArrayList<Integer> countAndPos;
/**
Constructor: no arg constructor must never be used to avoid
confusion between a null node element and a null element content.
*/
public WordBSTNode()
{
System.out.println("Cannot creat empty node, sorry.");
}
/**
Constructor: initializes parent, word, and countAndPos instance
variables.
@param theWord the word to be stored in this node
@param theCountAndPos an ArrayList containing this node's word's
count and position's
*/
public WordBSTNode(String theWord, ArrayList<Integer> theCountAndPos)
{
leftTree = null;
rightTree = null;
word = theWord;
countAndPos = theCountAndPos;
}
}
任何帮助都是非常有用的。