我现在正在进行的项目涉及我从文本文件中读取单词并将它们加载到数组中（最终是二叉树，但这将在稍后完成）。我必须将单词和单词的频率（最初为 1）都加载到数组中，因此我将两个变量都打包到一个 objectWordNode中。我能够将单词加载到数组中，但是当我尝试检查单词是否已经在数组中时，事情就崩溃了。如果是，我必须将频率增加 1。我编写了一个新equals()方法来覆盖默认方法，以便比较单词而不是变量引用。但是，我现在收到错误消息Exception in thread "main" java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to [LWordNode;。为什么会出现这种情况？我以为只有WordNode对象被传递给equals().
主要方法：
public class Driver {
/////////////// fields ///////////////
public static ArrayUnorderedList<WordNode> wordArray = new ArrayUnorderedList<WordNode>();
public static LinkedBinarySearchTree<WordNode> wordTree = new LinkedBinarySearchTree<WordNode>(); //tree to hold words
/////////////// methods ///////////////
public static void main(String[] args) throws Exception {
//ask for filename
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the name of the file to read from: ");
Reader file = new FileReader(reader.readLine());
//read file
Scanner input = new Scanner(file);
while(input.hasNext()) {
//get words from file
String word = input.next();
//remove non-word characters and convert to lowercase
word = word.replaceAll("\\W", "");
word = word.toLowerCase();
//create node
WordNode newWord = new WordNode(word);
//if word is already in array
if(wordArray.contains(newWord)) {
System.out.println("Word is already in array");
//increment frequency by 1
int index = wordArray.find(newWord);
wordArray.list[index].setFrequency(wordArray.list[index].getFrequency() + 1);
System.out.println("(" + newWord.getFrequency() + ") " + newWord.getWord());
} else {
System.out.println("Word is not yet in array");
//add word to tree
System.out.println("(" + newWord.getFrequency() + ") " + newWord.getWord());
wordArray.addToRear(newWord);
}
}
//insert into tree
//perform traversals on tree
}
WordNode 类：
public class WordNode {
protected String word;
protected WordNode left, right;
protected int frequency;
/**
* Creates a new node with the specified data.
* @param obj the element that will become a part of the new node
*/
WordNode(String obj) {
word = obj;
left = null;
right = null;
frequency = 1;
}
/**
* Method to check for string equivalence.
* @return true if words are the same
*/
public boolean equals(Object obj) {
WordNode tempWord = (WordNode)obj;
return(tempWord.getWord().equals(this.word));
}
/**
* Gets the word.
* @return the word
*/
public String getWord() {
return word;
}
/**
* Sets the word.
* @param word the word to set
*/
public void setWord(String word) {
this.word = word;
}
/**
* Gets the left.
* @return the left
*/
public WordNode getLeft() {
return left;
}
/**
* Sets the left.
* @param left the left to set
*/
public void setLeft(WordNode left) {
this.left = left;
}
/**
* Gets the right.
* @return the right
*/
public WordNode getRight() {
return right;
}
/**
* Sets the right.
* @param right the right to set
*/
public void setRight(WordNode right) {
this.right = right;
}
/**
* Gets the frequency.
* @return the frequency
*/
public int getFrequency() {
return frequency;
}
/**
* Sets the frequency.
* @param frequency the frequency to set
*/
public void setFrequency(int frequency) {
this.frequency = frequency;
}
}
ArrayList 类的一些方法：
/**
* Returns true if this list contains the specified element.
* @param target the element that the list is searched for
* @return true if the target is in the list, false if otherwise
*/
public boolean contains(T target) {
return (find(target) != NOT_FOUND);
}
/**
* Returns the array index of the specified element, or the
* constant NOT_FOUND if it is not found.
* @param target the element that the list will be searched for
* @return the integer index into the array containing the target element, or the NOT_FOUND constant
*/
public int find(T target) {
int scan = 0, result = NOT_FOUND;
boolean found = false;
if (!isEmpty()) {
while (!found && scan < rear) {
if (target.equals(list[scan])) {
found = true;
} else {
scan++;
}
}
}
if (found) {
result = scan;
}
return result;
}