創建一個鏈接列表

Question

我的程序是爲了獲取單詞列表並將每個單詞按照升序存儲在數組中的字母引用下。例如A-Z單詞蘋果的數組，A下的一個鏈接列表下的A被0引用，Zebra下的Z被引用25.但是當我使用標準的first = new Node（單詞）時，我沒有添加任何內容。我絕望地迷失了。

import java.util.LinkedList; 
public class ArrayLinkedList 
{  
    /** 
    The Node class is used to implement the 
    linked list. 
    */ 

    private class Node 
    { 
     String value; 
     Node next; 

     /** 
     * Constructor 
     * @param val The element to store in the node 
     * @param n The reference to the successor node 
     */ 
     Node(String val, Node n) 
     { 
     value = val; 
     next = n; 
     } 
     Node(String val) 
     { 
      this(val, null); 
     } 
    }  

    private final int MAX = 26; // Number of nodes for letters 
    private Node first;   // List head 
    private Node last;   // Last element in the list 
    private LinkedList[] alpha; // Linked list of letter references 

    /** 
    * Constructor to construct empty array list 
    */ 

    public ArrayLinkedList() 
    { 
     first = null; 
     last = null; 
     alpha = new LinkedList[MAX]; 

     for (int i = 0; i < MAX; i++) 
     { 
      alpha[i] = new LinkedList(); 
     } 
    } 

    /** 
    * arrayIsEmpty method 
    * To check if a specified element is empty 
    */ 
    public boolean arrayIsEmpty(int index) 
    { 
     return (alpha[index].size() == 0); 
    } 

    /** 
    * The size method returns the length of the list 
    * @return The number of elements in the list 
    */ 
    public int size() 
    { 
      int count = 0; 
      Node p = first; 
      while (p != null) 
      { 
       // There is an element at p 
       count++; 
       p = p.next; 
      } 
      return count; 
    }  

    /** 
    * add method 
    * Adds the word to the first position in the linked list 
    */ 
    public void add(String e) 
    { 
     String word = e.toLowerCase(); // Put String to lowercase 
     char c = word.charAt(0);  // to get first letter of string 
     int number = c - 'a';   // Index value of letter 

     // Find position of word and add it to list 
     if (arrayIsEmpty(number)) 
     { 
      first = new Node(word); 
      first = last; 
     } 
     else 
     { 
      first = sort(first, word, number); 
     }  
    } 

    /** 
    * nodeSort method 
    * To sort lists 
    */ 
    private Node sort(Node node, String value, int number) { 
     if (node == null) // End of list 
     { 
      return getNode(value, number); 
     } 
     int comparison = node.value.compareTo(value); 
     if (comparison >= 0) // Or > 0 for stable sort. 
     { 
      Node newNode = getNode(value, number); // Insert in front. 
      newNode.next = node; 
      return newNode; 
     } 
     node.next = sort(node.next, value, number); // Insert in the rest. 
     return node; 
} 

    private Node getNode(String value, int number) 
    { 
     return first.next; 
    } 
    /** 
    * get method 
    * to get each word value from the linked list and return it 
    * @return value 
    */ 

    public LinkedList get(int index) 
    { 
     return alpha[index]; 
    } 

    public String toString() 
    { 
     StringBuilder sBuilder = new StringBuilder(); 

     sBuilder.append("Word and occurrence in ascending order\n\n"); 

     Node p = first; 

     while (p != null) 
     { 
      sBuilder.append(p.value + "\n");    
      p = p.next; 
     } 
     return sBuilder.toString();  
    } 
} 

Answer 1

你有這樣做的原因嗎？ 我可以想出一個更簡單的方法：使用Map將一個字符（例如「A」）映射到Words的LinkedList。