存储单词的具体原理：将单词中的字母a到z分别对应1到26数字，空格为0进行自定义编码。根据编码规则，将单词中的每一个字母对应到相应的数字。利用幂运算得一个数字。比如:cats所对应的数字为

3*27^3+1*27^2+20*27^1+19*27^0=60337

这样得到了一个数值，如果将该值作为数组下标，10个字母的单词就有可能超过7000000000000，数字过于庞大，所以要压缩。为了方便显示，所以我将哈希表的长度设为10，即压缩到0到9范围内。但是又由于long类型范围的限制，最多只能存放长度为7个字母的单词。

下面是源代码

自定义链表节点

/** * define single link list node class */public class LinkedNode { String dataItem; LinkedNode next; public LinkedNode(String data){ this.dataItem = data; } public String getNodeData(){ return dataItem; }}

自定义单向链表

/** * define Link List class */public class SingleLinkedList { private LinkedNode first; private LinkedNode last; int size; //Constructor public SingleLinkedList(){ first = null; last = null; size = 0; } public void insert(LinkedNode linkedNode){ if(first==null){ first = linkedNode; } else { LinkedNode l = last; l.next = linkedNode; } last = linkedNode; size++; } public boolean searchSingleLink(String data){ LinkedNode i = null; for(i =first;i!=null;i=i.next){ if(i.dataItem.equals(data)){ return true; } } if(i==null){ return false; } return false; } public void displaySingleLinkedList(){ for(LinkedNode i = first;i!=null;i=i.next){ System.out.print(i.getNodeData()+"->"); } System.out.println("null"); } @Test public void SingleLinkedTest() { SingleLinkedList singleLinkedList = new SingleLinkedList(); LinkedNode linkedNode = new LinkedNode("a"); singleLinkedList.insert(linkedNode); LinkedNode linkedNode1 = new LinkedNode("b"); singleLinkedList.insert(linkedNode1); singleLinkedList.displaySingleLinkedList(); }}

自定义hash表

public class MyHashTable { int hashArraySize; SingleLinkedList[] hashArray; public MyHashTable(int capacity){ hashArraySize = capacity; hashArray = new SingleLinkedList[hashArraySize]; for(int i = 0;i<hashArraySize;i++){ hashArray[i]=new SingleLinkedList(); } } public void displayHashTable(){ for(int i=0;i<hashArraySize;i++){ System.out.print(i+":");//display cell number hashArray[i].displaySingleLinkedList(); //display list } } /** * * Alphabetical code table * * 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 * * 空格 a b c d e f g h i j k l m n o p q r s t u v w x y z * @param letter * @return */ public int getLetterCode(char letter){ int letterCode = 0; switch (letter){ case 'a': letterCode = 1; break; case 'b': letterCode = 2; break; case 'c': letterCode = 3; break; case 'd': letterCode = 4; break; case 'e': letterCode = 5; break; case 'f': letterCode = 6; break; case 'g': letterCode = 7; break; case 'h': letterCode = 8; break; case 'i': letterCode = 9; break; case 'j': letterCode = 10; break; case 'k': letterCode = 11; break; case 'l': letterCode = 12; break; case 'm': letterCode = 13; break; case 'n': letterCode = 14; break; case 'o': letterCode = 15; break; case 'p': letterCode = 16; break; case 'q': letterCode = 17; break; case 'r': letterCode = 18; break; case 's': letterCode = 19; break; case 't': letterCode = 20; break; case 'u': letterCode = 21; break; case 'v': letterCode = 22; break; case 'w': letterCode = 23; break; case 'x': letterCode = 24; break; case 'y': letterCode = 25; break; case 'z': letterCode = 26; break; } return letterCode; } /** * get hash code of word * @param word * @return */ public int hashFuc(String word){ long oldScope =0; int newScope ; int wordLength = word.length(); for(int i=wordLength-1,j=0;i>=0;i--,j++){ int letterCode = getLetterCode(word.charAt(i)); oldScope += letterCode* Math.pow(27,j ); } newScope = (int)oldScope%10; return newScope; } public void insertIntoHashArray(String word){ LinkedNode linkedNode = new LinkedNode(word); int arrayIndex = hashFuc(word); hashArray[arrayIndex].insert(linkedNode); } public void findWord(String word){ int index = hashFuc(word); boolean b = hashArray[index].searchSingleLink(word); if(b){ System.out.println(word+"在hashTable中存在"); }else { System.out.println(word+"在hashTable中不存在"); } }}

测试

public static void main(String[] args) { MyHashTable myHashTable = new MyHashTable(10); myHashTable.insertIntoHashArray("cats"); myHashTable.insertIntoHashArray("apple"); myHashTable.insertIntoHashArray("and"); myHashTable.insertIntoHashArray("a"); myHashTable.insertIntoHashArray("or"); myHashTable.insertIntoHashArray("contact"); myHashTable.displayHashTable(); myHashTable.findWord("a"); myHashTable.findWord("b"); }

结果