哈希表的学习java
package ch15; import java.math.BigInteger; public class HashTable { private Info[] arr; /** * 默认的构造方法 */ public HashTable() { arr = new Info[100]; } /** * 指定数组初始化大小 */ public HashTable(int maxSize) { arr = new Info[maxSize]; } /** * 插入数据 */ public void insert(Info info) { arr[hashCode(info.getKey())] = info; } /** * 查找数据 */ public Info find(String key) { return arr[hashCode(key)]; } public int hashCode(String key) { // int hashVal = 0; // for(int i = key.length() - 1; i >= 0; i--) { // int letter = key.charAt(i) - 96; // hashVal += letter; // } // return hashVal; BigInteger hashVal = new BigInteger("0"); BigInteger pow27 = new BigInteger("1"); for(int i = key.length() - 1; i >= 0; i--) { int letter = key.charAt(i) - 96; BigInteger letterB = new BigInteger(String.valueOf(letter)); hashVal = hashVal.add(letterB.multiply(pow27)); pow27 = pow27.multiply(new BigInteger(String.valueOf(27))); } return hashVal.mod(new BigInteger(String.valueOf(arr.length))).intValue(); } } ===================================== package ch15; public class Info { private String key; private String name; public Info(String key,String name){ this.key = key; this.name = name; } public String getKey() { return key; } public void setKey(String key) { this.key = key; } public String getName() { return name; } public void setName(String name) { this.name = name; } } ============================================= package ch15; public class TestHashTable { public static void main(String[] args) { HashTable ht = new HashTable(); ht.insert(new Info("a","张三")); ht.insert(new Info("ct","李四")); ht.insert(new Info("wangwu","王五")); System.out.println(ht.find("a").getName()); System.out.println(ht.find("ct").getName()); } }