分离链接法 ，h存放数据

package com.algorithm.charactor1;

import java.util.LinkedList;

/**
 *本质是一个数组， 通过hash算法，指定到具体的数组下标 ,该下表下是一个链表，
    分离链接。每个数组位置是一个链表。
 */
public class Hash {
	
	//数组
	private LinkedList<Student> [] array;
	//多少个元素
	private int currentSize;
	
	private static int DEFAULTSIZE = 17;
	
	
	//插入操作
	public void  insert(Student student){
		Integer index = myHash(student);
		LinkedList<Student> linkedList = array[index];
		if (!linkedList.contains(student)) {
			linkedList.add(student);
			this.currentSize++;
		}
		if (currentSize+1 > array.length) {
			//扩容操作
			rehash();
		}
		
	}
	
	private void rehash() {
		LinkedList<Student> []newArray = new LinkedList[nextPrime(array.length)];
		int i =0 ;
		for (LinkedList<Student> linkedList : newArray) {//初始化新的链表数组
			newArray[i++] = new LinkedList<Hash.Student>();
		}
		array = newArray; 
		currentSize = 0;
		for (LinkedList<Student> linkedList : array) {//老的链表数组
			for (Student student : linkedList) {
				insert(student);//把老数组中的值，重新计算hash放到新的 数组中。
			}
		}
		
	}

	public void remove(Student student){
		Integer index = myHash(student);
		LinkedList<Student> linkedList = array[index];
		if (!linkedList.contains(student)) {
			return ;
		}
		linkedList.remove(student);
		this.currentSize--;
	}
	
	public Boolean contains(Student student){
		Integer index = myHash(student);
		LinkedList<Student> linkedList = array[index];
		return linkedList.contains(student);
	}
	
	
	
	public Hash() {
		this(DEFAULTSIZE);
	}
	
	public Hash(int size) {
		Integer nextPrime = nextPrime(size);
		array = new LinkedList[nextPrime];
		int index =0 ;
		for (LinkedList<Student> linkedList : array) {
			array[index++] = new LinkedList<Hash.Student>();
		}
	}

	public Integer myHash(Student student){
		int hashCode = student.hashCode();
	    int index = hashCode % array.length;
	    index =  index < 0 ? index + array.length : index;
		return index;
	}


	class Student{
	  String name;
	  int age;
	  @Override
		public int hashCode() {
		  return name.hashCode();
		}
	  
	  @Override
		public boolean equals(Object obj) {
		  return obj instanceof Student && ((Student)obj).name.equals(this.name);
		}

	public Student(String name) {
		super();
		this.name = name;
	}
	  
	  
	}
	
	//素数计算，网上抄的
	public static Integer nextPrime(Integer begin){
		int i;
		int j;
		for(i =begin;;i++){
			boolean flag = true;
			for(j=2;j<=i/2;j++){
				if(i%j==0){
					flag = false;
					break;
				}else if(i%j!=0){
					continue;
				}else{
					break;
				}
			}
			if(flag) {
				return i;
			}
		}
	}
	
	public static void main(String[] args) {
		Hash hash = new Hash(101);
		hash.insert(hash.new Student("ll"));
		for (LinkedList<Student> linkedList : hash.array) {
			System.out.println(linkedList);
		}
	}
}