java hashmap 底层详细

此hashmap中使用到MyArrayList 阅读前 请先看 我写的 MyArrayList

package cn.com.test04;

class  MyIterator<E>{
    private MyArrayList<E> li;
    int i=0;
    MyIterator(MyArrayList<E> li){
        this.li=li;
    }
    public boolean hasNext(){
        
        if(i<li.size()&&li.get(i)!=null){
            return true;
        }else{
            return false;
        }
    }
    public E next(){
        return (E)li.get(i++);
    }
}
class MyHashMap<K,V>{
    private Node[] node;
    MyHashMap(){
        this(10);
    }
    MyHashMap(int length){
        node=new Node[length];
    }
    public void put(K k,V v){
        Node oldK = getNode(k);
        if(oldK!=null&&oldK.key.equals(k)){
            oldK.value=v;
        }else{
            int hashCode = getHashCode(k);
            Node oldNode = node[hashCode];
            Node newNode=new Node(k,v,oldNode,hashCode);
            node[hashCode]=newNode;
        }
        
        
    }
    public V get(K k){
        
        return (V)getNode(k).value;
    }
    public Node getNode(K k){
        int hashCode = getHashCode(k);
        Node oldNode = node[hashCode];
        Node temp=oldNode;
        while(temp!=null&&temp.key!=k){
            temp=temp.up;
        }
        return temp!=null?temp:null;
    }
    private int getHashCode(K k){
        return k.hashCode()%node.length;
    }
    public Object[] values(){
        return  getKeysAndValues("values").toArray();
    }
    public Object[] getKey(){
        return  getKeysAndValues("sada").toArray();
    }
    private MyArrayList getKeysAndValues(String aa){
        MyArrayList li= new MyArrayList();
        MyArrayList li1= new MyArrayList();
        for(int i=0;i<node.length;i++){
            Node mo = node[i];
                while(mo!=null){
                    li.add(mo.value);
                    li1.add(mo.key);
                    mo=mo.up;
                }
        }
        return aa=="values"?li:li1;
    }
    public MyIterator<K> KeyIterator(){
        return new MyIterator(getKeysAndValues("sada"));// MyIterator<String> =new new MyIterator(getKeysAndValues("sada"));
    }
    
    class Node<K,V>{
        K key;
        V value;
        Node up;
        int hashCode;
        Node(K key,V value,Node up,int hashCode){
            this.key=key;
            this.value=value;
            this.up=up;
            this.hashCode=hashCode;
        }
    }
}
public class t06 {

    public static void main(String[] args) {
        //1===1  '1'==49   "1"==49
        System.out.println((char)117);
         System.out.println("k".hashCode()%10);
         MyHashMap<String, String> h=new MyHashMap<String, String>();
        // 可以存大量的数据   分类管理   结合arraylist And linkedList 优点 
         // 可以存很多种数据  
         // 采用键值方式存取  适度快    
        // 遍历结果没得顺序   当有相同的键存如数据的时候  取得此键的值 永远是最后新存入的值
         h.put("a", "aaaaaaaaa");
         h.put("b", "bbbbbbbbb");
         h.put("k", "kkkkkkkkkkk");
         h.put("u", "uuuuuuuuu"); 
         h.put("a", "dfsdfdsgsd");
         h.put("f", "fffffffffff");
         h.put("h", "hhhhhhhhhhh");
         System.out.println(h.get("a")+"---------------");
         Object[] val = h.getKey();
         int i=0;
         for(Object o:val){
             System.out.println(h.get((String)o)+"==="+i++);
         }
         System.out.println("=======================");
         
         MyIterator<String> ke = h.KeyIterator();
         while(ke.hasNext()){
             System.out.println(ke.next()+"======00000");
         }
         
    }

}