HashMap源码手写简易篇（数组+链表）

public interface Map<K,V> {
    V put(K k,V v);
    V get(K k);
    int size();
    interface Entry<K,V>{
        K getKey();
        V getValue();
    }
}

public class HashMap<K,V> implements Map<K,V> {
    Entry<K,V>[] table=null;
    int size=0;
    public HashMap() {
       table = new Entry[16];
    }
    @Override
    public V put(K k, V v) {
        int index=hash(k);
        Entry<K, V> entry = table[index];
        if(entry==null){
            table[index]=new Entry<>(k,v,index,null);
            size++;
        }
        else {
            table[index]=new Entry<>(k,v,index,entry);
            size++;
        }
        return table[index].getValue();
    }
    private int hash(K k){
        int index=k.hashCode()%16;
        return index>=0?index:Math.abs(index);
    }
    @Override
    public V get(K k) {
        int index=hash(k);
        Entry<K, V> entry = findValue(table[index], k);
        return entry==null?null:entry.getValue();
    }
    public Entry<K,V> findValue(Entry<K,V> entry,K k){
        if(k.equals(entry.getKey())||k==entry.getKey()){
            return entry;
        }else {
           if(entry.next!=null){
               return findValue(entry.next,k);
           }
           return null;
        }
    }
    @Override
    public int size() {
        return size;
    }
    class Entry<K,V> implements Map.Entry<K,V>{
        K k;
        V v;
        int index;
        Entry<K,V> next;
        public Entry(K k, V v, int index, Entry<K, V> next) {
            this.k = k;
            this.v = v;
            this.index = index;
            this.next = next;
        }
        @Override
        public K getKey() {
            return k;
        }
        @Override
        public V getValue() {
            return v;
        }
    }
}