AbstractHashMap

import java.util.ArrayList;
import java.util.Random;

public abstract class AbstractHashMap<K,V> extends AbstractMap<K,V>{
    protected int n=0;
    protected int capacity;
    private int prime;
    private long scale,shift;
    public AbstractHashMap(int cap,int p){
        prime=p;
        capacity=cap;
        Random rand=new Random();
        scale=rand.nextInt(prime-1)+1;
        shift=rand.nextInt(prime);
        createTable();
    }
    public AbstractHashMap(int cap){
        this(cap,109345121);
    }
    public AbstractHashMap(){
        this(17);
    }
    public int size(){
        return n;
    }
    public V get(K key){
        return bucketGet(hashValue(key),key);
    }
    public V remove(K key){
        return bucketRemove(hashValue(key),key);
    }
    public V put(K key,V value){
        V answer =bucketPut(hashValue(key),key,value);
        if(n>capacity/2)
            resize(2*capacity-1);
        return answer;
    }
    private int hashValue(K key){
        return (int)((Math.abs(key.hashCode()*scale+shift)%prime)%capacity);
    }
    private void resize(int newCap){
        ArrayList<Entry<K,V>>buffer=new ArrayList<>(n);
        for(Entry<K,V>e:entrySet())
            buffer.add(e);
        capacity=newCap;
        createTable();
        n=0;
        for(Entry<K,V>e:buffer)
            put(e.getKey(),e.getValue());

    }
    protected abstract void createTable();
    protected abstract V bucketGet(int h,K k);
    protected abstract V bucketPut(int h,K k,V v);
    protected abstract V bucketRemove(int h,K k);
}