手写hashmap

好的，这里是一个简单的手写hashmap的实现：

public class MyHashMap<K, V> {
    private int size;
    private int capacity;
    private Node<K, V>[] table;

    private static class Node<K, V> {
        final K key;
        V value;
        Node<K, V> next;

        Node(K key, V value, Node<K, V> next) {
            this.key = key;
            this.value = value;
            this.next = next;
        }
    }

    public MyHashMap(int capacity) {
        this.size = 0;
        this.capacity = capacity;
        this.table = new Node[capacity];
    }

    public V get(K key) {
        int index = hash(key);
        Node<K, V> node = table[index];
        while (node != null) {
            if (node.key.equals(key)) {
                return node.value;
            }
            node = node.next;
        }
        return null;
    }

    public void put(K key, V value) {
        int index = hash(key);
        Node<K, V> node = table[index];
        while (node != null) {
            if (node.key.equals(key)) {
                node.value = value;
                return;
            }
            node = node.next;
        }

        // If the key does not exist in the map, add a new node to the front of the list at the index.
        Node<K, V> newNode = new Node<>(key, value, table[index]);
        table[index] = newNode;
        size++;

        // If the map has exceeded its load factor, resize the table.
        if (size > capacity * 0.75) {
            resize();
        }
    }

    public void remove(K key) {
        int index = hash(key);
        Node<K, V> node = table[index];
        Node<K, V> prev = null;
        while (node != null) {
            if (node.key.equals(key)) {
                if (prev == null) {
                    table[index] = node.next;
                } else {
                    prev.next = node.next;
                }
                size--;
                return;
            }
            prev = node;
            node = node.next;
        }
    }

    private int hash(K key) {
        return key.hashCode() % capacity;
    }

    private void resize() {
        capacity *= 2;
        Node<K, V>[] newTable = new Node[capacity];
        for (Node<K, V> node : table) {
            while (node != null) {
                Node<K, V> next = node.next;
                int index = hash(node.key);
                node.next = newTable[index];
                newTable[index] = node;
                node = next;
            }
        }
        table = newTable;
    }
}

这个HashMap使用链表来解决冲突，并且在size超过capacity*0.75时会自动扩容。