Java中HashMap原理及其使用场景，提供一个自定义HashMap实际案例

import java.util.LinkedList;

public class CustomHashMap<K, V> {
    private static final int DEFAULT_CAPACITY = 16;
    private LinkedList<Entry<K, V>>[] buckets;

    public CustomHashMap() {
        buckets = new LinkedList[DEFAULT_CAPACITY];
        for (int i = 0; i < DEFAULT_CAPACITY; i++) {
            buckets[i] = new LinkedList<>();
        }
    }

    private int getBucketIndex(K key) {
        return key.hashCode() % DEFAULT_CAPACITY;
    }

    public void put(K key, V value) {
        int index = getBucketIndex(key);
        LinkedList<Entry<K, V>> bucket = buckets[index];
        for (Entry<K, V> entry : bucket) {
            if (entry.getKey().equals(key)) {
                entry.setValue(value);
                return;
            }
        }
        bucket.add(new Entry<>(key, value));
    }

    public V get(K key) {
        int index = getBucketIndex(key);
        LinkedList<Entry<K, V>> bucket = buckets[index];
        for (Entry<K, V> entry : bucket) {
            if (entry.getKey().equals(key)) {
                return entry.getValue();
            }
        }
        return null;
    }

    private static class Entry<K, V> {
        private K key;
        private V value;

        public Entry(K key, V value) {
            this.key = key;
            this.value = value;
        }

        public K getKey() {
            return key;
        }

        public V getValue() {
            return value;
        }

        public void setValue(V value) {
            this.value = value;
        }
    }

    public static void main(String[] args) {
        CustomHashMap<String, Integer> map = new CustomHashMap<>();
        map.put("one", 1);
        map.put("two", 2);
        map.put("three", 3);

        System.out.println("Value for key 'one': " + map.get("one"));
        System.out.println("Value for key 'two': " + map.get("two"));
        System.out.println("Value for key 'three': " + map.get("three"));

        // Output:
        // Value for key 'one': 1
        // Value for key 'two': 2
        // Value for key 'three': 3
    }
}