【java基础】java集合之HashTable,HashSet,HashMap
【一】HashSet
(1)HashSet内部维护的是一个HashMap,具体原理见java集合之HashMap
【二】HashTable
(1)HashTable内部维护的是一个Entry的数组。Entry又是一个单项链表的结构。
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private static class Entry<K,V> implements Map.Entry<K,V> { final int hash; final K key; V value; Entry<K,V> next; protected Entry(int hash, K key, V value, Entry<K,V> next) { this.hash = hash; this.key = key; this.value = value; this.next = next; } @SuppressWarnings("unchecked") protected Object clone() { return new Entry<>(hash, key, value, (next==null ? null : (Entry<K,V>) next.clone())); } // Map.Entry Ops public K getKey() { return key; } public V getValue() { return value; } public V setValue(V value) { if (value == null) throw new NullPointerException(); V oldValue = this.value; this.value = value; return oldValue; } public boolean equals(Object o) { if (!(o instanceof Map.Entry)) return false; Map.Entry<?,?> e = (Map.Entry<?,?>)o; return (key==null ? e.getKey()==null : key.equals(e.getKey())) && (value==null ? e.getValue()==null : value.equals(e.getValue())); } public int hashCode() { return hash ^ Objects.hashCode(value); } public String toString() { return key.toString()+"="+value.toString(); } }
(2)