【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。

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();
}
}

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