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面试题面试题
先来看看常问的面试题有哪些
底层数据结构
hash冲突解决
1.7和1.8区别
扩容机制(为什么是2倍)
rehash过程
红黑树的左右旋
一、底层数据结构一、底层数据结构
// 1.位桶数组
transient Node[] table;//存储(位桶)的数组
// 2.数组元素Node实现了Entry接口
//Node是单向链表,它实现了Map.Entry接口
static class Node implements Map.Entry {
final int hash;
final K key;
V value;
Node next;
//构造函数Hash值 键 值 下一个节点
Node(int hash, K key, V value, Node next) {
this.hash = hash;
this.key = key;
this.value = value;
this.next = next;
}
public final K getKey() { return key; }
public final V getValue() { return value; }
public final String toString() { return key + = + value; }
public final int hashCode() {
return Objects.hashCode(key) ^ Objects.hashCode(value);
}
public final V setValue(V newValue) {
V oldValue = value;
value = newValue;
return oldValue;
}
//判断两个node是否相等,若key和value都相等,返回true。可以与自身比较为true
public final boolean equals(Object o) {
if (o == this)
return true;
if (o instanceof Map.Entry) {
Map.Entry e = (Map.Entry)o;
if (Objects.equals(key, e.getKey()) &&
Objects.equals(value, e.getValue()))
return true;
}
return false;
}
}
// 3.红黑树
static final class TreeNode extends LinkedHashMap.Entry {
TreeNode parent; // 父节点
TreeNode left; //左子树
TreeNode right;//右子树
TreeNode prev; // needed to unlink next upon deletion
boolean red; //颜色属性
TreeNode(int hash, K key, V val, Node next) {
super(hash, key, val, next);
}
//返回当前节点的根节点
final TreeNode root() {
for (TreeNode r = this, p;;) {
if ((p = r.parent) == null)
return r;
r = p;
}
}
}
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