auto commit

Author: CyC2018

notes/缓存.md

@@ -88,14 +88,12 @@ public class LRU<K, V> implements Iterable<K> {
 
     public void put(K key, V value) {
 
-        Node node;
         if (map.containsKey(key)) {
-            node = map.get(key);
+            Node node = map.get(key);
             unlink(node);
         }
-        if (node == null) {
-            node = new Node(key, value);
-        }
+
+        Node node = new Node(key, value);
         map.put(key, node);
         appendHead(node);
 
@@ -107,28 +105,38 @@ public class LRU<K, V> implements Iterable<K> {
 
 
     private void unlink(Node node) {
+
         Node pre = node.pre;
         Node next = node.next;
+
         pre.next = next;
         next.pre = pre;
-        
+
         node.pre = null;
         node.next = null;
     }
 
 
     private void appendHead(Node node) {
-        node.next = head.next;
-        node.next.pre = node;
+        Node next = head.next;
+        node.next = next;
+        next.pre = node;
         node.pre = head;
         head.next = node;
     }
 
 
     private Node removeTail() {
+
         Node node = tail.pre;
-        tail.pre = node.pre;
-        node.pre.next = tail;
+
+        Node pre = node.pre;
+        tail.pre = pre;
+        pre.next = tail;
+
+        node.pre = null;
+        node.next = null;
+
         return node;
     }
 
@@ -138,6 +146,7 @@ public class LRU<K, V> implements Iterable<K> {
 
         return new Iterator<K>() {
             private Node cur = head.next;
+
             @Override
             public boolean hasNext() {
                 return cur != tail;