采用java8的optional重写map中的getNode()方法

src/main/java/com/ximo/datastructuresinaction/leetcode/Solution804/Soluntion.java → src/main/java/com/ximo/datastructuresinaction/leetcode/Solution804/Solution.java

@@ -9,7 +9,7 @@
  * @author Ximo
  * @date 2018/11/14 22:54
  */
-public class Soluntion {
+public class Solution {
 
     private static final String[] CODES = new String[]{".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..",
             ".---", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--.."};

src/main/java/com/ximo/datastructuresinaction/map/LinkedListMap.java

@@ -0,0 +1,140 @@
+package com.ximo.datastructuresinaction.map;
+
+import java.util.Optional;
+
+/**
+ * @author Ximo
+ * @date 2018/11/14 23:32
+ */
+public class LinkedListMap<K, V> implements Map<K, V> {
+
+    /**
+     * 虚拟头节点
+     */
+    public Node dummyHead;
+    /**
+     * 大小
+     */
+    private int size;
+
+    public LinkedListMap() {
+        this.dummyHead = new Node();
+        size = 0;
+    }
+
+    /**
+     * 传入一个key 获得这个节点
+     *
+     * @param key key 健
+     * @return 这个健对应的节点信息
+     */
+    private Optional<Node> getNode(K key) {
+        Node cur = dummyHead.next;
+        while (cur != null) {
+            if (cur.key.equals(key)) {
+                return Optional.of(cur);
+            }
+            cur = cur.next;
+        }
+        return Optional.empty();
+    }
+
+    /**
+     * 添加 重复的元素 直接进行覆盖
+     *
+     * @param key   key
+     * @param value value
+     */
+    @Override
+    public void add(K key, V value) {
+        Optional<Node> nodeOpt = getNode(key);
+        if (nodeOpt.isPresent()) {
+            nodeOpt.get().value = value;
+        } else {
+            dummyHead.next = new Node(key, value, dummyHead.next);
+            size++;
+        }
+    }
+
+    /**
+     * 删除节点的信息
+     * 为空的时候 返回null
+     *
+     * @param key key
+     * @return 被删除的元素
+     */
+    @Override
+    public V remove(K key) {
+        Node prev = dummyHead;
+        while (prev.next != null) {
+            if (prev.next.key.equals(key)) {
+                break;
+            }
+            // 接着找
+            prev = prev.next;
+        }
+        if (prev.next != null) {
+            Node delNode = prev.next;
+            prev.next = delNode.next;
+            delNode.next = null;
+            size--;
+            return delNode.value;
+        }
+        return null;
+    }
+
+    @Override
+    public boolean contains(K key) {
+        return getNode(key).isPresent();
+    }
+
+    @Override
+    public V get(K key) {
+        return getNode(key).orElseGet(Node::new).value;
+    }
+
+    @Override
+    public void set(K key, V newValue) {
+        Optional<Node> nodeOpt = getNode(key);
+        if (!nodeOpt.isPresent()) {
+            throw new IllegalArgumentException("the key doesn't exist!");
+        }
+        nodeOpt.get().value = newValue;
+    }
+
+    @Override
+    public int getSize() {
+        return size;
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return getSize() == 0;
+    }
+
+    private class Node {
+        K key;
+
+        V value;
+
+        Node next;
+
+        Node(K key, V value, Node next) {
+            this.key = key;
+            this.value = value;
+            this.next = next;
+        }
+
+        Node(K key) {
+            this.key = key;
+        }
+
+        Node() {
+        }
+
+        @Override
+        public String toString() {
+            return key.toString() + ":" + value.toString();
+        }
+    }
+}

src/main/java/com/ximo/datastructuresinaction/map/Map.java

@@ -0,0 +1,23 @@
+package com.ximo.datastructuresinaction.map;
+
+/**
+ * @author Ximo
+ * @date 2018/11/14 23:28
+ */
+public interface Map<K, V> {
+
+    void add(K key, V value);
+
+    V remove(K key);
+
+    boolean contains(K key);
+
+    V get(K key);
+
+    void set(K key, V newValue);
+
+    int getSize();
+
+    boolean isEmpty();
+
+}