LinkedListMap come true

07-Set-and-Map/03-Map-Basics/src/LinkedListMap.java

@@ -0,0 +1,116 @@
+/**
+ * @Auther: lss
+ * @Date: 2019/2/21 15:37
+ * @Description:
+ */
+public class LinkedListMap<K, V> implements Map<K, V> {
+
+ private class Node {
+ public K key;
+ public V value;
+ public Node next;
+
+ public Node(K key, V value, Node next) {
+ this.key = key;
+ this.value = value;
+ this.next = next;
+ }
+
+ public Node(K key) {
+ this(key, null, null);
+ }
+
+ public Node() {
+ this(null, null, null);
+ }
+
+ @Override
+ public String toString() {
+ return key.toString() + ":" + value.toString();
+ }
+ }
+
+ private Node dummyHead;
+ private int size;
+
+ public LinkedListMap() {
+ dummyHead = new Node();
+ size = 0;
+ }
+
+
+ @Override
+ public void add(K key, V value) {
+ // 确认当前映射有没有要添加的key
+ Node node = getNode(key);
+ if (node == null) {
+ dummyHead.next = new Node(key, value, dummyHead.next);
+ size++;
+ } else {
+ node.value = value;
+ }
+ }
+
+ @Override
+ public V remove(K key) {
+
+ Node prev = dummyHead;
+ while (prev.next != null) {
+ if (prev.next.key.equals(key))
+ break;
+ 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) != null;
+ }
+
+ @Override
+ public V get(K key) {
+ Node node = getNode(key);
+ return node == null ? null : node.value;
+ }
+
+ @Override
+ public void set(K key, V newValue) {
+
+ Node node = getNode(key);
+ if (node == null)
+ throw new IllegalArgumentException(key + "doesn't exits!");
+
+ node.value = newValue;
+ }
+
+ private Node getNode(K key) {
+
+ Node cur = dummyHead.next;
+ while (cur != null) {
+ if (cur.key.equals(key))
+ return cur;
+ cur = cur.next;
+ }
+ return null;
+ }
+
+ @Override
+ public int getSize() {
+ return size;
+ }
+
+ @Override
+ public boolean isEmpty() {
+ return size == 0;
+ }
+}