1. Add build script for Java.

2. Add height limitation for code blocks in extra.css.
3. Fix "节点" to "结点".

docs/chapter_hashing/hash_map.md

@@ -416,55 +416,9 @@ $$
 === "Java"
 
     ```java title="array_hash_map.java"
-    /* 键值对 int->String */
-    class Entry {
-        public int key;     // 键
-        public String val;  // 值
-        public Entry(int key, String val) {
-            this.key = key;
-            this.val = val;
-        }
-    }
-    
-    /* 基于数组简易实现的哈希表 */
-    class ArrayHashMap {
-        private List<Entry> bucket;
-        public ArrayHashMap() {
-            // 初始化一个长度为 100 的桶（数组）
-            bucket = new ArrayList<>();
-            for (int i = 0; i < 100; i++) {
-                bucket.add(null);
-            }
-        }
-    
-        /* 哈希函数 */
-        private int hashFunc(int key) {
-            int index = key % 100;
-            return index;
-        }
-    
-        /* 查询操作 */
-        public String get(int key) {
-            int index = hashFunc(key);
-            Entry pair = bucket.get(index);
-            if (pair == null) return null;
-            return pair.val;
-        }
-    
-        /* 添加操作 */
-        public void put(int key, String val) {
-            Entry pair = new Entry(key, val);
-            int index = hashFunc(key);
-            bucket.set(index, pair);
-        }
-    
-        /* 删除操作 */
-        public void remove(int key) {
-            int index = hashFunc(key);
-            // 置为 null，代表删除
-            bucket.set(index, null);
-        }
-    }
+    [class]{Entry}-[func]{}
+
+    [class]{ArrayHashMap}-[func]{}
     ```
 
 === "C++"