exerices

data/3.Java高阶/4.收集器/config.json

@@ -2,6 +2,5 @@
   "node_id": "java-0f1fc49b2e1c41368403ca2239810920",
   "keywords": [],
   "children": [],
-  "export": [],
-  "title": "收集器简介"
+  "export": ["to_list.json"]
 }
\ No newline at end of file

data/3.Java高阶/4.收集器/to_list.json

+{
+  "type": "code_options",
+  "author": "刘鑫",
+  "source": "to_list.md",
+  "notebook_enable": false
+}
\ No newline at end of file

data/3.Java高阶/4.收集器/to_list.md

+# Stream To List
+
+下面的选项尝试从一个整数 Stream 对象中构造 List。那么不正确的是：
+
+## 答案
+
+```java
+return  new ArrayList<>(stream);
+```
+
+## 选项
+
+### 推荐做法
+
+```java
+return stream.collect(Collectors.toList());
+```
+
+### 朴素做法，不推荐但可用
+
+```java
+List<Integer> result = new ArrayList<>();
+stream.foreach(x -> {
+    result.add(x);
+});
+return result;
+```
+
+### 方法引用
+
+```java
+List<Integer> result = new ArrayList<>();
+stream.foreach(result::add);
+```
+

data/3.Java高阶/4.收集器/to_set.json

+{
+  "type": "code_options",
+  "author": "刘鑫",
+  "source": "to_set.md",
+  "notebook_enable": false
+}
\ No newline at end of file

data/3.Java高阶/4.收集器/to_set.md

+# Stream To Set
+
+下面的选项尝试从一个整数 Stream 对象中构造 List。那么不正确的是：
+
+## 答案
+
+```java
+return  new HashSet<>(stream);
+```
+
+## 选项
+
+### 推荐做法
+
+```java
+return stream.collect(Collectors.toSet());
+```
+
+### 朴素做法，不推荐但可用
+
+```java
+List<Integer> result = new ArrayList<>();
+        stream.foreach(x -> {
+        result.add(x);
+        });
+        return result;
+```
+
+### 方法引用
+
+```java
+Set<Integer> result = new HashSet<>();
+stream.foreach(result::add);
+```
+
+
+
+
+