future

data/1.Java初阶/1.Java概述/1.什么是Java/config.json

-{
-  "node_id": "java-b45c34278b714bfbb6a6d80817e24639",
-  "keywords": [],
-  "children": [],
-  "export": [],
-  "title": "什么是Java"
-}
\ No newline at end of file

data/1.Java初阶/1.Java概述/2.JDK的下载/config.json

-{
-  "node_id": "java-238f8a0558a949f29e56dd830eae1b8b",
-  "keywords": [],
-  "children": [],
-  "export": [],
-  "title": "JDK的下载"
-}
\ No newline at end of file

data/1.Java初阶/1.Java概述/3.配置JDK/config.json

-{
-  "node_id": "java-007e13f0e4db49a1b181b1561104873c",
-  "keywords": [],
-  "children": [],
-  "export": [],
-  "title": "配置JDK"
-}
\ No newline at end of file

data/1.Java初阶/1.Java概述/4.Java的版本/config.json

-{
-  "node_id": "java-32823e681af949c4ae26e0bf9a9977a2",
-  "keywords": [],
-  "children": [],
-  "export": [],
-  "title": "Java的版本"
-}
\ No newline at end of file

data/1.Java初阶/1.Java概述/5.JavaAPI文档/config.json

-{
-  "node_id": "java-36e8a46b02764541acd2800e1b189403",
-  "keywords": [],
-  "children": [],
-  "export": [],
-  "title": "JavaAPI文档"
-}
\ No newline at end of file

data/1.Java初阶/1.Java概述/6.测试开发环境/config.json

-{
-  "node_id": "java-6d12bdbdeb7144aeb3649d50e0f06007",
-  "keywords": [],
-  "children": [],
-  "export": [],
-  "title": "测试开发环境"
-}
\ No newline at end of file

data/1.Java初阶/1.Java概述/config.json

-{
-  "node_id": "java-43e7bb3ee96c44e29df8e2f4063be49a",
-  "keywords": [],
-  "title": "Java概述"
-}
\ No newline at end of file

data/3.Java高阶/3.Java异步任务/1.线程与进程/config.json

@@ -2,5 +2,5 @@
   "node_id": "java-5dcc74ab2617434f91ae6aa1ba0ac661",
   "keywords": [],
   "children": [],
-  "export": []
+  "export": ["thread.json"]
 }
\ No newline at end of file

data/3.Java高阶/3.Java异步任务/1.线程与进程/counter.md

+# 计数器
+
+我们需要在工作线程中统计一个计数，这个计数是全局可见的，下面哪段代码有错？
+
+## 答案
+
+```java
+
+public class Worker extends Thread {
+    private static int count = 0;
+    public static int getCount() {
+        return count;
+    }
+    public static void increment() {
+        count = count + 1;
+    }
+    
+    @Override
+    public void run() {
+        //... do something
+        increment();
+    }
+}
+```
+
+## 选项
+
+### 内置并发对象
+
+```java
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class Worker extends Thread {
+    public static final AtomicInteger counter = new AtomicInteger(0);
+    
+    @Override
+    public void run() {
+        //... do something
+        counter.incrementAndGet();
+    }
+}
+```
+
+### 朴素的加锁方法
+
+```java
+
+public class Worker extends Thread {
+    private static volatile int count = 0;
+    public static int getCount() {
+        return count;
+    }
+    public static synchronized void increment() {
+        count = count + 1;
+    }
+
+    @Override
+    public void run() {
+        //... do something
+        increment();
+    }
+}
+```
+
+### 朴素的锁机制
+
+```java
+public class Worker extends Thread {
+    private static Lock lock = new ReentrantLock();
+    private static Integer count = 0;
+    public static int getCount() {
+        return count;
+    }
+    public static void increment() {
+        lock.lock();
+        try {
+            count = count + 1;
+        } finally {
+            lock.unlock();
+        }
+    }
+
+    @Override
+    public void run() {
+        //... do something
+        increment();
+    }
+}
+```

data/3.Java高阶/3.Java异步任务/1.线程与进程/thread.json

@@ -2,5 +2,6 @@
   "type": "code_options",
   "author": "刘鑫",
   "source": "thread.md",
-  "notebook_enable": false
+  "notebook_enable": false,
+  "exercise_id": "c1b604a5d2364a969361cd5fbb4ed3f8"
 }
\ No newline at end of file

data/3.Java高阶/3.Java异步任务/1.线程与进程/thread.md

+# 线程
+
+关于线程，哪一个选项的叙述是错的？
+
+## 答案
+
+线程比进程快。
+
+## 选项
+
+### A
+
+Java 的多线程代码可以并行在多个CPU上
+
+### B
+
+同一进程内的线程可以共享变量，而进程之间不共享变量。
+
+### C
+
+Java 的线程对象 Thread 调用 sleep 时，不阻塞其它线程
+
+### D
+
+通过实现 Thread 类型，可以自定义线程任务。
+
+### E
+
+可以在 Thread 的构造函数中传入一个 Runnable 对象来构造一个线程对象。
+
+### F
+
+Java 提供了了一些内置线程池类型，基于线程模型的异步任务可以使用这些资源。
\ No newline at end of file

data/3.Java高阶/3.Java异步任务/2.Future与CompletableFuture/future.json

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

data/3.Java高阶/3.Java异步任务/2.Future与CompletableFuture/future.md

+# Future 
+
+我们有如下代码：
+
+```java
+import java.util.concurrent.Executors;
+
+ExecutorService pool = Executors.newCachedThreadPool();
+
+var amount = 0.0f; 
+List<Future<Float>> futures = //submit jobs into the pool for create futures list
+
+for(var f: futures){
+    amount += f.get();
+}
+//...
+```
+
+下面分析中，错误的是
+
+## 答案
+
+此代码中有并发冲突
+
+## 选项
+
+### A
+
+如果future执行过程中有较多的阻塞或低速逻辑，有可能阻塞所有future。
+
+### B
+
+Future 对象的 get 方法有可能抛出异常。
+
+### C
+
+这段程序的执行时间取决于任务池的并行设置和最慢的future的执行时间。
+
+### D
+
+Future 可以不加修改运行在不同的 ExecutorService 实现上。
\ No newline at end of file

data/3.Java高阶/3.Java异步任务/2.“线框–管道”模型/config.json

-{
-  "node_id": "java-16a45f5c4e8242519004fe429dd335c9",
-  "keywords": [],
-  "children": [],
-  "export": [],
-  "title": "“线框–管道”模型"
-}
\ No newline at end of file

data/3.Java高阶/3.Java异步任务/4.“发布–订阅”以及反应式编程/config.json

-{
-  "node_id": "java-af9fa0cd03d643fdb6eecd75272140cf",
-  "keywords": [],
-  "children": [
-    {
-      "背压": {
-        "keywords": [],
-        "children": [],
-        "node_id": "java-bb8cf6772cb340c1adb74e9b231357a8",
-        "title": "背压"
-      }
-    },
-    {
-      "一种简单的真实背压": {
-        "keywords": [],
-        "children": [],
-        "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
-        "title": "一种简单的真实背压"
-      }
-    }
-  ],
-  "export": [],
-  "title": "“发布–订阅”以及反应式编程"
-}
\ No newline at end of file

data/3.Java高阶/3.Java异步任务/5.反应式系统和反应式编程/config.json

-{
-  "node_id": "java-d720f1f3560343559bcc30eca566d317",
-  "keywords": [],
-  "children": [],
-  "export": [],
-  "title": "反应式系统和反应式编程"
-}
\ No newline at end of file

data/3.Java高阶/4.反应式编程/1.反应式流以及Flow API/config.json

-{
-  "node_id": "java-96551e0eb6b044ff8f7fe9b5ff27fd73",
-  "keywords": [],
-  "children": [
-    {
-      "Flow类": {
-        "keywords": [],
-        "children": [],
-        "node_id": "java-35293e7729734213bcd67b97853eb50b",
-        "title": "Flow类"
-      }
-    },
-    {
-      "创建你的第一个反应式应用": {
-        "keywords": [],
-        "children": [],
-        "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
-        "title": "创建你的第一个反应式应用"
-      }
-    },
-    {
-      "使用Processor转换数据": {
-        "keywords": [],
-        "children": [],
-        "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
-        "title": "使用Processor转换数据"
-      }
-    }
-  ],
-  "export": [],
-  "title": "反应式流以及Flow API"
-}
\ No newline at end of file

data/3.Java高阶/4.反应式编程/2.使用反应式库RxJava/config.json

-{
-  "node_id": "java-bf773ed23aad4739866b582a3679e381",
-  "keywords": [],
-  "children": [
-    {
-      "转换及整合多个Observable": {
-        "keywords": [],
-        "children": [],
-        "node_id": "java-5a62f6f76fc04129aa628b3bd0f22609",
-        "title": "转换及整合多个Observable"
-      }
-    }
-  ],
-  "export": [],
-  "title": "使用反应式库RxJava"
-}
\ No newline at end of file

data/3.Java高阶/4.反应式编程/3.Java反射技术/config.json

-{
-  "node_id": "java-313674f323ec43919376c21a7e1bc88b",
-  "keywords": [],
-  "children": [
-    {
-      "通过反射构建对象": {
-        "keywords": [],
-        "children": [],
-        "node_id": "java-ac54833922254dceaccce5a2ffb0bf08",
-        "title": "通过反射构建对象"
-      }
-    },
-    {
-      "反射方法": {
-        "keywords": [],
-        "children": [],
-        "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
-        "title": "反射方法"
-      }
-    }
-  ],
-  "export": [],
-  "title": "Java反射技术"
-}
\ No newline at end of file

data/3.Java高阶/4.反应式编程/config.json

-{
-  "node_id": "java-0969aecf77a7416ba0fed596b2569a23",
-  "keywords": [],
-  "children": [
-    {
-      "对最佳价格查询器应用的优化": {
-        "keywords": [],
-        "children": [],
-        "node_id": "java-39915bb35ba34d41a11b6715aa7c687b",
-        "title": "对最佳价格查询器应用的优化"
-      }
-    }
-  ],
-  "export": [],
-  "title": "反应式编程"
-}
\ No newline at end of file

data/3.Java高阶/5.Apache Common/config.json

-{
-  "node_id": "java-e5d307b8ce2049648b4afd9fecdb48b0",
-  "keywords": []
-}
\ No newline at end of file

data/tree.json

@@ -8,56 +8,6 @@
           "node_id": "java-71a99d2763734420aee110c5c5b904d8",
           "keywords": [],
           "children": [
-            {
-              "Java概述": {
-                "node_id": "java-43e7bb3ee96c44e29df8e2f4063be49a",
-                "keywords": [],
-                "children": [
-                  {
-                    "什么是Java": {
-                      "node_id": "java-b45c34278b714bfbb6a6d80817e24639",
-                      "keywords": [],
-                      "children": []
-                    }
-                  },
-                  {
-                    "JDK的下载": {
-                      "node_id": "java-238f8a0558a949f29e56dd830eae1b8b",
-                      "keywords": [],
-                      "children": []
-                    }
-                  },
-                  {
-                    "配置JDK": {
-                      "node_id": "java-007e13f0e4db49a1b181b1561104873c",
-                      "keywords": [],
-                      "children": []
-                    }
-                  },
-                  {
-                    "Java的版本": {
-                      "node_id": "java-32823e681af949c4ae26e0bf9a9977a2",
-                      "keywords": [],
-                      "children": []
-                    }
-                  },
-                  {
-                    "JavaAPI文档": {
-                      "node_id": "java-36e8a46b02764541acd2800e1b189403",
-                      "keywords": [],
-                      "children": []
-                    }
-                  },
-                  {
-                    "测试开发环境": {
-                      "node_id": "java-6d12bdbdeb7144aeb3649d50e0f06007",
-                      "keywords": [],
-                      "children": []
-                    }
-                  }
-                ]
-              }
-            },
             {
               "第一个Java程序": {
                 "node_id": "java-379b792dde024090a7ed43b392ece2c5",
@@ -4038,139 +3988,14 @@
                     }
                   },
                   {
-                    "“线框–管道”模型": {
-                      "node_id": "java-16a45f5c4e8242519004fe429dd335c9",
-                      "keywords": [],
-                      "children": []
-                    }
-                  },
-                  {
-                    "为并发而生的CompletableFuture和结合器": {
+                    "CompletableFuture": {
                       "node_id": "java-90f4b7c696464886af9c8de8cbd95338",
                       "keywords": [],
                       "children": []
                     }
-                  },
-                  {
-                    "“发布–订阅”以及反应式编程": {
-                      "node_id": "java-af9fa0cd03d643fdb6eecd75272140cf",
-                      "keywords": [],
-                      "children": [
-                        {
-                          "背压": {
-                            "keywords": [],
-                            "children": [],
-                            "node_id": "java-bb8cf6772cb340c1adb74e9b231357a8",
-                            "title": "背压"
-                          }
-                        },
-                        {
-                          "一种简单的真实背压": {
-                            "keywords": [],
-                            "children": [],
-                            "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
-                            "title": "一种简单的真实背压"
-                          }
-                        }
-                      ]
-                    }
-                  },
-                  {
-                    "反应式系统和反应式编程": {
-                      "node_id": "java-d720f1f3560343559bcc30eca566d317",
-                      "keywords": [],
-                      "children": []
-                    }
                   }
                 ]
               }
-            },
-            {
-              "反应式编程": {
-                "node_id": "java-0969aecf77a7416ba0fed596b2569a23",
-                "keywords": [],
-                "children": [
-                  {
-                    "反应式流以及Flow API": {
-                      "node_id": "java-96551e0eb6b044ff8f7fe9b5ff27fd73",
-                      "keywords": [],
-                      "children": [
-                        {
-                          "Flow类": {
-                            "keywords": [],
-                            "children": [],
-                            "node_id": "java-35293e7729734213bcd67b97853eb50b",
-                            "title": "Flow类"
-                          }
-                        },
-                        {
-                          "创建你的第一个反应式应用": {
-                            "keywords": [],
-                            "children": [],
-                            "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
-                            "title": "创建你的第一个反应式应用"
-                          }
-                        },
-                        {
-                          "使用Processor转换数据": {
-                            "keywords": [],
-                            "children": [],
-                            "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
-                            "title": "使用Processor转换数据"
-                          }
-                        }
-                      ]
-                    }
-                  },
-                  {
-                    "使用反应式库RxJava": {
-                      "node_id": "java-bf773ed23aad4739866b582a3679e381",
-                      "keywords": [],
-                      "children": [
-                        {
-                          "转换及整合多个Observable": {
-                            "keywords": [],
-                            "children": [],
-                            "node_id": "java-5a62f6f76fc04129aa628b3bd0f22609",
-                            "title": "转换及整合多个Observable"
-                          }
-                        }
-                      ]
-                    }
-                  },
-                  {
-                    "Java反射技术": {
-                      "node_id": "java-313674f323ec43919376c21a7e1bc88b",
-                      "keywords": [],
-                      "children": [
-                        {
-                          "通过反射构建对象": {
-                            "keywords": [],
-                            "children": [],
-                            "node_id": "java-ac54833922254dceaccce5a2ffb0bf08",
-                            "title": "通过反射构建对象"
-                          }
-                        },
-                        {
-                          "反射方法": {
-                            "keywords": [],
-                            "children": [],
-                            "node_id": "569d5e11c4fc5de7844053d9a733c5e8",
-                            "title": "反射方法"
-                          }
-                        }
-                      ]
-                    }
-                  }
-                ]
-              }
-            },
-            {
-              "Apache Common": {
-                "node_id": "java-e5d307b8ce2049648b4afd9fecdb48b0",
-                "keywords": [],
-                "children": []
-              }
             }
           ]
         }