From 22892f7f50437c48c160c4ff13f7d3e091af2a92 Mon Sep 17 00:00:00 2001
From: kennethcheng <a1478925630@163.com>
Date: Sun, 13 Sep 2026 19:24:24 +0800
Subject: [PATCH] =?UTF-8?q?feat:ChatGPT=E7=AC=AC=205=20=E8=AF=BE=EF=BC=9A?=
 =?UTF-8?q?=E5=87=BD=E6=95=B0=E4=BD=9C=E4=B8=BA=E5=8F=82=E6=95=B0?=
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---
 src/main/scala/practise5/demo/Demo.scala      | 21 +++++++++++
 .../practise5/exercises/Exercises1.scala      | 29 +++++++++++++++
 .../practise5/exercises/Exercises2.scala      | 34 ++++++++++++++++++
 .../practise5/exercises/Exercises3.scala      | 29 +++++++++++++++
 .../practise5/exercises/Exercises4.scala      | 35 ++++++++++++++++++
 .../practise5/exercises/Exercises5.scala      | 36 +++++++++++++++++++
 6 files changed, 184 insertions(+)
 create mode 100644 src/main/scala/practise5/demo/Demo.scala
 create mode 100644 src/main/scala/practise5/exercises/Exercises1.scala
 create mode 100644 src/main/scala/practise5/exercises/Exercises2.scala
 create mode 100644 src/main/scala/practise5/exercises/Exercises3.scala
 create mode 100644 src/main/scala/practise5/exercises/Exercises4.scala
 create mode 100644 src/main/scala/practise5/exercises/Exercises5.scala

diff --git a/src/main/scala/practise5/demo/Demo.scala b/src/main/scala/practise5/demo/Demo.scala
new file mode 100644
index 0000000..a296076
--- /dev/null
+++ b/src/main/scala/practise5/demo/Demo.scala
@@ -0,0 +1,21 @@
+package practise5.demo
+/*
+doSomething
+↓
+需要一个函数
+↓
+x => x * 2
+↓
+把这个函数交给 doSomething
+
+这就是：
+函数作为参数传递。
+*/
+object Demo {
+  def main(args: Array[String]): Unit = {
+    doSomething(x => x * 2)
+  }
+  private def doSomething(f: Int => Int): Unit = {
+    println(f(10))
+  }
+}
diff --git a/src/main/scala/practise5/exercises/Exercises1.scala b/src/main/scala/practise5/exercises/Exercises1.scala
new file mode 100644
index 0000000..3b2fe2b
--- /dev/null
+++ b/src/main/scala/practise5/exercises/Exercises1.scala
@@ -0,0 +1,29 @@
+package practise5.exercises
+
+/*
+练习 1
+
+定义：
+def operate(a: Int, b: Int, f: (Int, Int) => Int): Int = {
+  // ...
+}
+
+要求让它能够这样使用：
+println(operate(10, 20, (a, b) => a + b))
+
+输出：
+30
+
+提示：
+函数参数 f 可以这样调用：
+
+f(a, b)*/
+object Exercises1 {
+  def main(args: Array[String]): Unit = {
+    println(operate(10, 20, (a, b) => a + b))
+  }
+
+  def operate(a: Int, b: Int, f: (Int, Int) => Int): Int = {
+    f(a, b)
+  }
+}
diff --git a/src/main/scala/practise5/exercises/Exercises2.scala b/src/main/scala/practise5/exercises/Exercises2.scala
new file mode 100644
index 0000000..a1a7459
--- /dev/null
+++ b/src/main/scala/practise5/exercises/Exercises2.scala
@@ -0,0 +1,34 @@
+package practise5.exercises
+
+/*
+让下面这些都能正常工作：
+println(operate(10, 20, (a, b) => a + b))
+println(operate(10, 20, (a, b) => a - b))
+println(operate(10, 20, (a, b) => a * b))
+
+输出：
+30
+-10
+200
+
+注意：
+operate 自己并不知道你要做加法、减法还是乘法。
+
+它只负责：
+接收两个数字
++
+  接收一个函数
++
+  执行这个函数
+*/
+object Exercises2 {
+  def main(args: Array[String]): Unit = {
+    println(operate(10, 20, (a, b) => a + b))
+    println(operate(10, 20, (a, b) => a - b))
+    println(operate(10, 20, (a, b) => a * b))
+  }
+
+  def operate(a: Int, b: Int, f1: (Int, Int) => Int): Int = {
+    f1(a, b)
+  }
+}
diff --git a/src/main/scala/practise5/exercises/Exercises3.scala b/src/main/scala/practise5/exercises/Exercises3.scala
new file mode 100644
index 0000000..d9399f4
--- /dev/null
+++ b/src/main/scala/practise5/exercises/Exercises3.scala
@@ -0,0 +1,29 @@
+package practise5.exercises
+
+/*
+练习 3
+
+自己定义：
+def calculate(a: Int, f: Int => Int): Int
+
+要求：
+println(calculate(10, x => x * 2))
+
+输出：
+20
+
+以及：
+println(calculate(10, x => x * 3))
+
+输出：
+30
+*/
+object Exercises3 {
+  def main(args: Array[String]): Unit = {
+    println(calculate(10, x => x * 2))
+    println(calculate(10, x => x * 3))
+  }
+  private def calculate(a: Int, f: Int => Int): Int = {
+    f(a)
+  }
+}
diff --git a/src/main/scala/practise5/exercises/Exercises4.scala b/src/main/scala/practise5/exercises/Exercises4.scala
new file mode 100644
index 0000000..2093df8
--- /dev/null
+++ b/src/main/scala/practise5/exercises/Exercises4.scala
@@ -0,0 +1,35 @@
+package practise5.exercises
+
+/*
+练习 4
+
+给：
+val nums = List(1, 2, 3, 4, 5)
+
+先自己定义一个函数：
+val double = (x: Int) => x * 2
+
+然后不要直接写：
+nums.map(x => x * 2)
+
+而是：
+nums.map(double)
+
+观察结果。
+
+也就是说：
+x => x * 2
+
+和：
+double
+
+都可以作为 map 的参数。
+*/
+object Exercises4 {
+  def main(args: Array[String]): Unit = {
+    val nums = List(1, 2, 3, 4, 5)
+    val double = (x: Int) => x * 2
+    println(nums.map(double))
+    println(nums.map(x => x * 2))
+  }
+}
diff --git a/src/main/scala/practise5/exercises/Exercises5.scala b/src/main/scala/practise5/exercises/Exercises5.scala
new file mode 100644
index 0000000..2283137
--- /dev/null
+++ b/src/main/scala/practise5/exercises/Exercises5.scala
@@ -0,0 +1,36 @@
+package practise5.exercises
+
+/*
+练习 5 ⭐⭐⭐
+
+最后做一道非常接近真实 Scala/Spark 的：
+val nums = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
+
+完成：
+1. 过滤出偶数
+  2. 每个偶数乘 10
+3. 最终得到 List(20, 40, 60, 80, 100)
+
+要求使用：
+filter
+map
+
+并且尽量使用函数值变量，例如：
+val isEven = ...
+val multiply10 = ...
+
+最终类似：
+nums
+  .filter(isEven)
+  .map(multiply10)
+*/
+
+object Exercises5 {
+  def main(args: Array[String]): Unit = {
+    val nums = List(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
+    val isEven = (x:Int) => x%2==0
+    val multiply10 = (x:Int) => x * 10
+    val result = nums.filter(isEven).map(multiply10)
+    println(result)
+  }
+}