Scala函数代码整理：匿名函数、柯理化、模式匹配等

object Demon1 { def main(args: Array[String]): Unit = { //函数1 def function1(x: Int, y: Int): Int = x + y println("函数1：" + function1(1, 2)) println("=====================================") //函数2(匿名函数) val function2 = (x: Int, y: Int) => (x + y) println("匿名函数2：" + function2(1, 2)) println("=====================================") //函数3 val function3: (Int, Int) => Int = (_ + _) println("函数3：" + function3(1, 2)) println("=====================================") //函数作为参数1 def square(x: Int, y: Int) = x * y def function4(f: (Int, Int) => Int, name: String) = { //给作为参数的函数赋值 val res = f(2, 3) //返回结果 name + ":" + res } println("函数为参数的1：" + function4(square, "sam")) //函数作为参数2,在定义的函数参数列表中定义一个临时的函数 def func(f: (Int, Int) => Int, name: String) = { //给作为参数的函数赋值 val res = f(2, 3) //返回结果 name + ":" + res } val res = func((x: Int, y: Int) => x + y, "sam") println("函数为参数的2：" + res) println("=====================================") //无返回值函数1 def function5(name: String) = { name println("无返回值函数1.1") //因为只返回最后一个表达式的结果 } println(function5("sam")) def function6(name: String) = { println("无返回值函数1.2") name } println(function6("sam")) println("=====================================") //无返回值函数2 val function7 = (name: String) => { name println("无返回值函数2") } println(function7("sally")) println("=====================================") //函数作为返回值类型1 def function8(): (Int, Int) => Int = { def demon(x: Int, y: Int) = { x + y } //返回demon demon } println("函数作为返回值类型1: " + function8()(1, 2)) println("=====================================") //函数作为返回值类型2 def function9(n: Int): (Int, Int) => Int = { if (n % 2 == 0) { def funAdd(x: Int, y: Int) = x + y funAdd } else { def funDelet(x: Int, y: Int) = x - y funDelet } } println("函数作为返回值类型2: " + function9(4)(5, 3)) println("=====================================") //函数作为返回值，函数作为参数列表 def leng(s: String) = { s.length } //输入一个姓名，返回姓名的长度，长度定义为一个函数，返回值类型的函数：输入今天是星期几，输出一段话 def function10(f: (String) => Int, name: String): (Int) => Unit = { val l = f(name) if (l % 2 == 0) { def d1(x: Int) = { println("今天是你的幸运日") } d1 } else { (x: Int) => { println("今天就不要出门了") } } } function10(leng, "saml")(6) println("=====================================") //柯理化 def currying(a: Int, b: Int)(c: Int, d: Int) = { a + b + c + d } println("柯理化函数：" + currying(1, 2)(3, 4)) println("=====================================") //模式匹配1 def demon1(x: Int): String = x match { case 1 => "one" case 2 => "two" case _ => "other" } println("模式匹配1：" + demon1(1)) println("=====================================") //模式匹配2 def demon2(x: Any): String = x match { case x: Int => "Int类型" case x: String => "String类型" case _ => "其他类型" } println("模式匹配2：" + demon2("sdas")) println("=====================================") //样例类 case class Student(name: String, age: Int) def ex(student: Student) = student match { case Student("sam", 19) => println("My name is " + student.name + ",I'm " + student.age + " years old") case Student(name, age) => println("My name is " + student.name + ",I'm " + student.age + " years old") } val stu = Student("Dally", 19) ex(stu) println("=====================================") //隐式函数1(类型匹配，按类型匹配，即在一个类中只能有一个类型的隐式) implicit var a: Int = 10 def demon3(a: Int, b: Int)(implicit c: Int) = { a + b + c } println(demon3(1, 2)) println("=====================================") //隐式函数2 def demon4(a: Int, b: Int)(implicit c: Int) = { a + b + c } println(demon4(1, 2)(5)) println("=====================================") //隐式函数3 def demon5(a: Int, b: Int)(implicit c: Int,d:Int) = { a + b + c+d } println(demon5(1,2)(3,4)) //隐式函数4 //implicit var s:String="John" def demon6(a:Int)(implicit b:Int,c:String)={ a+b+c } println(demon6(1)(2,"John")) println("=====================================") //隐式方法 implicit def DoubleToInt(a:Double)={a.toInt} val x:Int=3.5 //x的值自动转为整型 println(x) } }