scala集合类型，函数

- 日理万妓 2022-05-07 21:23 202阅读 0赞

1.  scala使用初步介绍
2.  函数： def …

# part1: scala 数组/集合基础 #

![在这里插入图片描述][70]

<table> 
 <thead> 
  <tr> 
   <th></th> 
   <th>Array</th> 
   <th>List，Set</th> 
   <th>Map</th> 
   <th>Tuple1…20</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>创建容器</td> 
   <td>Array(1,2,3)</td> 
   <td>List(1,2,3) / Array(1,2,3).toList</td> 
   <td>Map(“k1”-&gt;“1”,“k2”-&gt;“2”)</td> 
   <td>scala.Tuple3(1,2,3)/ (1,2,3)</td> 
  </tr> 
  <tr> 
   <td>取出元素</td> 
   <td>arr(0), arr(1)</td> 
   <td>list(0),list(1)</td> 
   <td>map(“k1”)</td> 
   <td>tup._1, tup._2</td> 
  </tr> 
  <tr> 
   <td>常用函数</td> 
   <td>size, sum,min, max,toList, flatMap</td> 
   <td>sortBy,reverse,toMap,flatMap,groupBy,reduce</td> 
   <td>map,mapValues,groupBy,filter</td> 
   <td></td> 
  </tr> 
 </tbody> 
</table>

# part2: 函数 #

函数

//for循环
    for(i<-1 to 9){
    	for(j <-1 to 9){
    		if(i>=j){
    			printf("%d * %d = %d \t", j,i,(j*i))
    		}
    	}
    	println()
    }
    
    import scala.util.control.Breaks._
    for(i<- 1 to 9; j<- 1 to 9){
    	if(i>=j){
    		printf("%d * %d = %d \t", j,i,(j*i))
    	}else {
    		if(j>i) {println() ; return}
    	}
    }
    for(i<-"hello"){
    	println(i)
    }

//while循环
    var x=5
    while( x>0){
    	println(x)
    	x-=1
    }

//定义方法
        def thread(f: () => Unit) = {
          new Thread() {
            override def run() = {
              f()
            }
          }.start()
        }
    
        //启动线程1 : 死循环打印a
        def f = {
          while (true)
            println("a")
          Thread.sleep(100)
        }
        thread(f _)
    
        //启动线程2：　打印一个hello
        thread(() => println("hello"))

//求解： 直线方程
    def f( x1:Int,y1:Int,  x2:Int, y2:Int ):Int=>Int = {
    
    	k=(y2-y1)/(x2-x1)
    	b=y1-k*x1
    
    	def fun(x:Int)={
    		k*x+b
    	}
    	fun _
    }
    f(1,2,3,4)(5)

[70]: /images/20220508/73b28b09baa6478ca052e788a4851072.png