Scala is set (Set)

Set

Set (set) is not representative of repeating elements of the collection. Set has the following properties:

1. Element does not repeat
2. It does not guarantee insertion order

The scala also divided into two sets, one is immutable set, the other variable is set.

Set immutable

definition

grammar

//创建一个空的不可变集，语法格式
val/var 变量名 = Set[类型]()
//给定元素来创建一个不可变集，语法格式
val/var 变量名 = Set(元素1, 元素2, 元素3...)

The sample code

//定义一个空的不可变集
val a = Set[Int]()
//定义一个不可变集，保存以下元素：1,1,3,2,4,8
 val a = Set(1,1,3,2,4,8)

Basic Operations

• Gets the size set size( )
• Traversing the set 和遍历数组一致( )
• Adding an element to generate a the Set ( +)
• Splicing two sets, generates a the Set ( ++)
• And stitching set list, generate a the Set ( ++)

The sample code

//1. 创建一个集，包含以下元素：1,1,2,3,4,5
val a = Set(1, 1, 2, 3, 4, 5)
//2. 获取集的大小
a.size
//3. 遍历集，打印每个元素 (set集是乱序的)
for (i <- a) println(i)
//4. 删除元素1，生成新的集
a - 1
//5. 拼接另一个集（6, 7, 8)
a ++ Set(6, 7, 8)
//6. 拼接一个列表(6,7,8, 9)
a ++ List(6, 7, 8, 9)

Variable Set

definition

Create a consistent set of variable can not change the way set, but need to import a variable set in advance class.
import scala.collection.mutable.Set

The sample code

import scala.collection.mutable.Set
//1. 定义一个可变集，包含以下元素: 1,2,3, 4  (mutable)可以省略
val a = mutable.Set(1,2,3,4)
//2. 添加元素5到可变集中
a += 5
//3. 从可变集中移除元素1
a -= 1