1. 给集添加元素
1) 用 +=,++= 和 add 给可变集添加元素.
- scala> var set = scala.collection.mutable.Set[Int]()
- set: scala.collection.mutable.Set[Int] = Set()
- scala> set += 1
- res48: scala.collection.mutable.Set[Int] = Set(1)
- scala> set += (2,3)
- res49: scala.collection.mutable.Set[Int] = Set(1, 2, 3)
- scala> set ++= Vector(4,5)
- res50: scala.collection.mutable.Set[Int] = Set(1, 5, 2, 3, 4)
- scala> set.add(6)
- res51: Boolean = true
- scala> set
- res52: scala.collection.mutable.Set[Int] = Set(1, 5, 2, 6, 3, 4)
- scala> set.add(5)
- res53: Boolean = false
2) 使用 + 和 ++ 方法, 通过向前一个集添加元素生成一个新的集.
- scala> val set = Set(1,3,5,2,7)
- set: scala.collection.immutable.Set[Int] = Set(5, 1, 2, 7, 3)
- scala> val set1 = set + (8,9)
- set1: scala.collection.immutable.Set[Int] = Set(5, 1, 9, 2, 7, 3, 8)
- scala> val set2 = set1 ++ List(10,11)
- set2: scala.collection.immutable.Set[Int] = Set(5, 10, 1, 9, 2, 7, 3, 11, 8)
2. 从集中删除元素
1) 处理可变集时, 用 -= 和 --= 从集中删除元素.
- scala> var set = scala.collection.mutable.Set(1,2,3,4,5)
- set: scala.collection.mutable.Set[Int] = Set(1, 5, 2, 3, 4)
- scala> set -= 1
- res57: scala.collection.mutable.Set[Int] = Set(5, 2, 3, 4)
- scala> set -= (2,3)
- res58: scala.collection.mutable.Set[Int] = Set(5, 4)
- scala> set --= Array(4,5)
- res59: scala.collection.mutable.Set[Int] = Set()
2) 处理可变集, retain 和 clear 删除集中元素.
- scala> var set = scala.collection.mutable.Set(1,2,3,4,5)
- set: scala.collection.mutable.Set[Int] = Set(1, 5, 2, 3, 4)
- scala> set.retain(_> 2);println(set)
- Set(5, 3, 4)
- scala> set.clear;println(set)
- Set()
3) 处理可变集时, remove 的返回值可以提示集是否有元素被删除.
- scala> var set = scala.collection.mutable.Set(1,2,3,4,5)
- set: scala.collection.mutable.Set[Int] = Set(1, 5, 2, 3, 4)
- scala> set.remove(2);println(set)
- Set(1, 5, 3, 4)
- scala> set.remove(3)
- res64: Boolean = true
- scala> set
- res65: scala.collection.mutable.Set[Int] = Set(1, 5, 4)
4) 处理不可变集时, 可以使用 - 和 -- 操作符删除元素, 同时将结果重新赋给一个新的变量.
- scala> val s1 = Set(1,2,3,4,5)
- s1: scala.collection.immutable.Set[Int] = Set(5, 1, 2, 3, 4)
- scala> val s2 = s1 -1
- s2: scala.collection.immutable.Set[Int] = Set(5, 2, 3, 4)
- scala> val s3 = s2 - (2,3)
- s3: scala.collection.immutable.Set[Int] = Set(5, 4)
- scala> val s4 = s3 -- Array(4,5)
- s4: scala.collection.immutable.Set[Int] = Set()
3. 使用可排序集
1)SortedSet 返回元素时有序的.
- scala> val s = scala.collection.SortedSet(3,1,2,5,6,9)
- s: scala.collection.SortedSet[Int] = TreeSet(1, 2, 3, 5, 6, 9)
- scala> val s = scala.collection.SortedSet("c","g","a","b")
- s: scala.collection.SortedSet[String] = TreeSet(a, b, c, g)
2)LinkedHashSet 按照插入顺序保存元素的.
- scala> val s = scala.collection.mutable.LinkedHashSet(10,8,3,5,7)
- s: scala.collection.mutable.LinkedHashSet[Int] = Set(10, 8, 3, 5, 7)
来源: https://www.cnblogs.com/zhaohadoopone/p/9534982.html