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不可变Set
- 创建Set
scala> val a=Set(1,1,2,3)
a: scala.collection.immutable.Set[Int] = Set(1, 2, 3)
- 添加元素
scala> a+(4)
res119: scala.collection.immutable.Set[Int] = Set(1, 2, 3, 4)
scala> a++List(5,6)
res121: scala.collection.immutable.Set[Int] = Set(5, 1, 6, 2, 3)
需要注意的是,加了一些元素之后,对于a是否会变化。主要到scala.collection.immutable
可变Set
- 初始化
scala> val mutableSet =Set(1,2,3)
mutableSet: scala.collection.mutable.Set[Int] = Set(1, 2, 3)
- 加元素
scala> mutableSet+(4)
res141: scala.collection.mutable.Set[Int] = Set(1, 2, 3, 4)
scala> mutableSet
res142: scala.collection.mutable.Set[Int] = Set(1, 2, 3)
scala> mutableSet.add(4)
res143: Boolean = true
scala> mutableSet
res144: scala.collection.mutable.Set[Int] = Set(1, 2, 3, 4)
scala>
注意区别
-删除元素
scala> mutableSet-(4)
res146: scala.collection.mutable.Set[Int] = Set(1, 2, 3)
scala> mutableSet
res147: scala.collection.mutable.Set[Int] = Set(1, 2, 3, 4)
scala> mutableSet.remove(4)
res148: Boolean = true
scala> mutableSet
res149: scala.collection.mutable.Set[Int] = Set(1, 2, 3)
scala>
实际用的时候要注意是否对Set本身操作,要记得变和不变的区别。