时间：2020-11-27 11:21:14 | 栏目：JAVA代码 | 点击：次
1.mkString()方法的使用：
object Test {
def main(args: Array[String]): Unit = {
var name : String = "Hello LittleLawson"
var age :Int = 2
println(name.mkString)
println(name.mkString(" "))//separate string with space
var str0 = "scala"
println(str0.mkString(","))//separate string with comma
println(str0.mkString("begin",",","end"))
/*
1.mkString is used in the inner List,That is say ,Elements in the list is applied.
*/
val a = List(1,2,3,4)
val b = new StringBuilder()
println(a.mkString("List(" , ", " , ")"))
}
}
执行结果如下：
Hello LittleLawson
H e l l o L i t t l e L a w s o n
s,c,a,l,a
begins,c,a,l,aend
List(1, 2, 3, 4)Process finished with exit code 0
2.scala通过mkString方法把一个集合转化为一个字符串
Problem
如果你想要把集合元素转化为字符串，可能还会添加分隔符，前缀，后缀。
Solution
使用mkString方法来打印一个集合内容，下面给一个简单的例子：
scala> val a = Array("apple", "banana", "cherry")
a: Array[String] = Array(apple, banana, cherry)
scala> a.mkString
res3: String = applebananacherry
使用mkString方法你会看到结果并不漂亮，我们来加一个分隔符：
scala> a.mkString(",")
res4: String = apple,banana,cherry
scala> a.mkString(" ")
res5: String = apple banana cherry
这样看起来就好看多了，同样你可以添加一个前缀和一个后缀：
scala> a.mkString("[", ", ", "]")
res6: String = [apple, banana, cherry]
如果你想把一个潜逃集合转化为一个字符串，比如嵌套数组，首先你要展开这个嵌套数组，然后调用mkString方法：
scala> val a = Array(Array("a", "b"), Array("c", "d"))
a: Array[Array[String]] = Array(Array(a, b), Array(c, d))
scala> a.flatten.mkString(",")
res7: String = a,b,c,d
Discussion
你可以调用集合的toString方法，但是它返回带有集合元素信息的集合名称：
scala> val v = Vector("apple", "banana", "cherry")
v: scala.collection.immutable.Vector[String] = Vector(apple, banana, cherry)
scala> v.toString
res8: String = Vector(apple, banana, cherry)