Spark算子：map和flatMap区别

scala> val test=List("hello java","hello python","hello hadoop")
test: List[String] = List(hello java, hello python, hello hadoop)

scala> test.map(line=>line).foreach(x=>println(x))
hello java
hello python
hello hadoop

scala> test.flatMap(line=>line.split(" ")).foreach(x=>println(x))
hello
java
hello
python
hello
hadoop

scala> text.flatMap(line=>line).foreach(x=>println(x))
h
e
l
l
o

j
a
v
a
h
……