精选文章 flatmap和map的区别！

flatmap和map的区别！

作者：乔治大哥 时间: 2019-11-06 07:13:25
乔治大哥 2019-11-06 07:13:25
标签： # bigdata_spark flatmap和map的区别！

flatmap和map的源代码：

flatmap和map的区别！1

 

如果你有专门的去写代码观察：

flatmap和map的区别！2

二者的返回值是区别的。大致可以理解：

map：map方法返回的是一个object，map将流中的当前元素替换为此返回值；

flatMap：flatMap方法返回的是一个stream，flatMap将流中的当前元素替换为此返回流拆解的流元素；

原始数据：

class1	100
class2	86
class3	70
class1	102
class2	65
class1	45
class2	85
class3	70
class1	16
class2	88
class1	95
class2	37
class3	98
class1	99
class2	23

两者的输出：

class1
100
class2
86
class3
70
class1
102
class2
65
class1
45
class2
85
class3
70
class1
16
class2
88
class1
95
class2
37
class3
98
class1
99
class2
23
*******************
[Ljava.lang.String;@469dae73
[Ljava.lang.String;@6fba91e7
[Ljava.lang.String;@74fbe02f
[Ljava.lang.String;@bfd93a3
[Ljava.lang.String;@20b85a99
[Ljava.lang.String;@1b36c2c0
[Ljava.lang.String;@3067b311
[Ljava.lang.String;@57605e35
[Ljava.lang.String;@35eeaad2
[Ljava.lang.String;@18e35e6d
[Ljava.lang.String;@1511895b
[Ljava.lang.String;@40d5fc3a
[Ljava.lang.String;@ad66c8
[Ljava.lang.String;@23f4086
[Ljava.lang.String;@1b7d5acb

 

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