[Koltin Flow (1)] Five ways to create flow

前言

1. flow is the asynchronous version of the sequence,This is a collection type,The values ​​in it are generated one by one.与序列一样,Only when a certain value is required,flow This value is generated on demand,而且 flow Can contain an unlimited number of values.
2. Simply put, it is streaming,用过Rxwill be easier to understand.
3. flow通过apiand coroutine support,It is more convenient to deal with reactive programming.

创建方式

创建方式1 flow{}

代码如下

		flow {
    
              repeat(10){
    
                    delay(10)
                    emit(it)
                }
            }.collect {
    
                Log.d(TAG.TAG,"method 1 it is $it")
            }

日志如下：

2022-07-28 17:05:01.070 3699-3724/edu.test.demo D/Test-TAG: method 1 it is 0
2022-07-28 17:05:01.080 3699-3724/edu.test.demo D/Test-TAG: method 1 it is 1
2022-07-28 17:05:01.091 3699-3724/edu.test.demo D/Test-TAG: method 1 it is 2
2022-07-28 17:05:01.106 3699-3724/edu.test.demo D/Test-TAG: method 1 it is 3
2022-07-28 17:05:01.130 3699-3724/edu.test.demo D/Test-TAG: method 1 it is 4
2022-07-28 17:05:01.140 3699-3724/edu.test.demo D/Test-TAG: method 1 it is 5
2022-07-28 17:05:01.153 3699-3724/edu.test.demo D/Test-TAG: method 1 it is 6
2022-07-28 17:05:01.163 3699-3724/edu.test.demo D/Test-TAG: method 1 it is 7
2022-07-28 17:05:01.174 3699-3724/edu.test.demo D/Test-TAG: method 1 it is 8
2022-07-28 17:05:01.186 3699-3724/edu.test.demo D/Test-TAG: method 1 it is 9

创建方式2 flowof

代码如下

            flowOf(1,2,3,4,5).collect {
    
                Log.d(TAG.TAG,"method 2 it is $it")
            }

日志如下：

2022-07-28 17:05:01.187 3699-3724/edu.test.demo D/Test-TAG: method 2 it is 1
2022-07-28 17:05:01.187 3699-3724/edu.test.demo D/Test-TAG: method 2 it is 2
2022-07-28 17:05:01.187 3699-3724/edu.test.demo D/Test-TAG: method 2 it is 3
2022-07-28 17:05:01.187 3699-3724/edu.test.demo D/Test-TAG: method 2 it is 4
2022-07-28 17:05:01.187 3699-3724/edu.test.demo D/Test-TAG: method 2 it is 5

创建方式3 asFlow

代码如下

    listOf(6,7,8,9,10).asFlow().collect {
    
                Log.d(TAG.TAG,"method 3 it is $it")
            }

日志如下：

2022-07-28 17:05:01.204 3699-3724/edu.test.demo D/Test-TAG: method 3 it is 6
2022-07-28 17:05:01.204 3699-3724/edu.test.demo D/Test-TAG: method 3 it is 7
2022-07-28 17:05:01.204 3699-3724/edu.test.demo D/Test-TAG: method 3 it is 8
2022-07-28 17:05:01.204 3699-3724/edu.test.demo D/Test-TAG: method 3 it is 9
2022-07-28 17:05:01.204 3699-3724/edu.test.demo D/Test-TAG: method 3 it is 10

创建方式4 channelFlow{}

代码如下

	channelFlow {
    
                repeat(10){
    
                    delay(10)
                    send(it)
                }
            }.collect {
    
                Log.d(TAG.TAG,"method 4 it is $it")
            }

日志如下：

2022-07-28 17:05:01.227 3699-3724/edu.test.demo D/Test-TAG: method 4 it is 0
2022-07-28 17:05:01.238 3699-3724/edu.test.demo D/Test-TAG: method 4 it is 1
2022-07-28 17:05:01.250 3699-3724/edu.test.demo D/Test-TAG: method 4 it is 2
2022-07-28 17:05:01.260 3699-3724/edu.test.demo D/Test-TAG: method 4 it is 3
2022-07-28 17:05:01.272 3699-3725/edu.test.demo D/Test-TAG: method 4 it is 4
2022-07-28 17:05:01.284 3699-3725/edu.test.demo D/Test-TAG: method 4 it is 5
2022-07-28 17:05:01.295 3699-3725/edu.test.demo D/Test-TAG: method 4 it is 6
2022-07-28 17:05:01.306 3699-3725/edu.test.demo D/Test-TAG: method 4 it is 7
2022-07-28 17:05:01.317 3699-3725/edu.test.demo D/Test-TAG: method 4 it is 8
2022-07-28 17:05:01.329 3699-3724/edu.test.demo D/Test-TAG: method 4 it is 9

创建方式5 callbackFlow{}

代码如下

 callbackFlow<String> {
    
                delay(100)
                trySendBlocking("123456")
                awaitClose {
      }
            }.collect {
    
                Log.d(TAG.TAG,"method 5 it is $it")
            }

日志如下：

2022-07-28 17:05:01.438 3699-3724/edu.test.demo D/Test-TAG: method 5 it is 123456

总结

本篇主要介绍flowThe basic creation part of ,Five ways are introduced,因为内容比较简单,Introduction is less,It is also easier to understand directly on the code.