Inside Jetpack Architecture Components

How LifecycleObservers, LiveData, ViewModels work

Transcript

1. )JSPZVLJ
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   !NPSJESPJE *OTJEF
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2.  "
   7FOUVSF
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3. "SDIJUFDUVSF
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4. -JGFDZDMFT -JWF%BUB 7JFX.PEFM 3PPN 1BHJOH %BUB
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6. -JGFDZDMFT -JWF%BUB 7JFX.PEFM 3PPN 1BHJOH %BUB
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7. -JGFDZDMF
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8. JO
   FBSMZ
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9. UPEBZ խ
10. DBTF
    
    UPVDIJOH
    EFTUSPZFE
    7JFX
11. DBTF
    
    UPVDIJOH
    EFTUSPZFE
    7JFX 
12. DBTF
    
    UPVDIJOH
    EFTUSPZFE
    7JFX   Cute Cat
13. DBTF
    
    UPVDIJOH
    EFTUSPZFE
    7JFX   Cute Cat 
14. Cute Cat DBTF
    
    UPVDIJOH
    EFTUSPZFE
    7JFX     
15. DBTF
    
    UPVDIJOH
    EFTUSPZFE
    7JFX       Cute Cat
16. DBTF
    
    UPVDIJOH
    EFTUSPZFE
    7JFX       Cute Cat   
17. DBTF
    
    UPVDIJOH
    EFTUSPZFE
    7JFX       Cute Cat    
18. DBTF
    
    UPVDIJOH
    EFTUSPZFE
    7JFX       Cute Cat     
19. DBTF
    
    GFUDIJOH
    BU
    FWFSZ
    PO$SFBUF
20. Cute Cat DBTF
    
    GFUDIJOH
    BU
    FWFSZ
    PO$SFBUF   
21. The Japanese Bobtail is a breed of domestic cat with an unusual "bobbed" tail more closely resembling the tail of a rabbit than that of other cats. The variety is native to Japan and Southeast Asia, though it is now found throughout the world. The breed has been known in Japan for centuries, and it frequently appears in traditional folklore and art. Short Hair • Brown • White • Cute Caption Japanese Bobtail Cute Cat DBTF
    
    GFUDIJOH
    BU
    FWFSZ
    PO$SFBUF     
22. DBTF
    
    GFUDIJOH
    BU
    FWFSZ
    PO$SFBUF       Cute Cat
23. DBTF
    
    GFUDIJOH
    BU
    FWFSZ
    PO$SFBUF       Cute Cat    
24. DBTF
    
    GFUDIJOH
    BU
    FWFSZ
    PO$SFBUF       Cute Cat     
25.  Cute Cat DBTF
    
    GFUDIJOH
    BU
    FWFSZ
    PO$SFBUF           
26. DBTF
    
    EJTQPTJOH
    JO
    XSPOH
    XBZ
27.  DBTF
    
    EJTQPTJOH
    JO
    XSPOH
    XBZ Cute Cat Cute Cat
28. Cute Cat Cute Cat  DBTF
    
    EJTQPTJOH
    JO
    XSPOH
    XBZ 
29. Cute Cat Cute Cat  DBTF
    
    EJTQPTJOH
    JO
    XSPOH
    XBZ  
30. The Japanese Bobtail is a breed of domestic cat with an unusual "bobbed" tail more closely resembling the tail of a rabbit than that of other cats. The variety is native to Japan and Southeast Asia, though it is now found throughout the world. The breed has been known in Japan for centuries, and it frequently appears in traditional folklore and art. Short Hair • Brown • White • Cute Caption Japanese Bobtail Cute Cat  DBTF
    
    EJTQPTJOH
    JO
    XSPOH
    XBZ       
31. The Japanese Bobtail is a breed of domestic cat with an unusual "bobbed" tail more closely resembling the tail of a rabbit than that of other cats. The variety is native to Japan and Southeast Asia, though it is now found throughout the world. The breed has been known in Japan for centuries, and it frequently appears in traditional folklore and art. Short Hair • Brown • White • Cute Caption Japanese Bobtail Cute Cat  DBTF
    
    EJTQPTJOH
    JO
    XSPOH
    XBZ        
32. Cute Cat Cute Cat  DBTF
    
    EJTQPTJOH
    JO
    XSPOH
    XBZ    
33. Cute Cat Cute Cat  DBTF
    
    EJTQPTJOH
    JO
    XSPOH
    XBZ     
34. 4P
    XIBU
    XF
    TIPVE
35. DBTF
    
    UPVDIJOH
    EFTUSPZFE
    7JFX DBTF
    
    GFUDIJOH
    BU
    FWFSZ
    PO$SFBUF DBTF
    
    EJTQPTJOH
    JO
    XSPOH
    XBZ
36. DBTF
    
    UPVDIJOH
    EFTUSPZFE
    7JFX DBTF
    
    GFUDIJOH
    BU
    FWFSZ
    PO$SFBUF DBTF
    
    EJTQPTJOH
    JO
    XSPOH
    XBZ -JWF%BUB 7JFX.PEFMT -JWF%BUB
    
    7JFX.PEFMT
37. -JGFDZDMF0CTFSWFS
38.  
39.    
40.        
41. TVCTDSJCF TVCTDSJCF        
42. TVCTDSJCF TVCTDSJCF         FWFOU
    IBQQFOT
43. SF
    FWFOUT SF
    FWFOUT         FWFOU
    IBQQFOT
44.  
45.   
46.    
47.    
48.   
49.    
50.     
51.      
52.          
53.        
54.        
55.         &WFOU
    $IBOOFM
56.        
57.         1VCMJTIFS
58.        
59.        
60.        
61.      
62. -JGFDZDMF0CTFSWFS ٥0CTFSWF
    MJGFDZDMFT ٥%FTJHOFE
    BT
    1VC4VC ٥#PJMFSQMBUFGSFF ٥-JGFDZDMF"XBSF
    $PNQPOFOU
63. -JWF%BUB
64.    
65.       
66.         
67.   
68.    
69.       
70.        
71.         0O4UBSUFE
    0O3FTVNFE
72.          0O4UBSUFE
    0O3FTVNFE
73.          0O1BVTFE
74.          0O1BVTFE #MPDL
75.          0O%FTUSPZFE
76.          0O%FTUSPZFE
77. -JWF%BUB ٥0CTFSWBCMF
    EBUB
    IPMEFS ٥-JGFDZDMF"XBSF ٥/P
    MFBL
78. 7JFX.PEFM
79.    
80.     
81.      
82.       
83.      
84.       
85.        
86.     
87.      
88.      
89.  /PO$POHVSBUJPO*OTUBODF
90.      
91.       
92.       
93.       
94. 7JFX.PEFM ٥%BUB
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95. )PX
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96. TUFQ
    
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97. dependencies { implementation fileTree(dir: 'libs', include: ['*.jar']) implementation"org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version" implementation 'androidx.appcompat:appcompat:1.0.0-rc02' implementation 'androidx.constraintlayout:constraintlayout:1.1.3' } -JGFDZDMFT
98. dependencies { … def lifecycle_version = "2.0.0-rc01" implementation "androidx.lifecycle:lifecycle-extensions:$lifecycle_version" } -JWF%BUB
    
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99. apply plugin : 'kotlin-kapt' dependencies { … def lifecycle_version = "2.0.0-rc01" implementation "androidx.lifecycle:lifecycle-extensions:$lifecycle_version" kapt "androidx.lifecycle:lifecycle-compiler:$lifecycle_version" } -JGFDZDMF0CTFSWFS
100. dependencies { ... implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:0.22.5" implementation "org.jetbrains.kotlinx:kotlinx-coroutines-android:0.22.5" implementation "com.squareup.okhttp3:okhttp:3.10.0" implementation "com.squareup.okhttp3:logging-interceptor:3.10.0" implementation "com.squareup.retrofit2:retrofit:2.4.0" implementation "com.squareup.retrofit2:converter-gson:2.4.0" implementation 'com.jakewharton.retrofit:retrofit2-kotlin-coroutines-experimental-adapter:1.0.0' implementation 'com.google.code.gson:gson:2.8.2' implementation 'androidx.recyclerview:recyclerview:1.0.0-rc02' } kotlin { experimental { coroutines "enable" } }
101. TUFQ
     
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102. class YourViewModel : ViewModel() { }
103. class YourViewModel : ViewModel() { }
104. class YourViewModel : ViewModel() { private val _repos = MutableLiveData<List<Repository>>() }
105. class YourViewModel : ViewModel() { private val _repos = MutableLiveData<List<Repository>>() }
106. class YourViewModel : ViewModel() { private val _repos = MutableLiveData<List<Repository>>() }
107. class YourViewModel : ViewModel() { private val _repos = MutableLiveData<List<Repository>>() val repositories : LiveData<List<Repository>> }
108. class YourViewModel : ViewModel() { private val _repos = MutableLiveData<List<Repository>>() val repositories : LiveData<List<Repository>> get() { if (_repos.value == null) { val repos = github.repositories() _repos.postValue(repos) } return _repos } }
109. class YourViewModel : ViewModel() { private val _repos = MutableLiveData<List<Repository>>() val repositories : LiveData<List<Repository>> get() { if (_repos.value == null) { val repos = github.repositories() _repos.postValue(repos) } return _repos } }
110. class YourViewModel : ViewModel() { private val _repos = MutableLiveData<List<Repository>>() val repositories : LiveData<List<Repository>> get() { if (_repos.value == null) { val repos = github.repositories() _repos.postValue(repos) } return _repos } }
111. class YourViewModel : ViewModel() { private val _repos = MutableLiveData<List<Repository>>() val repositories : LiveData<List<Repository>> get() { if (_repos.value == null) { val repos = github.repositories() _repos.postValue(repos) } return _repos } }
112. class YourViewModel : ViewModel() { private val _repos = MutableLiveData<List<Repository>>() val repositories : LiveData<List<Repository>> get() { if (_repos.value == null) { // Coroutine way launch(CommonPool) { val repos = github.repositories().await() _repos.postValue(repos) } } return _repos } }
113. class YourViewModel : ViewModel() { private val _repos = MutableLiveData<List<Repository>>() val repositories : LiveData<List<Repository>> get() { if (_repos.value == null) { // Rx way github.repositories() .observeOn(AndroidSchedulers.mainThread()) .subscribeOn(Schedulers.io()) .subscribe { repositories.postValue(it) } } return _repos } }
114. TUFQ
     
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115. class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { ... val viewModel = ViewModelProviders.of(this)[YourViewModel::class.java] } }
116. class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { ... val viewModel = ViewModelProviders.of(this)[YourViewModel::class.java] viewModel.repositories.observe(this, Observer { // update Views }) } }
117. $PODMVTJPO
118. -JGFDZDMF
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119. )JSPZVLJ
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