This document discusses Android data binding. It begins by explaining what data binding is and providing simple examples of how to bind data to views using strings, objects, and variables. It then covers more advanced topics like creating a data binding class, setting variable values, two-way binding, binding adapters, using data binding with RecyclerView, and the performance benefits of data binding.

2. Project
https://github.com/awonwon/gdgk-
databinding-sample

3. DataBinding
@GDG Kaohsiung

4. 我是誰？
awonwon
25sprout Android
HITCON GIRLS

6. Android Studio 2.0 ^^?

8. What is Data Binding?
TextView
String show = "Hello"
DataBinding
Layout Activity

9. What is Data Binding?
Hello
TextView
String show = "Hello"
binding.set (show);
DataBinding
Layout Activity

10. What is Data Binding?
GGWP
TextView
Show="GGWP";
DataBinding
Layout Activity

11. Layout Activity
Binding With POJO
Name
TextView
DataBinding
Tel
TextView
Tel
TextView
User user = new User();
binding.set (user);

12. Clean Code
Zero Reflection
Official Library
MMVM

13. YEAH

14. main_layout
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/
android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/view_id"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text=""/>
<TextView
android:id="@+id/view_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text=""/>
< TextView …
</LinearLayout>
LinearLayout
{id}
{name}
{level}
{exp}

15. MainActivity
LinearLayout
{id}
{name}
{level}
{exp}
private TextView idView, nameView, levelView, expView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_layout);
findViews();
User user = new User("8591", " ", "5",
"2000");
idView.setText(user.id);
nameView.setText(user.name);
levelView.setText("LV." + user.level);
expView.setText(user.exp);
}
private void findViews(){
idView = (TextView) findViewById(R.id.view_id);
nameView = (TextView) findViewById(R.id.view_name);
levelView = (TextView) findViewById(R.id.view_level);
expView = (TextView) findViewById(R.id.view_exp);
}

16. MainActivity
LinearLayout
8591
LV.5
2000
private TextView idView, nameView, levelView, expView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_layout);
findViews();
User user = new User("8591", " ", "5","2000"
idView.setText(user.id);
nameView.setText(user.name);
levelView.setText("LV." + user.level);
expView.setText(user.exp);
}
private void findViews(){
idView = (TextView) findViewById(R.id.view_id);
nameView = (TextView) findViewById(R.id.view_name);
levelView = (TextView) findViewById(R.id.view_level);
expView = (TextView) findViewById(R.id.view_exp);
}

17. DataBinding

18. Build.gradle
android {
compileSdkVersion 23
buildToolsVersion "23.0.2"
defaultConfig {
applicationId "com.sprout.give"
minSdkVersion 15
targetSdkVersion 23
versionCode 1
versionName "1.0"
}
dataBinding {
enabled = true
}
}
DataBinding

19. <?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/view_id"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text=""/>
<TextView
android:id="@+id/view_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text=""/>
< TextView …
</LinearLayout>
</layout>
main_layout
LinearLayout
{id}
{name}
{level}
{exp}
Root View <Layout>

20. <?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data class="MainActivityDataBinding">
<import type="com.awonwon.User"/>
<variable
name="user"
type="user"/>
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/view_id"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text=""/>
<TextView
android:id="@+id/view_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text=""/>
< TextView …
</LinearLayout>
</layout>
main_layout
LinearLayout
{id}
{name}
{level}
{exp}
& Import Class

21. <?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data class="MainActivityDataBinding">
<import type="com.awonwon.User"/>
<variable
name="user"
type="user"/>
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/view_id"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{user.id}"/>
<TextView
android:id="@+id/view_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{user.name}"/>
< TextView …
</LinearLayout>
</layout>
main_layout
LinearLayout
{user.id}
{user.name}
{user.level}
{user.exp}
binding @{value}

22. MainActivity
LinearLayout
{user.id}
{user.name}
{user.level}
{user.exp}
public class MainAcivity extends AppCompatActivity{
private TextView idView, nameView, levelView, expView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main_layout);
findViews();
User user = new User("8591", " ", "5", "2000");
idView.setText(user.id);
nameView.setText(user.name);
levelView.setText("LV." + user.level);
expView.setText(user.exp);
}
private void findViews(){
idView = (TextView) findViewById(R.id.view_id);
nameView = (TextView) findViewById(R.id.view_name);
levelView = (TextView) findViewById(R.id.view_level);
expView = (TextView) findViewById(R.id.view_exp);
}
}

23. LinearLayout
8591
LV.5
2000
MainActivity public class MainAcivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MainActivityDataBinding binding =
DataBindingUtil.setContentView(
this, R.layout.main_layout);
User user = new User("8591", " ", "5", "2000");
binding.setUser(user);
}
BindingClass & Value

24. findView
｡:.ﾟ (*´∀`)ﾉﾟ.:｡

26. Layout
View
DataBinding
Class

27. Layout
Data Binding
BindingClass
BindinClass
tag
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{"Lv."+user.level}"/>
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{"Lv."+user.level}"/>
"Lv." + user.level
=> LV.5
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text=""
android:tag="binding_1"/>

28. DataBinding Class
intermediatesclassesdebug[package_name]databinding
Binding Layout
intermediatesdata-binding-layout-outdebuglayout
buildintermediates

29. <layout
xmlns:android="http://schemas.android.com/apk/res/android">
<data class="MainActivityDataBinding">
<import type="com.awonwon.User"/>
<variable
name="user"
type="user"/>
</data>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@{user.id}"/>
< …
</LinearLayout>
</layout>
Initialize variable
Set value
Layout

30. 1. Initialize Variable
<data class="com.awonwon.MainActivityBinding">
<import type="com.awonwon.model.User" />
<import type="android.view.View" alias="v" />
<variable name="user" type="User" />
<variable name="datetime" type="String" />
<variable name="position" type="int" />
</data>

31. MainActivityBinding …
private com.awonwon.model.User mUser;
private String mDatetime;
private int mPotision;
private com.awonwon.model.User getUser();
private void setUser(com.awonwon.model.User user);
private String getDatetTime();
private void setDateTime(String datetime);
private int getPosition();
private void setPosition(int position);

32. 2. Set Value Example
android:text="@{user.lastName}"
android:text="@{MyStringUtils.capitalize(user.firstName)}"
android:visibility="@{user.isAdult ? View.VISIBLE : View.GONE}"
android:padding="@{large? @dimen/largePadding :
(int)@dimen/smallPadding}"

33. Null Coalescing
android:text="@{user.displayName ?? user.lastName}"
android:text="@{user.displayName != null ? user.displayName : user.lastName}"

34. • + - / * %
• +
• && || & | ^
• + - ! ~
• >> >>> <<
• == > < >= <=
• instanceof
• ()
• null
• Cast
•
• List Array Map
• ?:
※ XML encode : & = &amp;

35. <TextView android:text='@users.age > 18 ?
user.name.substring(0,1).toUpperCase() + "." +
user.lastName : @string/redacted'/>

36. BindAdapter
layout attribute
<ImageView
...
app:imageUrl="@{user.avatarUrl}
...
/>

37. BindAdapter
src field
@BindingAdapter(value = {"app:imageUrl"}, requireAll = true)
public static void loadImgUrl(ImageView view, String path){
Picasso.with(view.getContext())
.load(path)
.fit()
.centerCrop()
.into(view);
}

38. ID?
• static final MainActivityDataBinding
<TextView
android:id="@+id/view_name"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text=""/>
public final TextView view_name;

39. JAVA Class
public class MainAcivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MainActivityDataBinding binding = DataBindingUtil.setContentView(
this, R.layout.main_layout);
User user = new User("8591", " ", "5", "2000");
binding.setUser(user);
}
}

40. DataBinding
public class MainAcivity extends AppCompatActivity{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
MainActivityDataBinding binding = DataBindingUtil.setContentView(
this, R.layout.main_layout);
User user = new User("8591", " ", "5", "2000");
binding.setUser(user);
}
}
Create DataBinding Class
Set Variable Value

41. 1. Create DataBinding Class
MainActivityDataBinding binding = DataBindingUtil.setContentView(
this, R.layout.main_layout);
ItemBinding binding = DataBindingUtil.inflate(LayoutInflater.from(c),
R.layout.item, parent, false);

42. 2. Set Variable Value
binding.setUser(user);
binding.setVariable(BR.user, user);

43. …
Object Value

44. Observable Binding
1. BaseObservable & set method notifyPropertyChanged
public class User extends BaseObservable {
private String name;
@Bindable
public String getName() {
return name;
}
public void setLastName(String name) {
this.name = name;
notifyPropertyChanged(BR.name);
}

45. Observable Binding
2. ObservableField<T>
public final ObservableField<ItemAdapter> mItemAdapter = new ObservableField<>();
mItemAdapter.get().updateData(items);
mItemAdapter.set(adapter);

46. RecyclerAdapter
public class ItemViewHolder extends RecyclerView.ViewHolder {
private ItemBinding binding;
public ItemViewHolder(View itemView) {
super(itemView);
binding = DataBindingUtil.bind(itemView);
}
public ItemBinding getBinding(){
return binding;
}
public void setBinding(ItemBinding binding){
this.binding = binding;
}
}

47. RecyclerAdapter
@Override
public ItemViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
GalleryItemBinding binding = DataBindingUtil.inflate(LayoutInflater.from(c),
R.layout.item_gallery, parent, false);
ItemViewHolder holder = new ItemViewHolder(binding.getRoot());
holder.setBinding(binding);
return holder;
}
@Override
public void onBindViewHolder(ItemViewHolder holder, int position) {
holder.binding.setItem(mItems.get(position));
holder.binding.setPosition(position);
if (getItemViewType(position)==TYPE_SELECTED) {
holder.binding.setSelected(true);
}
holder.binding.executePendingBindings();
}

48. EditText
Two-Way Binding

49. Two-Way Binding
•Android Studio 2.1 Preview 3
<EditText android:text="@={user.name}" .../>
dependencies {
classpath 'com.android.tools.build:gradle:2.1.0-alpha3'
}
https://halfthought.wordpress.com/2016/03/23/2-way-data-binding-on-android/

50. DataBinding

51. Clean Code
Zero Reflection
Official Library
MMVM

52. Clean Code
Zero Reflection
Official Library
MMVM

53. Performance
• findViewById V.S. DataBinding
• findViewById
View
• DataBinding
Compiler Timer
View
RootView
LinearLayout
ImageView
RelativeLayout
TextView
LinearLayout
TextView
ImageView

54. Q&A

55. DataBinding Google I/O
https://realm.io/news/data-binding-android-boyar-mount/