This document discusses data binding in Android. It introduces data binding as a way to bind data model objects to UI elements to remove unnecessary code. It describes how to set up data binding by preparing a model, layout, and connecting them in an activity. It also covers some features like importing classes, supporting resources, and expression languages. Finally, it notes some current problems with data binding like poor IDE support and that the API is still in beta.

1. Data Binding
2015-OCTOBER-2ND
LAY Leangsros

2. Outline
I. Introduction
II. Using
III. Features
IV. Problems
2

3. Introduction
What is Data Binding?
- Data binding binds a data model object to a UI elements
- Announced at Google I/O 2015
Model Binding View
3

4. Introduction
Why do we need it?
- Remove unnecessary code ( add…Listener, findViewById, setText)
- Aid Memory Management
- Value code quality
4

5. Introduction
Why do we need it?
- Remove unnecessary code ( add..Listener, findViewById, setText)
5
@Override
public void onBindViewHolder(MyViewHolder holder, final int position) {
holder.getmItemBinding().setUser(mUserList.get(position));
holder.getmItemBinding().executePendingBindings();
}
@Override
public void onBindViewHolder(MyViewHolder holder, final int position) {
holder.name.setText(..);
holder.age.setText(..);
...
}
N
1

6. Introduction
Why do we need it?
- Aid Memory Management
- Value code quality
6

7. Using
What do we need?
- Minimum API-level 7 (2.1)
- Android Studio 1.3.0 or higher
- Add library in root build.gradle
- Apply plugin in build.gradle app
dependencies {
..
classpath "com.android.databinding:dataBinder:1.0-rc1"
}
apply plugin: 'com.android.databinding'
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8. Using
How do we use?
- Preparing the Model
- Preparing the Layout
- Connect Model and Layout in your activity
8

9. Using
How do we use?
9
User.java MainActivity.java
ExampleLayoutBinding
Handler.java
ExampleLayoutBinding.java
public void setHandler(Handler handler);
public void setUser(User user);
…….
example_layout.xml
handler
user

10. Using
How do we use?
10
public class User extends BaseObservable{
public String name;
public int age;
//Setter and Getter
}
<layout xmlns:android="http://schemas.android.com/apk/res/android">
<data>
<variable name="user" type="com.dmi.bindingview.User"/>
</data>
<RelativeLayout
......
<TextView
......
android:text="@{user.name}"/>
</RelativeLayout>
</layout>
private ActivityMainBinding mBinding;
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mBinding = DataBindingUtil.setContentView(this, R.layout.activity_main);
mBinding.setUser(mUser);
}
}
User.java
activity_main.xml
MainActivity.class

11. Features
More Features
- Imports Classes
- Supporting Resources
- Expression Languages
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12. Features
More Features
- Imports Classes
12
..
<layout
..
<data>
<import type="android.view.View"/>
<variable name="user" type="com.dmi.bindingview.User"/>
</data>
<LinearLayout
.. >
<TextView
..
android:visibility="@{user.age>20 ? View.VISIBLE : View.GONE}"/>
</LinearLayout>
</layout>

13. Features
More Features
- Supporting Resources
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android:text="@{@string/nameFormat(firstName, lastName)}"
android:text="@{@plurals/banana(bananaCount)}"
android:padding="@{@dimen/largePadding}"
android:textColor="@{@color/red}"

14. Features
More Features
- Expression Languages
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• Mathematical + - / * %
• String concatenation +
• Logical && ||
• Binary & | ^
• Unary + - ! ~
• Shift >> >>> <<
• Comparison == > < >= <=
• instanceof
• Grouping ()
• Literals - character, String, numeric, null
• Cast
• Method calls
• Field access
• Array access []
• Ternary operator ?:
It is like Java expressions

15. Problems
Current Problems
- IDE-Support currently poor
* Error indicated, but it compiles and works
* No code completion in layout
- API not stable, it is in beta.
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16. Demo
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17. References
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- Documentation: https://developer.android.com/tools/data-binding/guide.html
- Android Data Binding - Christopher Schott / Florian Fetzer: https://droidcon.gitbooks.io/2015-berlin-
barcamp/content/android_data_binding_-_christopher_schott__florian_fetzer.html
- Import : http://catinean.com/2015/05/31/how-you-can-go-wrong-with-the-new-data-binding-api/
- Google I/O 2015 - What's new in Android (13th min) : https://www.youtube.com/watch?v=ndBdf1_oOGA