額，其實我是想問如何實現：

<EditText

????????????android:onTextChanged="@{()?->?person.onTextChanged(這里面不知道怎么實現)}"

????????????android:layout_width="match_parent"

????????????android:layout_height="wrap_content"?/>

不知道我寫的代碼對不對你的問題。

我的理解是：

在EditText上綁定一個onTextChange事件，每當EditText中輸入的內容改變了，使用Toast顯示出來。

下面貼上我的代碼

//?MainActivity.java
public?class?MainActivity?extends?AppCompatActivity?{

????private?ActivityMainBinding?mBinding;
????private?User?mUser;

????@Override
????protected?void?onCreate(Bundle?savedInstanceState)?{
????????super.onCreate(savedInstanceState);
????????//?setContentView(R.layout.activity_main);
????????mBinding?=?DataBindingUtil.setContentView(this,?R.layout.activity_main);
????????mUser?=?new?User("Oz",?"Young");
????????mBinding.setUser(mUser);
????????mBinding.setPerson(new?Person());
????}

????public?class?Person?{
????????public?void?onClick(User?user)?{
????????????Toast.makeText(MainActivity.this,?user.getFirstName(),?Toast.LENGTH_SHORT).show();
????????}

????????public?void?onTextChanged(CharSequence?s,?int?start,?int?before,?int?count)?{
????????????mUser.setFirstName(s.toString());
????????????mBinding.setUser(mUser);
????????????//?s?就是EditText中輸入的值
????????????//?使用Toast打印
????????????Toast.makeText(MainActivity.this,?s.toString(),?Toast.LENGTH_SHORT).show();
????????}
????}
}

<?xml?version="1.0"?encoding="utf-8"?>
<layout?xmlns:android="http://schemas.android.com/apk/res/android">

????<data>

????????<variable
????????????name="user"
????????????type="com.android.oz.databindingdemo.User"?/>
????????<!--記得這里需要將Person傳遞進來-->
????????<variable
????????????name="person"
????????????type="com.android.oz.databindingdemo.MainActivity.Person"?/>
????</data>

????<LinearLayout
????????android:layout_width="match_parent"
????????android:layout_height="match_parent"
????????android:orientation="vertical">

????????<!--?綁定onTextChanged?-->
????????<!--?這里使用::是為了與.區分開，使用::能清楚的知道是調用方法?-->
????????<EditText
????????????android:onTextChanged="@{person::onTextChanged}"
????????????android:layout_width="match_parent"
????????????android:layout_height="wrap_content"?/>

????????<TextView
????????????android:onClick="@{()?->?person.onClick(user)}"
????????????android:layout_width="match_parent"
????????????android:layout_height="wrap_content"
????????????android:text="@{user.firstName}"?/>

????????<TextView
????????????android:layout_width="match_parent"
????????????android:layout_height="wrap_content"
????????????android:text="@{user.lastName}"?/>
????</LinearLayout>
</layout>