为什么不为布局创建"Binding"

Question

我创建了为" registerivity.java"的名称创建的活动，但是，为什么" activyRegisterBinding"尚未创建？交织，我在创建" registerivity.java"之前，我正在创建活动" loginactivity.java"，并具有" activyLoginBinding"。可以解释我吗？

这是registerivity.java的布局：

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".view.RegisterActivity">
</android.support.constraint.ConstraintLayout>

和登录布局：

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">
    <data>
        <variable
            name="MyViewModel"
            type="com.example.questionandanswer.viewModel.MyViewModel" />
    </data>
    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:isScrollContainer="true">
        <android.support.constraint.ConstraintLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            tools:context=".View.MainActivity">
            <EditText
                android:id="@+id/txtEmailAddress"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginStart="32dp"
                android:layout_marginTop="80dp"
                android:layout_marginEnd="32dp"
                android:layout_marginBottom="16dp"
                android:ems="10"
                android:hint="E-Mail Address"
                android:inputType="textEmailAddress"
                android:text="@={MyViewModel.EmailAddress}"
                app:layout_constraintBottom_toTopOf="@+id/txtPassword"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent" />
            <EditText
                android:id="@+id/txtPassword"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginEnd="32dp"
                android:layout_marginStart="32dp"
                android:layout_marginTop="16dp"
                android:ems="10"
                android:hint="Password"
                android:inputType="textPassword"
                android:text="@={MyViewModel.Password}"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/txtEmailAddress" />
            <Button
                android:id="@+id/btnLogin"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_marginEnd="32dp"
                android:layout_marginStart="32dp"
                android:layout_marginTop="32dp"
                android:text="Click to Login"
                android:onClick="@{(v) -> MyViewModel.onClick(v)}"
                android:textSize="18sp"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toBottomOf="@+id/txtPassword" />
            <android.support.v7.widget.Toolbar
                android:id="@+id/toolbar2"
                android:layout_width="416dp"
                android:layout_height="wrap_content"
                android:background="?attr/colorPrimary"
                android:minHeight="?attr/actionBarSize"
                android:theme="?attr/actionBarTheme"
                app:layout_constraintEnd_toEndOf="parent"
                app:layout_constraintStart_toStartOf="parent"
                app:layout_constraintTop_toTopOf="parent" />
        </android.support.constraint.ConstraintLayout>
    </android.support.v4.widget.NestedScrollView>
</layout>

谢谢

Answer 1

activity_register.xml需要包裹在 <layout> tag

中

<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">
    <android.support.constraint.ConstraintLayout     
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".view.RegisterActivity">
    </android.support.constraint.ConstraintLayout>
</layout>

是<layout>告诉DataBinding插件生成绑定代码。