kotlin: 新添加fragment

一，添加fragment

fragment的ui

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".fragment.UserListFragment">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:text="获取Json" />

</LinearLayout>

把fragment添加到activity的ui中

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <fragment
        android:id="@+id/leftfrag"
        android:name="com.example.okdemo2.fragment.UserListFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:ignore="MissingConstraints" />


</androidx.constraintlayout.widget.ConstraintLayout>

二，运行后测试效果: