迁移到AndroidX

修改gradle.properties
# 当前项目启用Androidx
android.useAndroidX=true
# 将依赖包迁移到androidx
android.enableJetifier=true
点击：Refactor > Migrate to AndroidX，如下图
import android.support.v4.view.ViewPager

import android.support.v4.app.Fragment;

import android.support.v4.app.FragmentManager;

import android.support.v4.app.FragmentPagerAdapter;

import android.support.v4.view.PagerAdapter;

import android.support.v4.view.AccessibilityDelegateCompat;

import android.support.v4.view.MotionEventCompat;

import android.support.v4.view.VelocityTrackerCompat;

import android.support.v4.view.ViewCompat;

import android.support.v4.view.ViewConfigurationCompat;

import android.support.v4.view.accessibility.AccessibilityNodeInfoCompat;

import android.support.v4.view.accessibility.AccessibilityRecordCompat;

import android.support.v4.widget.EdgeEffectCompat;

import android.support.v4.app.DialogFragment;

import android.support.v4.widget.SwipeRefreshLayout;

import android.support.v4.app.FragmentTransaction;

import android.support.v4.content.ContextCompat;

import android.support.v4.app.ActivityCompat;

import android.support.v4.app.NotificationCompat;

import android.support.v4.os.ParcelableCompat;

import android.support.v4.os.ParcelableCompatCreatorCallbacks;

import android.support.v4.view.accessibility.AccessibilityEventCompat;

import android.support.v4.content.FileProvider;

import androidx.fragment.app.Fragment;

import androidx.fragment.app.FragmentManager;

import androidx.fragment.app.FragmentPagerAdapter;

import androidx.viewpager.widget.PagerAdapter;

import androidx.core.view.AccessibilityDelegateCompat;

import androidx.core.view.MotionEventCompat;

import androidx.core.view.VelocityTrackerCompat;

import androidx.core.view.ViewCompat;

import androidx.core.view.ViewConfigurationCompat;

import androidx.core.view.accessibility.AccessibilityNodeInfoCompat;

import androidx.core.view.accessibility.AccessibilityRecordCompat;

import androidx.core.widget.EdgeEffectCompat;

import androidx.fragment.app.DialogFragment;

import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;

import androidx.fragment.app.FragmentTransaction;

import androidx.core.content.ContextCompat;

import androidx.core.app.ActivityCompat;

import androidx.core.app.NotificationCompat;
v7包问题：

import android.support.v7.widget.LinearLayoutManager;

import android.support.v7.widget.LinearSmoothScroller;

import android.support.v7.widget.RecyclerView;

import android.support.v7.widget.AppCompatImageView

import android.support.v7.widget.AppCompatTextView;

import android.support.v7.widget.GridLayoutManager;

android.support.v7.widget.AppCompatSeekBar

import android.support.v7.app.AppCompatActivity;

import androidx.recyclerview.widget.LinearLayoutManager;

import androidx.recyclerview.widget.RecyclerView;

import androidx.recyclerview.widget.LinearSmoothScroller;

import androidx.appcompat.widget.AppCompatImageView;

import androidx.appcompat.widget.AppCompatTextView;

import androidx.recyclerview.widget.GridLayoutManager;

import androidx.appcompat.widget.AppCompatSeekBar;

import androidx.appcompat.app.AppCompatActivity;
注解问题：

import android.support.annotation.Nullable;

import android.support.annotation.IntDef;

import android.support.annotation.ColorInt;

import android.support.annotation.NonNull;

import android.support.annotation.DimenRes;

import android.support.annotation.DrawableRes;

import android.support.annotation.StringRes;

import android.support.annotation.LayoutRes;

import android.support.annotation.IdRes;

import android.support.annotation.FloatRange;

import android.support.annotation.IntRange;

import androidx.annotation.Nullable;

import androidx.annotation.IntDef;

import androidx.annotation.ColorInt;

import androidx.annotation.NonNull;

import androidx.annotation.DimenRes;

import androidx.annotation.DrawableRes;

import androidx.annotation.StringRes;

import androidx.annotation.LayoutRes;

import androidx.annotation.IdRes;
bind：

import android.databinding.BindingAdapter;