一.ViewPage2添加新特性：
* 从右到左的布局支持
* 垂直方向
* RecyclerView.Adapter取代PagerAdapter
* registerOnPageChangeCallback 取代 addPageChangeListener
* 更高效的notifyDataSetChanged
二.以下案例是使用RecyclerView结合ViewPage2实现上下滑动
1.依赖导入
//ViewPage2
implementation 'androidx.viewpager2:viewpager2:1.0.0-alpha01'
//recyclerview
implementation 'androidx.recyclerview:recyclerview:1.0.0-beta01'
2.Activity和Adapter布局设置
1>.Activity布局
<?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:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.viewpager2.widget.ViewPager2
android:id="@+id/viewpager2"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
2>.recycleview_item.xml适配器布局
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">
//原生控件
<androidx.appcompat.widget.AppCompatTextView
android:id="@+id/tvTitle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:textColor="@android:color/white"
android:textSize="32sp"
tools:text="item" />
</RelativeLayout>
3.ViewPage2的适配器
package com.wd.viewpage2demo;
import android.content.Context;
import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.RelativeLayout;
import android.widget.TextView;
import java.util.List;
import androidx.viewpager2.widget.ViewPager2;
/**
* Author : 张自力
* Created on time.
*
* ViewPage2的适配器
*
*/
public class ViewPagerAdapter extends RecyclerView.Adapter<ViewPagerAdapter.ViewHolder> {
private List<String> mData;
private LayoutInflater mInflater;
private ViewPager2 viewPager2;
//定义一个色彩背景数组
private int[] colorArray = new int[]{android.R.color.black, android.R.color.holo_blue_dark,
android.R.color.holo_green_dark, android.R.color.holo_red_dark};
public ViewPagerAdapter(Context context, List<String> data, ViewPager2 viewPager2) {
this.mInflater = LayoutInflater.from(context);
this.mData = data;
this.viewPager2 = viewPager2;
}
@NonNull
@Override
public ViewPagerAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
View view = mInflater.inflate(R.layout.recycleview_item, parent, false);
return new ViewHolder(view);
}
@Override
public void onBindViewHolder(@NonNull ViewPagerAdapter.ViewHolder holder, int position) {
String animal = mData.get(position);
holder.myTextView.setText(animal);
holder.relativeLayout.setBackgroundResource(colorArray[position]);
}
@Override
public int getItemCount() {
return mData.size();
}
public static class ViewHolder extends RecyclerView.ViewHolder {
TextView myTextView;
RelativeLayout relativeLayout;
ViewHolder(View itemView) {
super(itemView);
myTextView = itemView.findViewById(R.id.tvTitle);
relativeLayout = itemView.findViewById(R.id.container);
}
}
}
4.Activity界面编写
package com.wd.viewpage2demo;
import android.os.Bundle;
import androidx.appcompat.app.AppCompatActivity;
import java.util.ArrayList;
import java.util.List;
import androidx.viewpager2.widget.ViewPager2;
public class MainActivity extends AppCompatActivity {
private ViewPager2 viewpager2;
private List<String> list;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//初始化控件
initView();
//初始化数据
initDatas();
//ViewPage2设置
setViewPage2S();
}
/**
* ViewPage2设置
*
* */
private void setViewPage2S() {
/**
* 垂直方向属性
* 默认是水平方向ORIENTATION_HORIZONTAL,垂直是ORIENTATION_VERTICAL
*
* */
//设置方向
viewpager2.setOrientation(ViewPager2.ORIENTATION_VERTICAL);
//设置adapter
viewpager2.setAdapter(new ViewPagerAdapter(this, list, viewpager2));
viewpager2.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
@Override
public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
super.onPageScrolled(position, positionOffset, positionOffsetPixels);
}
@Override
public void onPageSelected(int position) {
super.onPageSelected(position);
}
@Override
public void onPageScrollStateChanged(int state) {
super.onPageScrollStateChanged(state);
}
});
}
/**
* 初始化数据
*
* */
private void initDatas() {
list = new ArrayList<>();
list.add("页面一");
list.add("页面二");
list.add("页面三");
list.add("页面四");
}
/**
* 初始化控件
*
* */
private void initView() {
//初始化ViewPage2
viewpager2 = (ViewPager2) findViewById(R.id.viewpager2);
}
}
三.RecyclerView和ViewPage2结合使用出现的坑点及解决方案：
1.将build tools更新到3.2.0，gradle更新到4.6，依赖库统一更新到28.0.0，这一步非常重要，否则会导致第二步不能完全转换成功（如果已经更新过了，可以忽略这一步）
2.选择工程右键→Refactor→Migrate to Androidx：
https://img-blog.csdnimg.cn/20190311164212477.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjc5NzA0OA==,size_16,color_FFFFFF,t_70
3.选中所有需要重命名的目录，执行Do Refactor：
https://img-blog.csdnimg.cn/2019031116422580.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mjc5NzA0OA==,size_16,color_FFFFFF,t_70
