Viewpager2—登录注册引导页面

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介绍

屏幕滑动是两个完整屏幕之间的切换，在设置向导或幻灯片等界面中很常见

实现图(图片来源于网络):

例子

1、创建视图
我这里只创建了3个XML

fragment0.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:id="@+id/content"android:layout_width="match_parent"android:layout_height="match_parent" ><ImageViewandroid:layout_width="match_parent"android:layout_height="match_parent"android:adjustViewBounds="true"android:scaleType="fitXY"android:src="@drawable/p0"/></LinearLayout>

fragment1.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:id="@+id/content"android:layout_width="match_parent"android:layout_height="match_parent" ><ImageViewandroid:layout_width="match_parent"android:layout_height="match_parent"android:adjustViewBounds="true"android:scaleType="fitXY"android:src="@drawable/p1"/></LinearLayout>

fragment2.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:id="@+id/content"android:layout_width="match_parent"android:layout_height="match_parent" ><ImageViewandroid:layout_width="match_parent"android:layout_height="match_parent"android:adjustViewBounds="true"android:scaleType="fitXY"android:src="@drawable/p2"/></LinearLayout>

2、创建 Fragment
根据构造方法传进来的 int i；返回不同的视图(i是等下用到的FragmentStateAdapter适配器中传进去的)

package com.example.xianyu;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;public class mFragment extends Fragment {
    int i = 0;mFragment(int i){
    this.i = i;}@Nullable@Overridepublic View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = null;switch (i){
    case 0: {
    view = inflater.inflate(R.layout.fragment0, container, false);break;}case 1: {
    view =  inflater.inflate(R.layout.frament1, container, false);break;}case 2: {
    view = inflater.inflate(R.layout.fragment2, container, false);break;}}return view;}
}

3、主Activity，并创建自定义适配器继承自FragmentStateAdapter

activity_screen_slide.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- activity_screen_slide.xml -->
<androidx.viewpager2.widget.ViewPager2xmlns:android="http://schemas.android.com/apk/res/android"android:id="@+id/pager"android:layout_width="match_parent"android:layout_height="match_parent" />

homeActivity

package com.example.xianyu;import android.os.Bundle;import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentActivity;
import androidx.viewpager2.adapter.FragmentStateAdapter;
import androidx.viewpager2.widget.ViewPager2;public class homeActivity extends FragmentActivity {
    //要显示的页数private static final int NUM_PAGES = 3;private ViewPager2 viewPager2;// 适配器，为ViewPager2提供页面 private FragmentStateAdapter pagerAdapter;@Overrideprotected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);setContentView(R.layout.activity_screen_slide);viewPager2 = findViewById(R.id.pager);pagerAdapter = new ScreenSlidePagerAdapter(this);viewPager2.setAdapter(pagerAdapter);}@Overridepublic void onBackPressed() {
    if (viewPager2.getCurrentItem() == 0) {
                super.onBackPressed();} else {
               viewPager2.setCurrentItem(viewPager2.getCurrentItem() - 1);}}//自定义的类，继承自FragmentStateAdapter适配器private class ScreenSlidePagerAdapter extends FragmentStateAdapter {
    public ScreenSlidePagerAdapter(FragmentActivity fa) {
    super(fa);}
//主要是createFragment这个方法@Overridepublic Fragment createFragment(int position) {
    return new mFragment(position);}@Overridepublic int getItemCount() {
    return NUM_PAGES;}}
}

总结

非常实用，快快收藏叭！