Viewpager2—登錄注冊引導頁面

Blog如有不對，敬請斧正
喜歡Android的可以關注我，日常更新Android干貨

介紹

螢屏滑動是兩個完整螢屏之間的切換，在設定向導或幻燈片等界面中很常見

實作圖(圖片來源于網路):

例子

1、創建視圖
我這里只創建了3個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" >

    <ImageView
        android: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" >

    <ImageView
        android: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" >

    <ImageView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:adjustViewBounds="true"
        android:scaleType="fitXY"
        android:src="@drawable/p2"
        />
    </LinearLayout>

2、創建 Fragment
根據構造方法傳進來的 int i；回傳不同的視圖(i是等下用到的FragmentStateAdapter配接器中傳進去的)

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
    @Override
    public 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，并創建自定義配接器繼承自FragmentStateAdapter

activity_screen_slide.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- activity_screen_slide.xml -->
<androidx.viewpager2.widget.ViewPager2
    xmlns: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 {
    //要顯示的頁數
    private static final int NUM_PAGES = 3;
    private ViewPager2 viewPager2;
     // 配接器，為ViewPager2提供頁面 
    private FragmentStateAdapter pagerAdapter;
    
    @Override
    protected 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);
    }

    @Override
    public void onBackPressed() {
        if (viewPager2.getCurrentItem() == 0) {            
            super.onBackPressed();
        } else {           
            viewPager2.setCurrentItem(viewPager2.getCurrentItem() - 1);
        }
    }

 //自定義的類，繼承自FragmentStateAdapter配接器
    private class ScreenSlidePagerAdapter extends FragmentStateAdapter {
        public ScreenSlidePagerAdapter(FragmentActivity fa) {
            super(fa);
        }
//主要是createFragment這個方法
        @Override
        public Fragment createFragment(int position) {
            return new mFragment(position);
        }

        @Override
        public int getItemCount() {
            return NUM_PAGES;
        }


    }
}

總結

非常實用，快快收藏叭！