23. ViewPager

23. ViewPager

页面滑动效果

23.1 页面布局

layout1.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ff00ffff"
    android:orientation="vertical"
    >

    <TextView
        android:textSize="30sp"
        android:text="layout1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

</LinearLayout>

layout2.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ff00ff00"
    android:orientation="vertical"
    >

    <TextView
        android:textSize="30sp"
        android:text="layout2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

</LinearLayout>

layout3.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffff00"
    android:orientation="vertical"
    >

    <TextView
        android:textSize="30sp"
        android:text="layout3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

</LinearLayout>

23.2 创建ViewPager
activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    >
    
    <androidx.viewpager.widget.ViewPager
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/vp"
        />
    
</LinearLayout>

23.3 创建适配器Adapter
package com.dingjiaxiong.myviewpager;

import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.viewpager.widget.PagerAdapter;

import java.util.List;

public class MyAdapter extends PagerAdapter {
    
    //构造方法
    private List<View> mListView;

    public MyAdapter(List<View> mListView) {
        this.mListView = mListView;
    }

    @NonNull
    @Override
    public Object instantiateItem(@NonNull ViewGroup container, int position) { //将给定位置的view添加到viewgroup容器中，并显示出来；返回一个key值，与view一一对应
        container.addView(mListView.get(position),0);
        return mListView.get(position);
    }

    @Override
    public int getCount() { //获得ViewPager中有多少个View
        return mListView.size();
    }

    @Override
    public boolean isViewFromObject(@NonNull View view, @NonNull Object object) { //判断key与view是否相等对应
        return view == object;
    }
    
    //销毁
    @Override
    public void destroyItem(@NonNull ViewGroup container, int position, @NonNull Object object) {
        container.removeView(mListView.get(position));
    }
}

23.4 设置视图数据
MainActivity.java

package com.dingjiaxiong.myviewpager;

import androidx.appcompat.app.AppCompatActivity;
import androidx.viewpager.widget.ViewPager;

import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        LayoutInflater lf = getLayoutInflater().from(this);
        View view1 = lf.inflate(R.layout.layout1, null);
        View view2 = lf.inflate(R.layout.layout2, null);
        View view3 = lf.inflate(R.layout.layout3, null);

        //添加到集合中
        List<View> viewList = new ArrayList<>();
        viewList.add(view1);
        viewList.add(view2);
        viewList.add(view3);

        ViewPager viewPager = findViewById(R.id.vp);

        MyAdapter myAdapter = new MyAdapter(viewList);
        viewPager.setAdapter(myAdapter);

    }
}

运行