Android Realizes the Infinite Loop Effect of ViewPager (II)

In this paper, we share the second way of Android to realize ViewPager infinite loop effect for your reference. The specific contents are as follows

Principle: Set getCount to infinity in Adapter

package com.xiaomai.myproject.demo;

import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.LinearLayout;

import com.xiaomai.myproject.R;
import com.xiaomai.myproject.adapter.LoopViewPagerAdapter2;
import com.xiaomai.myproject.base.BaseActivity;

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

/**
 * Created by XiaoMai on 2016/10/9 17:44.
 * 
 */
public class LoopViewPagerDemo2Activity extends BaseActivity {

  /**
   *  When to update the picture 
   */
  private static final int UPDATE_TIME = 3 * 1000;

  private ViewPager mViewPager;

  private LoopViewPagerAdapter2 mAdapter;

  /**
   *  Indicate Point
   */
  private LinearLayout mLinearLayoutPonits;

  /**
   *  Picture resource collection 
   */
  private int[] mImageIds;

  /**
   *  Picture collection 
   */
  private List<ImageView> mImageList;

  /**
   *  Of the current advertisement index
   */
  private int mCurrentPageIndex;

  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

  }

  @Override
  protected void initVariables() {
    super.initVariables();
    /**
     *  Initialize the resources of the picture id
     */
    mImageIds = new int[]{
        R.mipmap.ic_launcher,
        R.mipmap.ic_launcher,
        R.mipmap.ic_launcher,
        R.mipmap.ic_launcher,
        R.drawable.my_toast,
        R.drawable.my_toast,
        R.drawable.my_toast,
        R.drawable.my_toast};
    /**
     *  Add ImageView
     */
    mImageList = new ArrayList<>();
    // Add two extra pictures 
    ViewGroup.LayoutParams layoutParams =
        new ViewGroup.LayoutParams(
            ViewGroup.LayoutParams.MATCH_PARENT,
            ViewGroup.LayoutParams.WRAP_CONTENT);
    for (int i = 0; i < mImageIds.length; i++) {
      ImageView imageView = new ImageView(mContext);
      imageView.setLayoutParams(layoutParams);
      mImageList.add(imageView);
    }
  }

  @Override
  protected void initViews() {
    mLinearLayoutPonits = (LinearLayout) findViewById(R.id.activity_ll_container);
    mViewPager = (ViewPager) findViewById(R.id.activity_loop_viewpager);
    mAdapter = new LoopViewPagerAdapter2(mImageList, mImageIds);
    mViewPager.setAdapter(mAdapter);
    int middle = mAdapter.getCount() / 2;
    mViewPager.setCurrentItem(middle - middle % mImageList.size());
  }

  @Override
  protected int getContentLayout() {
    return R.layout.act_loopviewpager;
  }
}

Code:

package com.xiaomai.myproject.adapter;

import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

import java.util.List;

/**
 * Created by XiaoMai on 2016/10/9 17:53.
 */
public class LoopViewPagerAdapter2 extends PagerAdapter {

  private List<ImageView> mImageList;

  private int[] mImageIds;

  public LoopViewPagerAdapter2(List<ImageView> mImageList, int[] mImageIds) {
    this.mImageList = mImageList;
    this.mImageIds = mImageIds;
  }

  @Override
  public int getCount() {
    return Integer.MAX_VALUE;
  }

  @Override
  public boolean isViewFromObject(View view, Object object) {
    return view == object;
  }

  @Override
  public Object instantiateItem(ViewGroup container, int position) {
    ImageView imageView = mImageList.get(position % mImageList.size());
    imageView.setImageResource(mImageIds[position % mImageIds.length]);
    container.addView(imageView);
    return mImageList.get(position % mImageList.size());
  }

  @Override
  public void destroyItem(ViewGroup container, int position, Object object) {
    container.removeView(mImageList.get(position % mImageList.size()));
  }
}

act_loopviewpager.xml

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

  <include
    android:id="@+id/titleBar"
    layout="@layout/my_app_bar" />

  <android.support.v4.view.ViewPager
    android:id="@+id/activity_loop_viewpager"
    android:layout_width="match_parent"
    android:layout_height="200dp"
    android:layout_below="@id/titleBar" />

  <LinearLayout
    android:id="@+id/activity_ll_container"
    android:layout_width="match_parent"
    android:orientation="horizontal"
    android:gravity="center"
    android:background="@color/toast"
    android:layout_alignBottom="@id/activity_loop_viewpager"
    android:visibility="gone"
    android:layout_height="40dp"/>
</RelativeLayout>