Android实现ViewPager无限循环效果（二）

本文实例为大家分享了Android实现ViewPager无限循环效果的第二种方式，供大家参考，具体内容如下

原理：在Adapter中将getCount设置为无限大

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 {

  /**
   * 更新图片的时间
   */
  private static final int UPDATE_TIME = 3 * 1000;

  private ViewPager mViewPager;

  private LoopViewPagerAdapter2 mAdapter;

  /**
   * 指示Point
   */
  private LinearLayout mLinearLayoutPonits;

  /**
   * 图片资源集合
   */
  private int[] mImageIds;

  /**
   * 图片集合
   */
  private List<ImageView> mImageList;

  /**
   * 当前广告的index
   */
  private int mCurrentPageIndex;

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

  }

  @Override
  protected void initVariables() {
    super.initVariables();
    /**
     * 初始化图片的资源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};
    /**
     * 添加ImageView
     */
    mImageList = new ArrayList<>();
    //额外添加两张图片
    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;
  }
}

代码：

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>

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