关于viewpager的滑动问题

今天碰到很诡异的问题,viewpager中放置至少三张图片的时候能够正常实现循环滑动,只放置一张或者两张的时候就不行。

后来发现问题症结:viewpager需要保证既可以向左滑动,又可以向右滑动,因此当前显示view的左侧和右侧都是存在的,只有超过这三个范围之外的才对其调用destory方法。

循环实现的代码如下:

package com.wot.cloudsensing.carrotfarm.adapter;



import java.util.ArrayList;



import com.wot.cloudsensing.carrotfarm.R;



import android.content.Context;

import android.support.v4.view.PagerAdapter;

import android.support.v4.view.ViewPager;

import android.view.View;

import android.view.ViewGroup;

import android.widget.ImageView;

import android.widget.LinearLayout.LayoutParams;



public class ViewPagerAdapter extends PagerAdapter {

    private ArrayList<ImageView> imageviews;

    private int size = 0;



    public ViewPagerAdapter(ArrayList<ImageView> views) {

        this.imageviews = views;

        this.size = views.size();



    }



    @Override

    public int getCount() {

        return Integer.MAX_VALUE;

    }



    @Override

    public boolean isViewFromObject(View arg0, Object arg1) {

        return arg0 == arg1;

    }



    @Override

    public void destroyItem(ViewGroup container, int position, Object object) {

        System.out.println("111  destroyItem position = "

                + (position % imageviews.size()));

        ((ViewPager) container).removeView(imageviews.get(position

                % imageviews.size()));

    }



    @Override

    public Object instantiateItem(ViewGroup container, int position) {

        System.out.println("111  instantiateItem instantiateItem  position = "

                + (position % imageviews.size()));

        ((ViewPager) container).addView(

                imageviews.get(position % imageviews.size()), 0);

        return imageviews.get(position % imageviews.size());

    }



}

 

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