Loop Viewpager

原理：把viewpager的最后一个view加到第一个位置，在最后一个位置再加一个第一个元素。

代码：https://github.com/wds609/loopviewpager/blob/master/app/src/main/java/com/wds/loopviewpager/LoopViewPager.java

package com.wds.loopviewpager;

import android.content.Context;

import android.support.v4.view.PagerAdapter;

import android.support.v4.view.ViewPager;

import android.util.AttributeSet;

import android.view.View;

import java.util.ArrayList;

public class LoopViewPager extends ViewPager {

public LoopViewPager(Context context) {

super(context);

}

public LoopViewPager(Context context, AttributeSet attrs) {

super(context, attrs);

}

@Override

public void setAdapter(PagerAdapter adapter) {

super.setAdapter(adapter);

addOnPageChangeListener(new LoopOnPageChangeListener(this));

setCurrentItem(1);

setOffscreenPageLimit(adapter.getCount());

}

public static class LoopOnPageChangeListener implements OnPageChangeListener {

private LoopViewPager mLoopViewPager;

private int mFinalPosition;

public LoopOnPageChangeListener(LoopViewPager loopViewPager) {

this.mLoopViewPager = loopViewPager;

}

@Override

public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

mFinalPosition = position;

}

@Override

public void onPageSelected(int position) {

}

@Override

public void onPageScrollStateChanged(int state) {

if (state == ViewPager.SCROLL_STATE_IDLE) {

PagerAdapter adapter = mLoopViewPager.getAdapter();

if (mFinalPosition == 0) {

mLoopViewPager.setCurrentItem(adapter.getCount() - 2, false);

}

if (mFinalPosition == adapter.getCount() - 1) {

mLoopViewPager.setCurrentItem(1, false);

}

}

}

}

public static abstract class LoopViewPagerAdapter extends PagerAdapter {

protected ArrayList mDatas = new ArrayList<>();

public LoopViewPagerAdapter(ArrayList datas) {

if (datas != null && datas.size() != 0) {

mDatas.add(datas.get(datas.size() - 1));

mDatas.addAll(datas);

mDatas.add(datas.get(0));

}

}

@Override

public final int getCount() {

return mDatas.size();

}

@Override

public boolean isViewFromObject(View view, Object object) {

return view == object;

}

}

}