Android实现轮播图无限循环效果

本文实例为大家分享了android轮播图无限循环的具体代码，供大家参考，具体内容如下

实现无限循环

在getcount()方法中，返回一个很大的值，integer.max_value

在instantiateitem()方法中，获取当前view的索引时，进行取于操作，传递进来的int position是个非常大的数，对他进行求余数

在destroyitem()方法中，同样

在onpageselected()监听方法中，对传递进来的索引进行取于 

反向的无限循环

调用viewpager对象的setcurrentitem()方法，设置第一次进来时候的当前页，参数：int数字，我们把它定位到integer.max_value的中间，并且保证第一条是当前位置，integer.max_value/2-((integer.max_value/2)%banners.size()) 

目前有个左划空白页的问题没解决

package com.tsh.myviewpager;

import java.util.arraylist;
import java.util.list;

import android.app.activity;
import android.os.bundle;
import android.support.v4.view.pageradapter;
import android.support.v4.view.viewpager;
import android.support.v4.view.viewpager.onpagechangelistener;
import android.view.view;
import android.view.viewgroup;
import android.widget.imageview;
import android.widget.linearlayout;
import android.widget.textview;

public class mainactivity extends activity {
  private viewpager vp_banner;
  private linearlayout ll_points;
  private textview tv_title;
  private list<view> banners;
  private string[] titles=new string[]{
      "新闻标题1",
      "新闻标题2",
      "新闻标题3"
  };
  private list<imageview> points=new arraylist<imageview>();
  @override
  protected void oncreate(bundle savedinstancestate) {
    super.oncreate(savedinstancestate);
    setcontentview(r.layout.activity_main);
    // 初始化
    vp_banner = (viewpager) findviewbyid(r.id.vp_banner);
    ll_points = (linearlayout) findviewbyid(r.id.ll_points);
    tv_title = (textview) findviewbyid(r.id.tv_title);
    
    // banner部分
    banners = new arraylist<>();
    imageview img1 = new imageview(this);
    img1.setimageresource(r.drawable.a);
    banners.add(img1);
    imageview img2 = new imageview(this);
    img2.setimageresource(r.drawable.b);
    banners.add(img2);
    imageview img3 = new imageview(this);
    img3.setimageresource(r.drawable.c);
    banners.add(img3);
    
    //小图标
    ll_points=(linearlayout) findviewbyid(r.id.ll_points);
    for(int i=0;i<banners.size();i++){
      imageview image=new imageview(this);
      image.setimageresource(r.drawable.point_selector);
      linearlayout.layoutparams params=new linearlayout.layoutparams(5, 5);
      params.rightmargin=4;
      image.setlayoutparams(params);
      
      if(i==0){
        image.setenabled(true);
      }else{
        image.setenabled(false);
      }
      points.add(image);
      ll_points.addview(image);
    }
    
    // 设置适配器
    vp_banner.setadapter(new mypageradapter());
    vp_banner.setcurrentitem(integer.max_value/2-((integer.max_value/2)%banners.size()));
    vp_banner.setonpagechangelistener(new onpagechangelistener() {
      @override
      public void onpageselected(int arg0) {
        tv_title.settext(titles[arg0%banners.size()]);
        //小图标处理
        for(imageview point:points){
          point.setenabled(false);
        }
        points.get(arg0%banners.size()).setenabled(true);
      }
      
      @override
      public void onpagescrolled(int arg0, float arg1, int arg2) {
        // todo auto-generated method stub
        
      }
      
      @override
      public void onpagescrollstatechanged(int arg0) {
        // todo auto-generated method stub
        
      }
    });
    
  }

  private class mypageradapter extends pageradapter {
    @override
    public void destroyitem(viewgroup container, int position, object object) {
      system.out.println("销毁："+position);
      container.removeview((view)object);
      object=null;
    }

    @override
    public object instantiateitem(viewgroup container, int position) {
      system.out.println("初始化："+position);
      position=position%banners.size();
      
      //解决右划出错
      if(banners.get(position).getparent()!=null){
        //container.removeview(banners.get(position));
      }else{
        container.addview(banners.get(position));
      }
      
      return banners.get(position);
    }

    @override
    public int getcount() {
      return integer.max_value;
    }

    @override
    public boolean isviewfromobject(view arg0, object arg1) {
      return arg0 == arg1;
    }
  }
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。