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;
}
}
}
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