ViewPager初识

由于最近的工程里面有用到这个ViewPager 和 listview 关于这个加载 需要明白一点好作为优化，所以学习一下，以下是学习笔记。

不废话贴源代码

package com.example.viewpagertest001;import java.util.ArrayList;import java.util.List;import android.os.Bundle;import android.app.Activity;import android.support.v4.view.PagerAdapter;import android.support.v4.view.ViewPager;import android.support.v4.view.ViewPager.OnPageChangeListener;import android.view.LayoutInflater;import android.view.Menu;import android.view.View;import android.view.View.OnClickListener;import android.view.ViewGroup;import android.widget.Button;import android.widget.Toast;public class MainActivity extends Activity implements OnClickListener{private Button button1,button2,button3;View view1,view2,view3;private List<view> viewList;private ViewPager mViewPager;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);initButtons();initPager();}private void initButtons() {button1 = (Button)findViewById(R.id.button1);button1.setOnClickListener(this);button2 = (Button)findViewById(R.id.button2);button2.setOnClickListener(this);button3 = (Button)findViewById(R.id.button2);button3.setOnClickListener(this);}private void initPager() {mViewPager = (ViewPager)findViewById(R.id.viewPager);LayoutInflater lf = getLayoutInflater().from(this);view1 = lf.inflate(R.layout.black, null);view2 = lf.inflate(R.layout.white, null);view3 = lf.inflate(R.layout.gray, null);viewList = new ArrayList<view>();viewList.add(view1);viewList.add(view2);viewList.add(view3);initAdapter();mViewPager.setOffscreenPageLimit(viewList.size());mViewPager.setOnPageChangeListener(new OnPageChangeListener() {@Overridepublic void onPageSelected(int arg0) {Toast.makeText(getApplicationContext(),"onPageSelected:"+arg0, 0).show();}@Overridepublic void onPageScrolled(int arg0, float arg1, int arg2) {}@Overridepublic void onPageScrollStateChanged(int arg0) {}});mViewPager.setCurrentItem(2);//view2}private void initAdapter() {PagerAdapter pagerAdapter = new PagerAdapter() {@Overridepublic boolean isViewFromObject(View arg0, Object arg1) {// TODO Auto-generated method stubreturn arg0 == arg1;}@Overridepublic int getCount() {// TODO Auto-generated method stubreturn viewList.size();}@Overridepublic void destroyItem(ViewGroup container, int position,Object object) {// TODO Auto-generated method stubcontainer.removeView(viewList.get(position));}@Overridepublic int getItemPosition(Object object) {// TODO Auto-generated method stubreturn super.getItemPosition(object);}@Overridepublic Object instantiateItem(ViewGroup container, int position) {container.addView(viewList.get(position));return viewList.get(position);}};mViewPager.setAdapter(pagerAdapter);}@Overridepublic boolean onCreateOptionsMenu(Menu menu) {// Inflate the menu; this adds items to the action bar if it is present.getMenuInflater().inflate(R.menu.main, menu);return true;}@Overridepublic void onClick(View v) {// TODO Auto-generated method stub}/*04-04 00:42:48.850: E/AndroidRuntime(760): * java.lang.IllegalStateException: The specified child already has a parent. * You must call removeView() on the child's parent first. * * 状况 可以初始化 当滑动界面的时候崩溃 * * 出现这个错误的时候 我也没有思路 还是在 stackoverflow 找到答案 具体还没有分析，有待于分析 * 添加了 mViewPager.setOffscreenPageLimit(viewList.size()); * http://stackoverflow.com/questions/13559353/how-to-solve-for-viewpager-the-specified-child-already-has-a-parent-you-must*/}</view></view>

xml三个xml如下

<?xml version="1.0" encoding="UTF-8"?><linearlayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@android:color/black"></linearlayout>
只是背景色换了，没有其他变化，该代码经过本人验证，没有任何问题。顺便终于结局了在文章中 发布代码格式的代码了。谢谢该篇文章的作者，谢谢！http://blog.csdn.net/qyp1314/article/details/7321384