ViewPager的IllegalStateException运行异常处理

来源：互联网发布：智能电视软件市场编辑：程序博客网时间：2024/05/22 08:20

开发场景：1.在activity执行oncreate()生命周期时，初始化viewpager控件、viewpager的适配器adapter，adapter的填充数组list；

2. 当用户刷新数据的时候，先清空listview，并将新数据填充到list中，调用adapter的notifyDataSetChanged()方法，此时产生运行错误。

错误类型： Caused by: java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.

代码如下：

MainActivity.java

package com.example.androidtest;import java.util.ArrayList;import java.util.List;import android.app.Activity;import android.os.Bundle;import android.support.v4.view.ViewPager;import android.view.LayoutInflater;import android.view.View;import android.widget.ImageView;public class MainActivity extends Activity {private ViewPager vp ;private VPAdapter vpAdapter;private List<View> views;@Override  public void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  vp = (ViewPager)findViewById(R.id.vp);views = new ArrayList<View>();vpAdapter = new VPAdapter(views);vp.setAdapter(vpAdapter);}public void doClick(View v){switch (v.getId()) {case R.id.add:views.clear();for (int i = 0; i < 3; i++) {ImageView iv = (ImageView)((View)LayoutInflater.from(this).inflate(R.layout.imageview, null)).findViewById(R.id.iv);iv.setImageResource(R.drawable.ic_launcher);views.add(iv);}vpAdapter.notifyDataSetChanged();break;case R.id.del:break;}}}

package com.example.androidtest;import java.util.ArrayList;import java.util.List;import android.support.v4.view.PagerAdapter;import android.view.View;import android.view.ViewGroup;public class VPAdapter extends PagerAdapter {private List<View> viewList;public VPAdapter(List<View> viewList){if(viewList!=null){this.viewList = viewList;}else{this.viewList = new ArrayList<View>();}}@Overridepublic int getCount() {// TODO Auto-generated method stubreturn viewList.size();}@Overridepublic boolean isViewFromObject(View arg0, Object arg1) {// TODO Auto-generated method stubreturn arg0==arg1;}@Overridepublic void destroyItem(ViewGroup container, int position, Object object) {container.removeView(viewList.get(position));}@Overridepublic Object instantiateItem(ViewGroup container, int position){//这里的判断是关键代码，首先我们要判断这个view的父容器是否为null；//如果为null，证明是第一次加入，直接添加即可，//如果不为null。此时需要先remove掉父容器，再将这个view添加到container中，否则就会产生IllegalStateException异常if(viewList.get(position).getParent()==null){container.addView(viewList.get(position), 0);}else{((ViewGroup)viewList.get(position).getParent()).removeView(viewList.get(position));container.addView(viewList.get(position));}return viewList.get(position);}}

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