Android开发报错系列(一),java.lang.NullPointerException,at android.widget.ListView.setupChild,appwidgetlistview
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Android开发报错系列(一),java.lang.NullPointerException,at android.widget.ListView.setupChild,appwidgetlistview
问题描述:运行代码是报空指针错误,java.lang.NullPointerException,at Android.widget.ListView.setupChild
问题定位:listview控件报错,查找原因并没有问题,怀疑adapter设置item值时出错,检查代码,果然是这里报错
在设置完adapter的item值得时候,由于粗心,return convertView 时第一次返回成了 return null,导致了上述错误
1 public class CasesAdapter extends NormalListAdapter<Cases>{ 2 private ViewHolder viewHolder = null; 3 private Context mCtc; 4 private static class ViewHolder { 5 public ImageView aImg; 6 public TextView aTitle; 7 public TextView aHits; 8 public TextView aTime; 9 } 10 public CasesAdapter(Context context, List<Cases> item) { 11 super(context, item); 12 // TODO Auto-generated constructor stub 13 mCtc = context; 14 } 15 16 @Override 17 public View getView(int position, View convertView, ViewGroup parent) { 18 //判断试图是否为空 19 if (convertView==null) { 20 //如果试图为空的情况下,加载试图页面 21 convertView=inflater.inflate(R.layout.list_item_cases, null); 22 // 实例化 ViewHolder 23 viewHolder = new ViewHolder(); 24 // 设置viewholder中元素对应的控件 25 viewHolder.aImg=(ImageView) convertView.findViewById(R.id.imgs); 26 viewHolder.aTitle=(TextView) convertView.findViewById(R.id.msg_title); 27 viewHolder.aHits=(TextView) convertView.findViewById(R.id.msg_hit); 28 viewHolder.aTime=(TextView) convertView.findViewById(R.id.msg_time); 29 convertView.setTag(viewHolder); 30 } 31 else { 32 viewHolder=(ViewHolder) convertView.getTag(); 33 } 34 Cases cs=itemContent.get(position); 35 //设置控件绑定的数值 36 viewHolder.aTitle.setText(cs.getTitle()); 37 viewHolder.aHits.setText(cs.getHits()); 38 viewHolder.aTime.setText(cs.getAddtime()); 39 // 网络异步加载 40 ImageLoader.getInstance().displayImage("http://192.168.2.26:8012"+cs.getFilename(), 41 viewHolder.aImg, Define.options1, 42 new AnimateFirstDisplayListener()); 43 return null;//该处报错,引起异常 44 } 45 46 }
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