错误提示空指针异常,本人看了好几遍没找到,望大神们指点
public class MainActivity extends Activity {
List list=new ArrayList();
ListView lv=null;
EditText et=null;
Button btn=null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
list.add(new Person("张三","男",22));
list.add(new Person("李四","男",22));
lv=(ListView) findViewById(R.id.lv);
et=(EditText) findViewById(R.id.et);
btn=(Button) findViewById(R.id.btn);
lv.setAdapter(new MyAdapter());
}
class MyAdapter extends BaseAdapter{
@Override
public int getCount() {
// TODO Auto-generated method stub
return list.size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return null;
}
@Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
View v=convertView;
MyWrapper wrapper=null;
if(v==null){
v=LayoutInflater.from(MainActivity.this).inflate(R.layout.linearlayout, null);
wrapper=new MyWrapper(v);
v.setTag(wrapper);
}
else{
wrapper=(MyWrapper) v.getTag();
}
TextView tvname=wrapper.getTvname();
TextView tvsex=wrapper.getTvsex();
TextView tvage=wrapper.getTvage();
tvname.setText(list.get(position).getName());
tvsex.setText(list.get(position).getSex());
tvage.setText(list.get(position).getAge()+"");
return v;
}
}
class MyWrapper{
TextView tvname=null;
TextView tvsex=null;
TextView tvage=null;
View v=null;
public MyWrapper(View v) {
super();
this.v = v;
}
public TextView getTvname(){
if(tvname==null){
tvname=(TextView) v.findViewById(R.id.tvname);
}
return tvname;
}
public TextView getTvsex(){
if(tvsex==null){
tvname=(TextView) v.findViewById(R.id.tvsex);
}
return tvsex;
}
public TextView getTvage(){
if(tvage==null){
tvage=(TextView) v.findViewById(R.id.tvage);
}
return tvage;
}
}
}