安卓控件和持有者模式，出现空指针异常

Question

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;
    }
}

}

Answer 1

就不能把log截出来吗，？