在 onItemClick()方法中定义的Toast没有反应，LogCat里面也?报错

package com.example.listviewactivity;


import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;


public class MainActivity extends Activity implements OnItemClickListener  {


private ArrayAdapter<Data> adapter;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

ListView lv = (ListView)findViewById(R.id.listView1);//获取界面上的listView
adapter = new ArrayAdapter<Data>(this,android.R.layout.simple_list_item_1);//定义适配器
//利用系统默认资源（列表项样式）
adapter.add(new Data("这个","女",11));
adapter.add(new Data("漂亮","男",11));
lv.setAdapter(adapter);//用适配器给listView添加数据项
lv.setOnItemClickListener(this);
}


@Override
public 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;
}


@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
// TODO 自动生成的方法存根
Data data = adapter.getItem(arg2);
Toast.makeText(MainActivity.this, String.format("名字：%s, 性别：%s, 年龄：%d", data.getUsername(),data.getSex(),data.getAge()),Toast.LENGTH_SHORT);


}


}