照抄书下代码还报错，请帮看看是哪的有关问题

照抄书上代码还报错，请帮看看是哪的问题？
package com.example.lucky;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.*;
import android.view.*;

public class MainActivity extends Activity {

  @Override
  public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.activity_main);
   
  Spinner sp1=(Spinner)findViewById(R.id.spinner1);
   
  final String[] chooseStr={"A","B","C"};
   
  ArrayAdapter<String>adapter=new ArrayAdapter<String>(this,android.R.layout.simple_spinner_item,chooseStr);
   
  adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
   
  sp1.setPrompt("请选择：");
  sp1.setAdapter(adapter);
   
//下面这一句报错：The method setOnItemSelectedListener(AdapterView.OnItemSelectedListener) in the type //AdapterView<SpinnerAdapter> is not applicable for the arguments (new OnItemSelectedListener(){})
  sp1.setOnItemSelectedListener(new OnItemSelectedListener()
  {
  @Override
  public void OnItemSelected(AdapterView<?> arg0,View arg1, int arg2, long arg3)
  {
 
  }
  });
  }

  @Override
  public boolean onCreateOptionsMenu(Menu menu) {
  getMenuInflater().inflate(R.menu.activity_main, menu);
  return true;
  }
}


------解决方案--------------------
在文件前面加几个import试试，如下：
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
------解决方案--------------------
你会不会点红叉，修复错误？
------解决方案--------------------
点红叉自动修复错误，不知道的查，还有快捷方式ctrl+f1,自己看看是哪里的问题