Spinner添加/删除数据，求科普

[kitencx]

废话不多说，上代码
MainActivity.java

package com.example.dropdownlisttest;

import java.util.ArrayList;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.AlertDialog.Builder;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.EditText;
import android.widget.Spinner;

public class MainActivity extends Activity {
	private Spinner mSpinner ;
	private ArrayList<String> cities;
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		 mSpinner = (Spinner)findViewById(R.id.spinner);
		
		initSpinner();
	}

	@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;
	}
	
	private void initSpinner(){
		
		cities  = new ArrayList<String>();
		cities.add("北京");
		cities.add("上海");
		cities.add("南京");
		cities.add("杭州");
		cities.add("广州");
		cities.add("添加...");
		
		mSpinner.setOnItemSelectedListener(new OnItemSelectedListener() {
			@Override
			public void onItemSelected(AdapterView<?> parent, View view,
					int position, long id) {
				// TODO Auto-generated method stub
				if(position == cities.size() - 1){
					AlertDialog.Builder builder = new Builder(MainActivity.this);
					builder.setTitle("添加城市");
					final EditText city = new EditText(MainActivity.this);
					builder.setView(city);
					builder.setNegativeButton("添加", new OnClickListener() {
						
						@Override
						public void onClick(DialogInterface dialog, int which) {
							// TODO Auto-generated method stub
							cities.add(cities.size()-1, city.getText().toString());
							dialog.dismiss();
						}
					});
					builder.show();
				}
			}
			
			@Override
			public void onNothingSelected(AdapterView<?> parent) {
				// TODO Auto-generated method stub
			}
		});
		
		CustomizedAdapter adapter = new CustomizedAdapter(this, R.layout.dropdown_item, cities);
		mSpinner.setAdapter(adapter);
	}

}

CustomizedAdapter.java

package com.example.dropdownlisttest;

import java.util.List;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.Spinner;
import android.widget.TextView;

public class CustomizedAdapter extends BaseAdapter {
	private Context context;
	private List<String> mList;
	private LayoutInflater inflater;
	
	public CustomizedAdapter(){}
	
	public CustomizedAdapter(Context context, int layout, List<String> list){
		this.context = context;
		inflater = LayoutInflater.from(context);
		this.mList = list;
	}
	
	@Override
	public int getCount() {
		// TODO Auto-generated method stub
		return mList.size();
	}

	@Override
	public Object getItem(int position) {
		// TODO Auto-generated method stub
		return mList.get(position);
	}

	@Override
	public long getItemId(int position) {
		// TODO Auto-generated method stub
		return position;
	}

	@Override
	public View getView(final int position, View convertView, ViewGroup parent) {
		// TODO Auto-generated method stub
		if(null == convertView){
			convertView = inflater.inflate(R.layout.dropdown_item, null);
		}
		TextView textView = (TextView)convertView.findViewById(R.id.textview1);
		Button delButton = (Button)convertView.findViewById(R.id.delete);
		textView.setText(mList.get(position));
		
		if(position == mList.size() - 1){
			//最后一项不允许删除
			delButton.setOnClickListener(null);
			delButton.setVisibility(View.INVISIBLE);
		}else{
			delButton.setOnClickListener(new OnClickListener() {
				@Override
				public void onClick(View v) {
					// TODO Auto-generated method stub
					mList.remove(position);
					notifyDataSetChanged();
				}
			});
		}
		
		return convertView;
	}

}

代码如上，结果碰上了令我几个问题一直搞不明白
1.Spinner的下拉列表中，在Button上注册了onClickListener之后，发现Item居然不可选了，就是只能点击按钮删除，而点别的地方一点反应都没有，最后一个Item我移除了onClickListener之后，它就是可选的，是否Spinner只能响应一个事件？
2.当我连续删除Item的时候，会莫名其妙的触发添加事件，即莫名其妙的系统会选中最后一项，一直搞不明白为什么。
3.在getView()中，我判断的是position == mList.size()-1，即最后一项，我不显示删除按钮，但是实际运行时，连第一项也没有删除按钮

几个问题我百思不解，求大神科普下。

[kitencx]

上张图，直观点

[kitencx]

结贴，自己搞定了。。