getCount和getView方法怎么多次被调用

运行如下:

点击按钮，情况是这样的


执行gridView.setAdapter(adapter);时会去调用getCount()方法，但后面getCount和getView方法怎么多次被调用，什么情况下调用的？不是说有9张图就只调用9次getView方法么？
然后任意点击9张图的其中一张，LogCat如下:

咦？怎么getItem方法没被调用到？
还有data.getIntExtra("imageId",R.drawable.abc_ab_bottom_solid_dark_holo )
怎么不能这样写data.getIntExtra("imageId")？不是说键值存储，得到键，就得到了值么？
代码在下面的回答

你把gridview的宽高设为定值，或者设置为match_parent 试一下

然后任意点击9张图的其中一张，LogCat如下:

MainActivity.java

 package com.example.gridviewdemo;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;

public class MainActivity extends Activity implements OnClickListener {
    private Button button01;
    private ImageView view;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button01=(Button)findViewById(R.id.bt1);
        view=(ImageView)findViewById(R.id.iv1);
        button01.setOnClickListener(this);
    }

    @Override
    public void onClick(View v)
    {
        switch(v.getId())
        {
        case R.id.bt1:
            Intent intent=new Intent(MainActivity.this,ResultActivity.class);
            MainActivity.this.startActivityForResult(intent,1);
        }
    }

    protected void onActivityResult(int requestCode,int resultCode,Intent data)
    {
        if (requestCode==1&&resultCode==Activity.RESULT_OK)
        {
            int imageId=data.getIntExtra("imageId",R.drawable.abc_ab_bottom_solid_dark_holo);
            view.setImageResource(imageId);
        }
    }

    @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 boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

ResultActivity.java

 package com.example.gridviewdemo;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
import android.widget.TextView;

public class ResultActivity extends Activity
{
    private GridView gridView;
    private int[] images={R.drawable.abc_ic_clear,R.drawable.abc_textfield_search_selected_holo_light,R.drawable.abc_tab_selected_pressed_holo,
            R.drawable.abc_menu_hardkey_panel_holo_light,R.drawable.abc_spinner_ab_holo_dark,R.drawable.abc_list_selector_holo_light,
            R.drawable.abc_menu_dropdown_panel_holo_dark,R.drawable.abc_textfield_search_selected_holo_light,R.drawable.abc_ab_solid_dark_holo
            };
    private List<Map<String,Object>> list;
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_result);
        gridView=(GridView)findViewById(R.id.gv1);
    list=getResource();
    MyBaseAdapter adapter=new MyBaseAdapter();
    gridView.setAdapter(adapter);
    gridView.setOnItemClickListener (new OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent,View view,int position,long id)
        {
            Intent intent=new Intent();
            intent.putExtra("imageId",images[position]);
            setResult(Activity.RESULT_OK,intent);
            ResultActivity.this.finish();
        }
    });
    }

    public class MyBaseAdapter extends BaseAdapter 
    {
        @Override
        public int getCount()
        {
            Log.e("ResultActivity","getCount");
            return list.size();
        }
        @Override
        public Object getItem(int position)
        {
            Log.e("ResultActivity","getItem");
            return list.get(position);
        }
        @Override
        public long getItemId(int position)
        {
            Log.e("ResultActivity","getItemId");
            return position;
        }
        @Override
        public View getView(int position,View convertView,ViewGroup parent)
        {
            ViewHolder viewHolder=null;
            Log.e("ResultActivity","getView");
            if (convertView==null)
            {
                LayoutInflater layoutInflater=LayoutInflater.from(ResultActivity.this );
                convertView=layoutInflater.inflate(R.layout.activity_item,null);
                viewHolder=new ViewHolder();
                viewHolder.imageView=(ImageView)convertView.findViewById(R.id.iv2);
                viewHolder.textView=(TextView)convertView.findViewById(R.id.tv2);
                convertView.setTag(viewHolder);
            }
            else
            {
                viewHolder=(ViewHolder)convertView.getTag();
            }
            viewHolder.imageView.setImageResource((Integer)list.get(position).get("images"));
            viewHolder.textView.setText((CharSequence)list.get(position).get("text"));
            return convertView;
        }
    }
    static class ViewHolder
    {
        ImageView imageView;
        TextView textView;
    }
    public List<Map<String,Object>> getResource()
    {
        List<Map<String,Object>> list=new ArrayList<Map<String,Object>>();
        for (int i=0;i<images.length;i++)
        {
            Map<String,Object> map=new HashMap<String,Object>();
            map.put("images",images[i]);
            map.put("text","图--"+i);
            list.add(map);
        }
        return list;
    }
}