GridView组件

package cn.bzu.ui;

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

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.GridView;
import android.widget.ImageView;
import android.widget.SimpleAdapter;

public class MainActivity extends Activity {
 private GridView smallImageGrid;
 private ImageView showImage;
 private int[] pics;//存放图片id的数组

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        //查找组件
        smallImageGrid=(GridView) this.findViewById(R.id.imagelist);
        showImage=(ImageView) this.findViewById(R.id.imageshow);
        //第一步 实例化图片ID的数组
        pics=new int[]{R.drawable.a,R.drawable.b,R.drawable.c,R.drawable.d,R.drawable.e,R.drawable.f};
        //第二步 创建一个List<Map>集合，用于将图片ID转换为List集合
        List<Map<String,Object>> pic_items=new ArrayList<Map<String,Object>>();
        for(int pic_id:pics){
          Map<String, Object> item=new HashMap<String, Object>();
          item.put("pic", pic_id);
          pic_items.add(item);
        }
        //第三步 创建SimpleAdaper适配器，以备与GridView组件进行绑定
        SimpleAdapter adapter=new SimpleAdapter(this,pic_items,R.layout.grid,new String[]{"pic"},new int[]{R.id.smallImage});
        //第四步  GridView组件与adapter适配器进行绑定
        smallImageGrid.setAdapter(adapter);
        //第五步 为showImage组件设置默认图片
        showImage.setImageResource(pics[0]);
        //第六步 注册事件监听
        smallImageGrid.setOnItemClickListener(new GridViewHandler());
    }
   
   
    public class GridViewHandler implements OnItemClickListener{

     /**
      * AdapterView adpaterview：发生点击事件的AdapterView；
      * View view：AdapterView中被用户点击的Item（GridView中的Item）；
      * int positon：被点击的Item在Adapter中的位置
      * long id：被点击的Item的Id
      */

  @Override
  public void onItemClick(AdapterView<?> adapter, View view, int position,
    long id) {
   showImage.setImageResource(pics[position]);
  }
     
    }
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
}