学习Android——ListView之adapter

package com.example.demo1;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import android.app.Activity;import android.os.Bundle;import android.util.Log;import android.view.Gravity;import android.view.View;import android.widget.AbsListView;import android.widget.AbsListView.OnScrollListener;import android.widget.AdapterView;import android.widget.AdapterView.OnItemClickListener;import android.widget.ArrayAdapter;import android.widget.ListView;import android.widget.SimpleAdapter;import android.widget.Toast;public class MainActivity extends Activity implements OnItemClickListener,        OnScrollListener {    private ListView listview;    private SimpleAdapter simp_adapter;    private ArrayAdapter<String> arr_adapter;    private String[] res = { "苹果", "香蕉", "西瓜" };    private List<Map<String, Object>> dataList;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.demo);        // 初始化控件        listview = (ListView) findViewById(R.id.listView);        // 新建适配器,并导入数据源        arr_adapter = new ArrayAdapter<String>(this,                android.R.layout.simple_list_item_1, res);        /*SimpleAdapter的参数         *  1.content:上下文          *  2.date:------|数据源List<? extendsMap<String, ?>> data 一个Map组成的list集合          *         ------|每一个Map都会去对应ListView列表中的一行         *         ------|每一个Map(键—值对)中的键必须包含多欧在from中所指的键          *  3.resource:列表项的布局文件ID         *  4.from:Map中的键名          *  5.to:绑定数据视图中的ID,与from对应         */        dataList = new ArrayList<Map<String, Object>>();*// 注意不要忘了*        String[] from = { "img", "text" };        int[] to = { R.id.img, R.id.text };        simp_adapter = new SimpleAdapter(this, getData(), R.layout.item, from,                to);        // 视图加载        // listview.setAdapter(arr_adapter);        listview.setAdapter(simp_adapter);        listview.setOnItemClickListener(this);        listview.setOnScrollListener(this);    }    private List<Map<String, Object>> getData() {        for (int i = 0; i < 20; i++) {            Map<String, Object> map = new HashMap<String, Object>();            map.put("img", R.drawable.spooky);            map.put("text", "iPhone" + i);            dataList.add(map);        }        return dataList;    }    @Override    public void onScrollStateChanged(AbsListView view, int scrollState) {        switch (scrollState) {        case SCROLL_STATE_FLING:            Log.i("tag", "手指不动了，但是屏幕还在滚动状态");            Map<String, Object> map = new HashMap<String, Object>();            map.put("img", R.drawable.ic_launcher);            map.put("text", "新增项");            dataList.add(map);            simp_adapter.notifyDataSetChanged();// 刷新界面，增加数据源            break;        case SCROLL_STATE_TOUCH_SCROLL:            Log.i("tag", "手指滚动状态");            break;        case SCROLL_STATE_IDLE:            Log.i("tag", "静止状态");            break;        default:            break;        }    }    @Override    public void onScroll(AbsListView view, int firstVisibleItem,            int visibleItemCount, int totalItemCount) {    }    @Override    public void onItemClick(AdapterView<?> parent, View view, int position, long id) {        // 获取列表项位置信息        String text = listview.getItemAtPosition(position) + "";// int转为String，会产生两个String对象        // 显示位置信息        Toast toast = Toast.makeText(this, "text=" + text, Toast.LENGTH_SHORT);        toast.setGravity(Gravity.CENTER, 0, 0);        toast.show();    }}