package com.alexchen.listviewoptimize; 
 
import java.util.ArrayList; 
import java.util.List; 
import android.app.Activity; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.view.ViewGroup; 
import android.widget.BaseAdapter; 
import android.widget.ListView; 
import android.widget.TextView; 
 
public class MainActivity extends Activity { 
 
  private ListView lv_demo; 
  private List<String> list; 
 
  @Override 
  protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.activity_main); 
    lv_demo = (ListView) findViewById(R.id.lv_demo); 
    //list为要加载的条目文本的集合，这里总共是100条 
    list = new ArrayList<String>(); 
    for (int i = 0; i < 100; i++) { 
      list.add("条目" + i); 
    } 
 
    lv_demo.setAdapter(new MyAdapter()); 
  } 
 
  private class MyAdapter extends BaseAdapter { 
 
    @Override 
    public int getCount() { 
      return list.size(); 
    } 
 
    @Override 
    public View getView(int position, View convertView, ViewGroup parent) { 
      //listview_item里只有一个textview 
      View view = View.inflate(MainActivity.this, R.layout.listview_item, 
          null); 
      //使用每一次都findviewById的方法来获得listview_item内部的组件 
      TextView tv_item = (TextView) view.findViewById(R.id.tv_item); 
      tv_item.setText(list.get(position)); 
      return view; 
    } 
 
    @Override 
    public Object getItem(int position) { 
      return null; 
    } 
 
    @Override 
    public long getItemId(int position) { 
      return 0; 
    } 
 
  } 
} 

@Override 
  public View getView(int position, View convertView, ViewGroup parent) { 
    View view; 
    // 判断convertView的状态，来达到复用效果 
    if (null == convertView) { 
      //如果convertView为空，则表示第一次显示该条目，需要创建一个view 
      view = View.inflate(MainActivity.this, R.layout.listview_item, 
          null); 
    } else { 
      //否则表示可以复用convertView 
      view = convertView; 
    } 
    // listview_item里只有一个textview 
    TextView tv_item = (TextView) view.findViewById(R.id.tv_item); 
    tv_item.setText(list.get(position)); 
    return view; 
  } 

TextView tv_item = (TextView) view.findViewById(R.id.tv_item);

private static class ViewHolder { 
  private TextView tvHolder; 
} 

@Override 
  public View getView(int position, View convertView, ViewGroup parent) { 
    View view; 
    ViewHolder holder; 
    // 判断convertView的状态，来达到复用效果 
    if (null == convertView) { 
      // 如果convertView为空，则表示第一次显示该条目，需要创建一个view 
      view = View.inflate(MainActivity.this, R.layout.listview_item, 
          null); 
      //新建一个viewholder对象 
      holder = new ViewHolder(); 
      //将findviewbyID的结果赋值给holder对应的成员变量 
      holder.tvHolder = (TextView) view.findViewById(R.id.tv_item); 
      // 将holder与view进行绑定 
      view.setTag(holder); 
    } else { 
      // 否则表示可以复用convertView 
      view = convertView; 
      holder = (ViewHolder) view.getTag(); 
    } 
    // 直接操作holder中的成员变量即可，不需要每次都findViewById 
    holder.tvHolder.setText(list.get(position)); 
    return view; 
  }