ListView抽象化

private class TaskManagerAdapter extends BaseAdapter {
  private static final String TAG = "TaskManagerAdapter";
  @Override
  public int getCount() {
   SharedPreferences sp = getSharedPreferences("config", MODE_PRIVATE);
   if (sp.getBoolean("showsystem", false)) {
    return userTaskInfos.size() + 1 + systemTaskInfos.size() + 1;
   }else{
    return userTaskInfos.size() + 1 ;
   }
  }
  @Override
  public View getView(int position, View convertView, ViewGroup parent) {
   TaskInfo taskInfo;
   if (position == 0) {// 用户进程的标签
    TextView tv = new TextView(getApplicationContext());
    tv.setBackgroundColor(Color.GRAY);
    tv.setTextColor(Color.WHITE);
    tv.setText("用户进程：" + userTaskInfos.size() + "个");
    return tv;
   } else if (position == (userTaskInfos.size() + 1)) {
    TextView tv = new TextView(getApplicationContext());
    tv.setBackgroundColor(Color.GRAY);
    tv.setTextColor(Color.WHITE);
    tv.setText("系统进程：" + systemTaskInfos.size() + "个");
    return tv;
   } else if (position <= userTaskInfos.size()) {
    taskInfo = userTaskInfos.get(position - 1);
   } else {
    taskInfo = systemTaskInfos.get(position - 1
      - userTaskInfos.size() - 1);
   }
   View view;
   ViewHolder holder;
   if (convertView != null && convertView instanceof RelativeLayout) {
    view = convertView;
    holder = (ViewHolder) view.getTag();
    Log.i(TAG, "复用缓存。。" + position);
   } else {
    view = View.inflate(getApplicationContext(),
      R.layout.list_item_taskinfo, null);
    holder = new ViewHolder();
    holder.iv_icon = (ImageView) view
      .findViewById(R.id.iv_task_icon);
    holder.tv_name = (TextView) view
      .findViewById(R.id.tv_task_name);
    holder.tv_memsize = (TextView) view
      .findViewById(R.id.tv_task_memsize);
    holder.cb_status = (CheckBox) view.findViewById(R.id.cb_status);
    view.setTag(holder);
    Log.i(TAG, "创建新的view对象" + position);
   }
   holder.iv_icon.setImageDrawable(taskInfo.getIcon());
   holder.tv_name.setText(taskInfo.getName());
   holder.tv_memsize.setText("内存占用："
     + Formatter.formatFileSize(getApplicationContext(),
       taskInfo.getMemsize()));
   holder.cb_status.setChecked(taskInfo.isChecked());
   if (getPackageName().equals(taskInfo.getPackname())) {
    holder.cb_status.setVisibility(View.INVISIBLE);
   } else {
    holder.cb_status.setVisibility(View.VISIBLE);
   }
   return view;
  }
  @Override
  public Object getItem(int position) {
   return null;
  }
  @Override
  public long getItemId(int position) {
   return 0;
  }
 }
 static class ViewHolder {
  ImageView iv_icon;
  TextView tv_name;
  TextView tv_memsize;
  CheckBox cb_status;
 }