负载ListView

复杂的ListView的实现：

/**
	 * ListView的适配器
	 */
	private class AppManagerAdapter extends BaseAdapter{
		@Override
		public int getCount() {
			return userAppInfos.size()+1+systemAppInfos.size()+1;
		}
		@Override
		public View getView(int position, View convertView, ViewGroup parent) {
			AppInfo appInfo;
			if(position == 0){ //显示用户程序有多少个的小标签
				TextView tv = new TextView(getApplication());
				tv.setTextColor(Color.WHITE);
				tv.setBackgroundColor(Color.GRAY);
				tv.setText("用户程序:"+userAppInfos.size()+"个");
				return tv;
			}else if(position == (userAppInfos.size()+1)){
				TextView tv = new TextView(getApplicationContext());
				tv.setTextColor(Color.WHITE);
				tv.setBackgroundColor(Color.GRAY);
				tv.setText("系统程序:"+systemAppInfos.size()+"个");
				return tv;
			}else if(position <= userAppInfos.size()){
				int newPosition = position-1;
				appInfo = userAppInfos.get(newPosition);
			}else{
				int newPosition = position-1-userAppInfos.size()-1;
				appInfo = systemAppInfos.get(newPosition);
			}
			View view;
			ViewHolder holder;
			// 不仅需要检查是否为空，还要判断是否是合适的类型去复用
			if(convertView != null && convertView instanceof RelativeLayout){
				view = convertView;
				holder = (ViewHolder) view.getTag();
			}else{
				view = View.inflate(getApplicationContext(),R.layout.list_item_appinfo,null);
				holder = new ViewHolder();
				holder.iv_icon = (ImageView) view.findViewById(R.id.iv_app_icon);
				holder.tv_location = (TextView) view.findViewById(R.id.tv_app_location);
				holder.tv_name = (TextView) view.findViewById(R.id.tv_app_name);
				view.setTag(holder);
			}
			holder.iv_icon.setImageDrawable(appInfo.getIcon());
			holder.tv_name.setText(appInfo.getName());
			if(appInfo.isInRom()){
				holder.tv_location.setText("手机内存");
			}else{
				holder.tv_location.setText("外部存储");
			}
			return view;
		}
		@Override
		public Object getItem(int position) {
			return null;
		}
		@Override
		public long getItemId(int position) {
			return 0;
		}
	}
	static class ViewHolder {
		TextView tv_name;
		TextView tv_location;
		ImageView iv_icon;
	}