Android ListView中的ViewHolder的优化(逛博客时看到的优化)

    在看各个网站看博客文章的时候，看到了好多优化ViewHolder的文章。虽然，其中增加了判断，但是减少了ViewHolder的臃肿写法。他们是如何优化的呢？如下：

优化一:  

public static <T extends View> T getHolderView(View view, int id) {
		SparseArray<View> viewHolder = (SparseArray<View>) view.getTag();
		if (viewHolder == null) {
			viewHolder = new SparseArray<View>();
			view.setTag(viewHolder);
		}
		View childView = viewHolder.get(id);
		if (childView == null) {
			childView = view.findViewById(id);
			viewHolder.put(id, childView);
		}
		return (T) childView;
	}
           

优化二：

public static <T extends View> T getHolderView(View view, int id) {
		SparseArray<View> viewHolder = (SparseArray<View>) view.getTag();
		View childView;
		if (viewHolder == null) {
			viewHolder = new SparseArray<View>();
			view.setTag(viewHolder);
			// 先创建的ViewHolder自然没有缓存View所以不用判断
			childView = view.findViewById(id);
			viewHolder.put(id, childView);
		} else {
			childView = viewHolder.get(id);
			if (childView == null) {
				childView = view.findViewById(id);
				viewHolder.put(id, childView);
			}
		}
		return (T) childView;
	}