This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
1. There is a DroidFu library that you can use: it has a custom ImageView widget which automatically loads the image in bakground.
2. Apart from that you can take a look at Mark Murphy's ThumbnailAdapter class: cwac-thumbnail 3. See this tutorial. It uses a queue based implementation for executing tasks.
4. I started with something like this but then my code evolved to handle a lot of potential issues like the ones discussed here and here. You may also want to read this answer I wrote here
In case you are talking about List13.java(SlowAdapter) and List14.java(EfficientAdapter), then let me tell you they do not have any 'Lazy-Loading-logic' in them. Instead, these two files demonstrate two different patterns that one must use to make an efficient List in Android(you should consider including them whenever applicable).
SlowAdapter pattern demonstrates how you can avoid doing heavy, time consuming operations whilst the list is scrolling(Touch Scroll or Fling mode). When you scroll a List, getView() method of the adapter is called. If you do heavy operations in getView() like image fetches over network, file reads etc., this would slow down the scroll and even affect the scroll animation.
EfficientAdapter pattern, IMO, should be used in every implementation of a ListView. It makes use of view recycling and also avoid the expensive findViewById() call by employing a static holder class.