I have a task, which I was able to do with the use of simplest methods - arrays. Now I'd like to go further and redo it using some more complicated java features like collections, but I've never used anything more complicated than 2d matrix. What should I look at and how to start with it. Should Tower become a Collection ? And here's the task :

We have two classes - Tower and Block. Towers are built from Blocks. Ande here's sample code for testing:

 Block k1=new Block("yellow",1,5,4);
 Block k2=new Block("blue",2,2,6);
 Block k3=new Block("green",3,4,2);
 Block k4=new Block("yellow",1,5,4);

 Tower tower=new Tower();
 tower.add(k1,k2,k3);

 "Added 3 blocks."

 System.out.println(tower);

 "block: green, base: 4cm x 3cm, thicknes: 2 cm
 block: blue, base: 6cm x 2cm, thicknes: 2 cm
 block: yellow, base: 5cm x 4cm, thicknes: 1 cm"

 tower.add(k2);

 "Tower already contains this block."

 tower.add(k4);

 "Added 1 block."

 System.out.println(tower);

 "block: green, base: 4cm x 3cm, thicknes: 2 cm
 block: blue, base: 6cm x 2cm, thicknes: 2 cm
 block: yellow, base: 5cm x 4cm, thicknes: 1 cm      
 block: yellow, base: 5cm x 4cm, thicknes: 1 cm"

 tower.delete(k1);

 "Deleted 1 block"

 tower.delete(k1);

 "Block not in tower"

  System.out.println(tower);

 "block: blue, base: 6cm x 2cm, thicknes: 2 cm
 block: yellow, base: 5cm x 4cm, thicknes: 1 cm      
 block: yellow, base: 5cm x 4cm, thicknes: 1 cm"

Let's say I will treat Tower as a collection of blocks. How to perform search for specific block among whole collection ? Or should I use other interface ?