ITEC120-ibarland (incl. office hrs)—info—lectures—labs—hws—java.lang docs—java.util docs

hw05:
gRUe, pt. I

Due Nov.05 (Mon) 17:00. Solution (.jar)

The Grand Repository of Underground Entertainment (gRUe) is a simple game of exploration, where an intrepid adventurer may journey through various rooms, collecting and leaving behind various treasures. gRUe will be written over the course of four weekly homeworks.

For part I, we will develop two classes: Explorer, and Treasure.
As usual, include javadoc code for each class. Write these comments before writing the actual code; the comments will help you focus on what the method does. PIs have been instructed to not help you on a method, if you don't have those comments already written.
Similarly, if you are requesting help on a method, and don't have all other already-written methods called and tested from your test method, you must do that before receiving later help.

1. A Treasure is a relatively simple class: every treasure has three attributes: a name, a description, and a weight (in lbs). Some examples might be:

   name: a small nugget
   description: Upon close inspection, the nugget glints of gold!
   weight: 0.05 lbs
   
   name: a multi-colored pen
   description: This fancy pen can write in blue, red, green, and plaid.
   weight: 0.1lbs
   
   name: chocolate egg
   description: The size of an ostrich egg, but made entirely of dark chocolate!
   weight: 35 lbs
   

   1. Create a class with those attributes.
   2. Write a constructor which takes the required information as parameters.
   3. Write a toString method for Treasures.
   4. Write a static method testTreasure which creates several Treasure instances, and prints them to the console window with System.out.println. (Make three examples, different from the one shown above.)
   5. Optional: Sometimes a Treasure's name pretty much is all the description you need. Overload the constructor so that if somebody creates a new Treasure but only provides a name and a weight, then the name is also used as the description.
      (You may even read about calling one constructor from inside another, to avoid repeated code.)
   6. There are two treasures which will we will need multiple instances of, in the world of gRUe: lint, and dirt (which each weigh 0). Write methods createLint() and createDirt(), which each return an appropriate newly-made Treasure. (These methods should be static, since they are not behaviors of specific Treasures; it makes sense to call this method even if no other Treasures have ever been constructed.)
   7. Revise TestTreasure to include a test of createLint.
   8. Write a Treasure method boolean isLint(). (Should this method be static? That is, does it make sense to call this method even if no Treasure have ever been created?)
      How can you tell if a Treasure instance was one created by createLint()? We'll presume¹ that just checking the instance's name will suffice. When comparing Strings, do you want to use == or .equals? Does your code have any magic numbers &hellp; or magic strings?
   9. Revise TestTreasure to include a test of isLint.
2. An Explorer has a name, and two pockets (left and right) which each contain one Treasure.
   1. Create a constructor which takes just a name. It creates a new Explorer with the given name, and lint in each pocket.
   2. Write a toString method for Explorers.
   3. Write a static testExplorer method which creates one explorer and prints it out to the console window. As you write further methods, add further tests to this method.
   4. Write a method String inventory(), which returns a detailed listing of the Explorer's two pockets.
   5. Write Treasure String dropLeft() replaces the contents of the left pocket with lint and returns a String saying what happened, e.g. “You drop a chocolate egg.”. Similarly, write TreasureString dropRight(Treasure).
   6. Write method String grab(Treasure), which takes a Treasure as a parameter.
      • If one pocket or the other contains lint, then this new Treasure is placed into such a pocket, and the method returns a message along the lines of “You drop a lint. You pick up a chocolate egg.”.
      • If neither pocket contains lint, then the pockets remain unchanged, and you return a message saying something like “Your pockets are full; you might want to drop something.”, followed by the Explorer's inventory. ²
3. Implement a weight limit for Explorers: if an Explorer tries to grab a Treasure which would bring the combined left- and right-pocket Treasures' weights above the limit, then the pocket stays the same, and it instead returns a message along the lines of “The chocolate egg is too heavy to pick up.”

ITEC120-ibarland (incl. office hrs)—info—lectures—labs—hws—java.lang docs—java.util docs

©2006, Ian Barland, Radford University Last modified 2006.Dec.12 (Tue)

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