4. Test

Karel Chapter 4 Test

You may not use any resource materials for this test.

Partners

New laws have been passed and now robots can get married. A robot who wants to get married must implement the Partner interface. The Partner interface consists of a public Partner getSpouse() method as well as a public void setSpouse(Partner x) and a public boolean isAvailable() method. When robots are delivered from the factory they do not have a partner.

1. Write the Partner interface.

   • getSpouse: return the current spouse
   • setSpouse: make the current spouse be the given robot
   • isAvailable: false if the Partner has a spouse

2. Create a LBot that implements the Partner interface. Example test code:

public static void main (String[] args) {
   LBot sally = new LBot(4,2,East,10);
   LBot harry = new LBot(5,2,East,4);
   sally.setSpouse(harry);
   if (sally.getSpouse() != harry) {
       System.err.println("Sally just married Harry. What's going on?");
   }
   if (sally.isAvailable()) {
       System.err.println("Sally should not still be available!");
   }
}

Marriage

3. The JusticeOfThePeaceBot can marry robots. The function is public boolean marry(Partner a, Partner b).
   • Write this function.
   • Only marry if both robots are available.
   • If either robot is unavailable, do not marry them!
   • Return true if the partners get married, false if the marriage fails.

public static void testMarry() 
{
   LBot sally = new LBot(4,2,East,10);
   LBot harry = new LBot(5,2,East,4);
   JusticeOfThePeaceBot judge = new JusticeOfThePeaceBot(1,1,East,0);
   
   boolean gotMarried = judge.marry(sally,harry);
   
   if ( ! gotMarried 
       || sally.getSpouse() != harry 
       || harry.getSpouse() != sally ) 
   {
       System.err.println("they did not get married!?");
   }
   
}

Relationships

Do one of the following:

4. (Know 4.8) The FindRelationship strategy is: move forward one step, if there is a robot there and it is available, change to NoStrategy, otherwise continue looking.

5. (No 4.8) The Courting strategy is created by Strategy s = new Courting(Partner x). The strategy checks to see if the partner is available, and if so it puts a beeper down. Write the Courting strategy.

public static void testCourt()
{
   LBot sally = new LBot(4,2,East,10);
   LBot harry = new LBot(5,2,East,4);
   
   Courting c = new Courting(sally);
   c.doIt(harry); // harry should place a beeper
   sally.setSpouse(sally); // married herself to make harry go away
   c.doIt(harry); // harry should do nothing
}