Questions and Exercises: Classes
Questions
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Consider the following class:
public class IdentifyMyParts { public static int x = 7; public int y = 3; }
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What are the class variables?
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What are the instance variables?
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What is the output from the following code:
IdentifyMyParts a = new IdentifyMyParts(); IdentifyMyParts b = new IdentifyMyParts(); a.y = 5; b.y = 6; a.x = 1; b.x = 2; System.out.println("a.y = " + a.y); System.out.println("b.y = " + b.y); System.out.println("a.x = " + a.x); System.out.println("b.x = " + b.x); System.out.println("IdentifyMyParts.x = " + IdentifyMyParts.x);
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Exercises
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Write a class whose instances represent a single playing card from a deck of cards. Playing cards have two distinguishing properties: rank and suit. Be sure to keep your solution as you will be asked to rewrite it in Enum Types.
Hint:You can use the
assert
statement to check your assignments. You write:assert (boolean expression to test);
If the boolean expression is false, you will get an error message. For example,
assert toString(ACE) == "Ace";
should return
true
, so there will be no error message.If you use the
assert
statement, you must run your program with theea
flag:java -ea YourProgram.class
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Write a class whose instances represent a full deck of cards. You should also keep this solution.
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3. Write a small program to test your deck and card classes. The program can be as simple as creating a deck of cards and displaying its cards.