CISC 181 Introduction to Computer Science, Fall, 1998
Honors sections 80.81

First midterm test -- review sheet

Fri, Oct 9: In class midterm test on Java

Covered lectures/labs; all up to Oct 2. Thus GUI not covered on exam.
Covered reading: Chapters 2, 3, 4, 5 (pages 171-179), 7 (pages 251-276) Appendices: L, N, O

• Questions that examine how well you understand the "key concepts" listed in the text. For example,

  Key Concept Logical operators are a natural choice to implement a condition for a selection or repetition statement because they return a boolean value.

  • How would you implement a condition NOT using a logical operator? (answer by giving an example if statement)
  • What are the three logical operators?
• Questions based on lab exercises and programs
• Questions based on material discussed in class
• Any of the question forms
  1. true or false, such as:
     • Java is a compiled language
     • Java is an interpreted language
     • An interpreter translates from a high level language to machine language
     • A compiler translates from a high level language to machine language [remark: these are deliberately "tricky" questions designed to provoke thought during review and to point out a problem of true/false questions. However, every attempt will be made to avoid ambiguous/tricky questions on the exam.
  2. multiple choice,
  3. short answer (a few words or phrases),
  4. short explanations (a few sentences),
     (Examples of types 2,3,4 are scattered below.)
  5. program fragment to write, such as:
     • Suppose that x, y, and z are int variables that have been previously assigned values. Write a statement that prints the maximum of the three. Use no Java library classes except System.out.
  6. complete (but simple) program to write, such as:
     • Write a complete program file for an application that is designed to have two integers given on the command line. The program prints the average of two integers. This is a test of knowing the required elements and the exact syntax so will be graded rigorously with regard to those factors.
     • Estimation of Pi. Complete the following method definition:

       /** MonteCarloPi estimates Pi by choosing count points at random
       in a square and returning 4*(number in inscribed circle)/count.
       */
         public double MonteCarloPi(int count) {
         ...
         }
       

       You may assume the same class contains this method:

         private boolean inCircle( double x, double y, double radius ) {
           return x*x + y*y <= radius*radius;
         }
       

       This is a test of knowing how to organize the planned sequence of calculations, so will be graded primarily with respect to proper logical organization to achieve the goal. Less emphasis will be placed on syntax and proper declaration of variables used. Nonetheless, the syntax has to be good enough that we can discern your meaning.

• Fri, Oct 2: Finish XOR, color discussion, applet parameters Color XOR, PARAMs Example
  • What do you know about the setXORMode method of the Graphics class?
  • What are we using it for?
  • XOR has these properties: a ^ a = 0, a ^ 0 = a, (a ^ b) ^ c = a ^ (b ^ c), and (a ^ b) = (b ^ a).
    Which of these is properties to we need for our clock animation purposes? [ question is too arcane for midterm, but fun teaser to ask during review.]
• Wed, Sep 30: Implicit and explicit type conversion.
  Reading: number conversions, Java Chapter 5, pages 171-179.
  • Given the declarations

    double X = 1.0; int N = 1; long L = 1; 
    

    Which of the following is not a legitimate (compilable) assignment statement in java? (a little tricky)
    1. L = (int) X ;
    2. N = L ;
    3. L = N + (int) X ;
    4. N = ( (byte) L + (short) X ) ;
• Mon, Sep 28: Lab 3 Lab 3 is about clock hands moving
  • Write this method:

    /** degSine returns the sin of an angle given in degrees. */
      public double degSine( int angle_in_degrees ) {
      ...
      }
    

• Mon, Sep 28: Color, Arrays.
  Reading: arrays, Java Chapter 6, pages 207-217.
  • What are the R,G,B values of intense yellow?
  • Give R,G,B values for a less intense yellow.
  • Give a declaration of an array of colors named primaryColors containing initially the three colors red, green, blue.
  • Show how this array could be used in a Graphics.setColor method invocation.
• Fri, Sep 25: Animation basics. Sleep.
  • What is the difference between using a busy-wait and using a sleep, during an animation?
  • Why use either one? That is, what purpose do they both serve, what would happen if neither form of delay was used?
  • Why did we bury the sleep method call in another one, the one we called snooze ?
• Wed, Sep 23: On Graphics
  Reading: Java Chapter 7, pages 251-276. Discussion of clock applet.
  • Suppose g is an instance of the Graphics class. How many pixels are colored by this method invocation?
    g.drawRect(0,0,10,10);
  • ..by this call?
    fillRect(0,0,10,10);
  • Write method calls to to follwo this code and fill this oval in red, not overwriting the border of the oval.

      g.setColor( Color.black );
      g.drawOval( 10, 20, 30, 40 );
    

• Mon, Sep 21: Lab 2 PI example
  • How can a double value be converted to long?
• Mon, Sep 21: On Designing Classes CelestialBody class example.
  • What is in a class?
  • True or false:
    1. The first letter of the first word of every (top level) declaration in a class should be "p".
    2. The first letter of the first word of every declaration (including declarations nested within method definitions) in a class should be "p".
    3. The first letter of the first word of every declaration nested inside a method definition must not be "p". in a class should be "p".
• Fri, Sep 18: Program development strategies with review of Evens/ex3_16 program example.
  Reading: Java Chapter 3 & 4 should be Handed out programming exercises for lab 2.
  • True/False. You should never try to compile your program until all parts are completed.
  • What is to like, to not like, about the following variable names? x, n2, 2xN, TheDateOfTheFirstTransactionWithThisCustomer, date, custdate, StartDate, startDate, start_date, start_Date. j, jj, jjj, jana, banana, banan, otherBanan.
• Wed, Sep 16: Basic data types and classes primitive data types and
  • Name 3 primitive types.
  • What is a wrapper class. Illustrate by naming a primitive type, it's wrapper class, and a method of the Wrapper class.
• Mon, Sep 14: Language syntax, BNF language specification, Appendix N. control.
  • Appendix N - Java Syntax - Expected is to how to read it. For example, the following is in appendix N:

         ExclusiveOrExpression:
           AndExpression ( "^" AndExpression )*
    

    Assuming A, B, and C are valid AndExpressions, which of these is a valid ExclusiveOrExpression?
    1. B
    2. B^A
    3. B^A^C
    4. None of the above
    5. All of the above

    To answer such questions you should know how the regular expression works. If A B C are grammatical categories,
    A B refers to an instance of A followed by an instance of B
    (A | B) refers to an instance of A or an instance of B
    (A)* refers to zero or more instances of A in a row.
    [A] refers to an optional instance of A
    Thus the answer to the question is "All of the above"

  • What would the answer be if the BNF was as follows?

         ExclusiveOrExpression:
           AndExpression ( "^" | AndExpression )*
    

  • .. or

         ExclusiveOrExpression:
           AndExpression [ "^" | AndExpression ]*
    

• Mon, Sep 14: Lab1 ontogeny
  
• Fri, Sept 11: The language of computer language discussion:
  Program: declaration, definition, statement, expression
  Process: environment, state
  
  • What is the difference between a statement and an expression?
  • What is an expression statement?
  • What is an assignment statement?
  • Give an example of an expression statement. Make it a non-trivial statement, i.e. one that could do something useful in a program.
• Wed, Sept 9: Applications and Applets, or how to say Hello.
  • An application is
    1. Any program other than part of an Operating System
    2. A class containing a main method.
    3. Neither (1) nor (2).
    4. both (1) and (2).
• Fri, Sept 4: Discuss CS, use of javac (compiler), java (virtural machine)
  Reading: Java Chapter 2, pages 54-74

  Suppose I have a class file MyClass.class, compiled from MyClass.java, and designed to be an applet.

  • What import statement will be necessary in MyClass.java (because it is an applet class)?
  • What will first line of the class declaration of MyClass look like?
• Wed, Sept 2: Discussion of Computer Science, Computer Languages, course pragmas
  Reading: Java Chapter 2, pages 33-54
  • Which came first, Java, C++, or Pascal?
  • Name two features that many people might claim are part of the definition of a science. Name one that does not apply to Computer Science and one that does. For example "Proves it's principles by experimental testing of hypotheses" is one such feature.