ITEC 120 2012fall dbraffitt ibarland

home—info—lects—labs—exams—hws
tutor/PIs—breeze (snow day)
Object120 + its docs—java.lang docs—java.util docs

lab06b
Objects intro
compound data (fields), continued

In lecture, we have seen class Song and class Robot. In lab, you have started writing class Student.

• Completed from last time:
  Data analysis:
  a student has a name, a sid, a gpa, a major, and a number of credit hours completed.

  Create a java class Student to represent this.

  Hint: (Compare that to “a song has an artist, a title, a length, and whether it's copyrighted”, and the code that resulted from that:

  class Song { String title; String artist; double length; // in seconds. boolean isCopyrighted; }

• Completed from last time:
  Constructor, and examples of the data.

  Task: Write a constructor for Students. Then, make a void testStudent function which (a) declares a variable to hold a Student, and (b) initializes those two variables (by calling the constructor).

  Hint: (Compare that to:

  class Song extends Object120 { String title; String artist; double length; // in seconds. boolean isCopyrighted; // Constructor: Song( String t, String a, double len, boolean isC ) { super( t, a, len, isC ); } // A test-driver, for song functions we'll write soon. void static testSong() { Song s1; s1 = new Song("Hit the floor", "Nickelback", 4*60+2, true ); Song s2; s2 = new Song("Everybody Knows", "Leonard Cohen", 3*60+27, true ); } }

• Consider the function onDeansRoll, which takes in a Student, and returns: is that student's gpa above 3.6?
  • Write three test cases function for onDeansRoll (two can use the variables you already have declared; have the third test case call the constructor without saving the result in a variable).

    Compare this to:

    // A test-driver, for song functions we'll write soon. void static testSong() { Song s1; s1 = new Song("Hit the floor", "Nickelback", 4*60+2, true ); Song s2; s2 = new Song("Everybody Knows", "Leonard Cohen", 3*60+27, true ); System.out.println( "Actual : " + diskSpaceUsed(s1) ); System.out.println( "Desired: " + (4*60+2)*0.0222 ); System.out.println( "Actual : " + diskSpaceUsed(s2) ); System.out.println( "Desired: " + (3*60+27)*0.0222 ); System.out.println( "Actual : " + diskSpaceUsed( new Song( "The Sound of Silence", ) ); System.out.println( "Desired: " + (3*60+27)*0.0222 ); }

  • Write a stub function for onDeansRoll.

    Compare this to:

    void static double disKSpaceUsed( Song myTune ) { }

  • Now, implement the body of the function. (as we just mentioned: to access an object's field from inside the function, use the “.” operator.)

    Compare this to:

    void static double disKSpaceUsed( Song myTune ) { return myTune.length * 0.0222; }

• Consider the function sameMajorAs, which takes in two Students and tells whether they have the same major.
  • Write a stub function for sameMajorAs.
  • Write two test cases function for sameMajorAs (one can use the variables you already have declared; have the other test case call the constructor without saving the result in a variable).
  • Finally, implement the function.

---

• Bonus: Write tests, a stub, and finally code for enrollNewStudent which takes in a name and sid, and returns a new Student with 0 hours enrolled and a 4.0gpa.

home—info—lects—labs—exams—hws
tutor/PIs—breeze (snow day)
Object120 + its docs—java.lang docs—java.util docs

©2012, Ian Barland, Radford University Last modified 2012.Oct.04 (Thu)

Please mail any suggestions (incl. typos, broken links) to ibarlandradford.edu