8.5.1. WrClasses-WE4-P1

Subgoals for Writing a Class 4/4

1. Name it

2. Differentiate class-level (static) vs. instance/object-level variables

3. Differentiate class-level (static) vs. instance/object behaviors/methods

4. Define class variables (static) as needed ‘

   1. Name

   2. Data Type

   3. public / private / final

5. Define instance variables (that you want to be interrelated)

   1. Name

   2. Data Type

   3. private

6. Create constructor (behavior) that creates initial state of object

   1. public

   2. Same name as class

   3. No return type

   4. Default - no parameters

   5. Logic - initialize all variables

   6. Repeat as needed, adding parameters

7. Create 1 accessor and 1 mutator behaviors per attribute

1. Accessors

   1. Name is get_<attr_name>

   2. Public

   3. Return type same data type as attribute

   4. No parameters

   5. Logic - return value

2. Mutators

   1. Name is set_<attr_name>

   2. Public

   3. Return type is void

   4. Parameter is same data type as attribute

   5. Logic validates input parameter and sets attribute value

8. Write toString method

   1. public

   2. Returns String

   3. No parameters

   4. Logic - convert needed attributes to a format that can be printed

9. Write equals method

   1. public

   2. Returns boolean

   3. Parameter - instance of the class

   4. Logic - compare attributes for equity

10. Create additional methods as needed

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Classes-WE4-P1

Consider the SongType class you began in an earlier exercise, as illustrated in the following UML diagram.

For questions 36 - 39, fill in the code blanks to implement the toString method to print the song in the following format: SONG by ARTIST (X.XX) where X.XX is the length in minutes.

public ___A___ toString () {
   return ___B___ + " by " + ___C___ + "(" + ___D___ + ")";

Q36: Fill in Blank A.

• String
• int
• double
• void
• return

Q37: Fill in Blank B.

• void
• String
• title
• artist
• length

Q38: Fill in Blank C.

• void
• String
• title
• artist
• length

Q39: Fill in Blank D.

• void
• String
• title
• artist
• length

For questions 40 - 45, fill in the code blanks to implement the equals method, where two songs are equal if

public ___E___ equals (___F___ other) {
   return artist.___G___(other.___H___) &&
      title.___I___(other.___J___);
}

Q40: Fill in Blank E.

• void
• String
• boolean
• SongType
• other

Q41: Fill in Blank F.

• void
• String
• boolean
• SongType
• other

Q42: Fill in Blank G.

• artist
• title
• length
• other
• equals

Q43: Fill in Blank H.

• artist
• title
• length
• other
• equals

Q44: Fill in Blank I.

• artist
• title
• length
• other
• equals

Q45: Fill in Blank J.

• artist
• title
• length
• other
• equals

For questions 46 - 50, fill in the code blanks to implement a method called isLonger, which returns true if the song is longer than the song in the parameter.

public ___K___ isLonger (___L___ other) {
   return ___M___ > ___N___.___O___;
}

Q46: Fill in Blank K.

• void
• String
• boolean
• SongType
• other

Q47: Fill in Blank L.

• void
• String
• boolean
• SongType
• other

Q48: Fill in Blank M.

• artist
• title
• length
• other
• equals

Q49: Fill in Blank N.

• artist
• title
• length
• other
• equals

Q50: Fill in Blank O.

• artist
• title
• length
• other
• equals

public class main{ public static void main(String args[]){ } }

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