SE-1011 Software Development 1
Lab 4: Temperature Converter Revisited

Outcomes

• Continue to develop proficiency with the Java language
• Create Java mathematical expressions and formulas using various primitive datatypes
• Incorporate conditional control statements, such as if, else if, and else into a Java program to affect program control flow.

In this lab, you will write a program that uses a dialog box to prompt the user for a temperature in degrees Fahrenheit, computes the equivalent temperature in degrees Celsius, and outputs the result in a dialog box, along with an additional note indicating whether the temperature is frigid, cold, ideal, warm, or hot.

Detailed requirements

Study these requirements before implementing your program. This assignment requires you to construct a flowchart before you begin coding.

• After prompting the user for input, your program must detect (using if, else if, and else statements) whether the user:
1. entered a value (which may or may not be valid, but the input String contains at least 1 character)
2. pressed OK with no input (the input String is empty in this case)
3. pressed Cancel (the input String is null, regardless of whether the user actually typed something or not)

For the last two conditions, your program must print an error message to the user and terminate (end/exit). You can explicitly terminate by invoking the exit() method of the System class.

For the first condition, the user may have entered an invalid temperature (e.g. "a", or "-10_3" ). Handling this error condition is beyond what you learned so far in this course, so you don't have to worry about it for now. It is OK if your program crashes for this case.

• (This point is repeated from last week) The mathematical formula for converting from degrees F to degrees C is given by

  

  where T_c is the computed temperature in degrees Celsius
  T_F is the input temperature in degrees Fahrenheit

  • You must translate the math formula above into an equivalent Java formulation, using the correct operators for grouping, multiplication, and division.
  • You must create your own Java variables with meaningful names (and appropriate datatypes) to represent the values for the temperatures.
    
     
• When the user input  a valid temperature in F, your program  - in addition to outputting the equivalent temperature in C -, must (using if, else if, and else statements):
  • output the word "frigid" if the temperature is less than or equal to 0 C.
  • output the word "cold" if the temperature is above 0 but less than 20 C.
  • output the word "ideal" if the temperature is 20-25 C.
  • output the word "warm" if the temperature is above 25 but less than 35 C.
  • output the word "hot" if the temperature is above 35 C.
     

• Begin by drawing a (neat) flowchart - including decision conditions -  that illustrates the algorithm your program will implement.
   

• Every conditional test implemented in Java must be fully commented to let the reader know what you are doing in the case where the if condition is satisfied, as well as the case where the else or else if condition is satisfied instead.

Hints:

Test your program and make certain that it works correctly, both for valid and invalid inputs. As before, add comments to the end of your program that describe these tests and their results. Be sure your test values force your program through every condition that your program is designed to handle. Think about this carefully - there are quite a few different conditions.

Remember: While you may discuss the concepts with your classmates, you must write your own program. You may not copy or borrow code from your classmates. If you do, you will be given a grade of 0 and reported.

Lab Submission (due by end of lab)

Submit your assignment following these instructions:

1. Hand in your flowchart to your instructor.
2. Upload your .java file through WebCT (assignment "Lab 4: Revised Temperature Converter").

Your grade will be based on the following criteria:

• Meeting requirements; your program must compile and run. If you have trouble, you must come to see me. If you don't and you submit a program that does not compile or produce meaningful results will receive a grade of no higher than 50, even after reworking your program.
• Technical quality of your program. Technical quality consists of formatting, commenting, and following coding style guidelines we discussed in lectures.
• Spelling and grammar (Eclipse even has a built-in spell checker - make use of it!)
• Timeliness of submission as stated in the course policies.