Description
Files to submit to Web-CAT:
• MidpointOfLineSegment.java
• TimeConverter.java
Specifications
Overview: You will write two programs this week. One will determine the midpoint of a line
segment given the x and y coordinates for the two end points of the line segment, and the other will
calculate the number of days, hours, minutes, and seconds from a raw measurement of seconds.
• MidpointOfLineSegment.java
Requirements: A program is needed that takes in the x and y coordinates for the two endpoints
of a line segment, and then calculates the midpoint of the line segment using the following
formula.
�������� = *
�, + �.
2 ,
�, + �.
2 2
where the coordinates of the two end points are (x1, y1) and (x2, y2) respectively.
Design: The main method of the program should read in the coordinates for the first point and
store them in variables (e.g., x1 and y1) of type double, read in the coordinates for the second
point and store them in variables (e.g., x2 and y2) of type double, and then use the formula above
to compute and print the x and y coordinates for the midpoint. The examples below show the
program output for various input values.
Example #1
Line # Program output
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Enter the coordinates for endpoint 1:
x1 = 0
y1 = 0
Enter the coordinates for endpoint 2:
x2 = 4
y2 = 4
For endpoints (0.0, 0.0) and (4.0, 4.0), the midpoint is (2.0, 2.0).
Note that lines 2, 3, 5, and 6 begin with tab.
Project: Variables and Expressions Page 2 of 3
Page 2 of 3
Example #2
Line # Program output
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8
Enter the coordinates for endpoint 1:
x1 = -1.5
y1 = -2.5
Enter the coordinates for endpoint 2:
x2 = 3.5
y2 = 7.5
For endpoints (-1.5, -2.5) and (3.5, 7.5), the midpoint is (1.0, 2.5).
Example #3
Line # Program output
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Enter the coordinates for endpoint 1:
x1 = .25
y1 = 2.5
Enter the coordinates for endpoint 2:
x2 = -1.75
y2 = 5.5
For endpoints (0.25, 2.5) and (-1.75, 5.5), the midpoint is (-0.75, 4.0).
Code: Create a Scanner object on System.in to read in the values for the coordinates. The values
of type double should be read in using the Scanner nextDouble method.
Test: You are responsible for testing your program, and it is important to not rely only on the
examples above. Remember that the input values for the x and y coordinates are doubles, so be
sure to test both positive and negative values (with and without a decimal point). You should use
a calculator or jGRASP interactions to check your answers. You may also find it useful to graph
the line segment.
• TimeConverter.java
Requirements: A digital timer manufacturer would like a program that accepts a raw time
measurement in seconds (of type int) and then then displays the time as a combination of days,
hours, minutes, and seconds. When a negative raw time measurement is entered, an appropriate
message is printed as shown in the first of the two examples below.
Design: The digital timer manufacturer would like the output to look as shown below when the
test values -1234 is entered as the raw time for one run and 1234567 is entered for another run.
Project: Variables and Expressions Page 3 of 3
Page 3 of 3
Line # Program output
1
2
Enter the raw time measurement in seconds: -1234
Measurement must be non-negative!
Line # Program output
1
2
3
4
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9
Enter the raw time measurement in seconds: 1234567
Measurement by combined days, hours, minutes, seconds:
days: 14
hours: 6
minutes: 56
seconds: 7
1234567 seconds = 14 days, 6 hours, 56 minutes, 7 seconds
Your program must follow the above format with respect to the output. Note that lines 4
through 7 for the amount 1234567 begin with tab (i.e., your output should use the escape
sequence for a tab).
Code: In order to receive full credit for this assignment, you must calculate the number of days,
hours, minutes, and seconds and store each of the values in separate variables. Create a Scanner
object on System.in to read in the value for the raw time using the nextInt() method. It is
recommended as a practice that you do not modify input values once they are read in and stored.
Test: You will be responsible for testing your program, and it is important to not rely only on the
example above. Assume that the amount entered can be any integer less than or equal to
2,147,483,647 (the maximum value for a 32 bit int) and greater than or equal to -2,147,483,648
(the minimum value for a 32 bit int).
Grading
Web-CAT Submission: You must submit both “completed” programs to Web-CAT at the same
time. Prior to submitting, be sure that your programs are working correctly and that have passed
Checkstyle. If you do not submit both programs at once, the submission will receive zero
points for correctness. Activity 1 describes how to create a jGRASP project containing both of
your files.
