Java Reference
In-Depth Information
4.
Define a class called
BlogEntry
that could be used to store an entry for a Web log.
The class should have member variables to store the poster's username, text of the
entry, and the date of the entry using the
Date
class from Chapter 4. Add a con-
structor that allows the user of the class to set all member variables. Also add a
method,
DisplayEntry
, that outputs all of the member variables, and another
method called
getSummary
that returns the first 10 words from the text (or the
entire text if it is less than 10 words). Test your class from your main method.
5.
Define a class called
Counter
whose objects count things. An object of this class
records a count that is a nonnegative integer. Include methods to set the counter
to 0, to increase the count by 1, and to decrease the count by 1. Be sure that no
method allows the value of the counter to become negative. Include an accessor
method that returns the current count value and a method that outputs the
count to the screen. There should be no input method or other mutator meth-
ods. The only method that can set the counter is the one that sets it to zero. Also,
include a
toString
method and an
equals
method. Write a program (or pro-
grams) to test all the methods in your class definition.
6.
Write a grading program for a class with the following grading policies:
a. There are three quizzes, each graded on the basis of 10 points.
b. There is one midterm exam, graded on the basis of 100 points.
c. There is one final exam, graded on the basis of 100 points.
The final exam counts for 40 percent of the grade. The midterm counts for
35 percent of the grade. The three quizzes together count for a total of 25 per-
cent of the grade. (Do not forget to convert the quiz scores to percentages
before they are averaged in.)
Any grade of 90 or more is an A, any grade of 80 or more (but less than 90) is
a B, any grade of 70 or more (but less than 80) is a C, any grade of 60 or more
(but less than 70) is a D, and any grade below 60 is an F. The program should
read in the student's scores and output the student's record, which consists of
three quiz scores and two exam scores as well as the student's overall numeric
score for the entire course and final letter grade.
Define and use a class for the student record. The class should have instance
variables for the quizzes, midterm, final, overall numeric score for the course,
and final letter grade. The overall numeric score is a number in the range 0 to
100, which represents the weighted average of the student's work. The class
should have methods to compute the overall numeric grade and the final let-
ter grade. These last methods should be
void
methods that set the appropriate
instance variables. Your class should have a reasonable set of accessor and
mutator methods, an
equals
method, and a
toString
method, whether or
not your program uses them. You may add other methods if you wish.
7.
Write a
Temperature
class that has two instance variables: a temperature value
(a floating-point number) and a character for the scale, either
C
for Celsius or
F
for Fahrenheit. The class should have four constructor methods: one for each
