Text Processing and More about Wrapper Classes

Contents

I. The Test Score Problem

II. Exercise

A. The Test Score Problem

• Professor Harrison keeps her students’ test scores in a Microsoft Excel spreadsheet. Figure below shows a set of five test scores for five students.

• In addition to manipulating the scores in Excel, Dr. Harrison wants to have a Java application that accesses them. Excel, like many commercial applications, has the ability to export data to a text file.

• When the data in a spreadsheet is exported, each row is written to a line, and the values in the cells are separated by commas. For example, when the data shown in the Figure is exported, it will be written to a text file in the following format:

87,79,91,82,9472,79,81,74,8894,92,81,89,9677,56,67,81,7979,82,85,81,90

• This is called the comma separated value file format. When you save a spreadsheet in this format, Excel saves it to a file with the .csv extension. Dr. Harrison decides to export her spreadsheet to a .csv file, and wants to have a Java program that reads the file and calculates the score average for each student. Help her to do this task.

Solution

1. Design

2. Test Case

3. Developing Test Class

1. Design

• Finding the main task

???

+ int[] getAverages(String csvFileName)

• Finding the class name

TestScoreProvider

+ double[] getAverages(String csvFileName)

2. Test Case

• Input: TestScores.csv

• Output: { 86.6, 78.8, 90.4, 72.0, 83.4 }

3. Developing Test Class

Develop class TestScoreProvider

• Ask TestScoreManager to provide test scores for calculating the averages

Develop TestScoreManager

TestScoreProvider

+ double[] getAverages(String csvFileName)

TestScoreManager

+ double[][] getTestScores(csvFileName)

Develop getScores()

B. Exercise

• The file SalesData.txt contains the dollar amount of sales that a retail store made each day for a number of weeks

1245.67,1490.07,1679.87,2371.46,1783.92,1461.99,2059.77

2541.36,2965.88,1965.32,1845.23,7021.11,9652.74,1469.36

2513.45,1963.22,1568.35,1966.35,1893.25,1025.36,1128.36

• Each line in the file contains seven numbers, which are the dales numbers for one week. The numbers are separated by a comma.

• Develop a program that opens the file and processes its contents. The program should be able to calculate:– The total sales for each week– The average daily sales for each week– The total sales for all of the weeks– The average weekly sales– The week number that had the highest amount of

sales– The week number that had the lowest amount of

sales

References

1. Starting Out with Java – From Control Structures through Data Structures, Chapter 10. Tony Gaddis and Godfrey Muganda, 2007