CS 163/164, Fall 2016

Lab 19 - Static versus Non-static

Wed-Fri, Nov. 16-18, 2016

Objectives of this Lab

1. Learn how to choose between class (static) and instance (non-static) variables, and
2. see how this influences the static and non-static modifier for associated methods, and
3. demonstrate that each object has its own copy of instance (non-static) variables, and
4. show that there is only one copy of class (static) variables.

Description

Utilities.java

    // Read the lines in a file into an array list 
    public static ArrayList<String> readLines(String infile);

    // Read the tokens in a file into an array list 
    public static ArrayList<String> readWords(String infile);
    
    // Count the frequency of specified character in array list
    public static int frequency(ArrayList<String> strings, char match);

FileStatistic.java

    // Constructor
    public FileStatistics(String filePath){

Instructions

1. Make an Eclipse project named R19.
2. Download Utilities.java and FileStatistics.java.
3. Download the three data files:
   • BenefitsOfJava.txt
   • Mars.txt
   • RobertFrost.txt
4. Look through the provided code, which your TA will help explain.
5. First, complete the method readWords in Utilities.java.
6. Second, complete the constructor in FileStatistics.java.
7. Third, write the test code in main.
8. Comments in the code will guide you through the process.
9. Finally, test the code by running main, no command line arguments are necessary.

Testing

BenefitsOfJava.txt
Lines: 19
Words: 144
Length: 915
Path: /s/bach/a/class/cs163/workspace/R19/BenefitsOfJava.txt

Mars.txt
Lines: 5
Words: 72
Length: 401
Path: /s/bach/a/class/cs163/workspace/R19/Mars.txt

RobertFrost.txt
Lines: 23
Words: 144
Length: 731
Path: /s/bach/a/class/cs163/workspace/R19/RobertFrost.txt

Words in all three files: 
[and, to, the, a]

Frequency of a for BenefitsOfJava.txt: 85, Mars.txt: 28, RobertFrost.txt: 57
Frequency of b for BenefitsOfJava.txt: 16, Mars.txt: 3, RobertFrost.txt: 12
Frequency of c for BenefitsOfJava.txt: 20, Mars.txt: 9, RobertFrost.txt: 9
Frequency of d for BenefitsOfJava.txt: 28, Mars.txt: 10, RobertFrost.txt: 36
Frequency of e for BenefitsOfJava.txt: 85, Mars.txt: 41, RobertFrost.txt: 68
Frequency of f for BenefitsOfJava.txt: 18, Mars.txt: 12, RobertFrost.txt: 8
Frequency of g for BenefitsOfJava.txt: 20, Mars.txt: 3, RobertFrost.txt: 14
Frequency of h for BenefitsOfJava.txt: 17, Mars.txt: 16, RobertFrost.txt: 36
Frequency of i for BenefitsOfJava.txt: 41, Mars.txt: 20, RobertFrost.txt: 30
Frequency of j for BenefitsOfJava.txt: 11, Mars.txt: 0, RobertFrost.txt: 1
Frequency of k for BenefitsOfJava.txt: 2, Mars.txt: 1, RobertFrost.txt: 7
Frequency of l for BenefitsOfJava.txt: 28, Mars.txt: 18, RobertFrost.txt: 26
Frequency of m for BenefitsOfJava.txt: 23, Mars.txt: 15, RobertFrost.txt: 7
Frequency of n for BenefitsOfJava.txt: 47, Mars.txt: 17, RobertFrost.txt: 37
Frequency of o for BenefitsOfJava.txt: 58, Mars.txt: 21, RobertFrost.txt: 49
Frequency of p for BenefitsOfJava.txt: 16, Mars.txt: 6, RobertFrost.txt: 5
Frequency of q for BenefitsOfJava.txt: 0, Mars.txt: 0, RobertFrost.txt: 1
Frequency of r for BenefitsOfJava.txt: 47, Mars.txt: 24, RobertFrost.txt: 32
Frequency of s for BenefitsOfJava.txt: 56, Mars.txt: 30, RobertFrost.txt: 32
Frequency of t for BenefitsOfJava.txt: 57, Mars.txt: 33, RobertFrost.txt: 51
Frequency of u for BenefitsOfJava.txt: 22, Mars.txt: 6, RobertFrost.txt: 10
Frequency of v for BenefitsOfJava.txt: 16, Mars.txt: 0, RobertFrost.txt: 8
Frequency of w for BenefitsOfJava.txt: 12, Mars.txt: 2, RobertFrost.txt: 18
Frequency of x for BenefitsOfJava.txt: 0, Mars.txt: 1, RobertFrost.txt: 0
Frequency of y for BenefitsOfJava.txt: 13, Mars.txt: 4, RobertFrost.txt: 11
Frequency of z for BenefitsOfJava.txt: 0, Mars.txt: 0, RobertFrost.txt: 0

Grading Criteria

• 100 points for perfect submission.
• 0 points for no submission, will not compile, submitted class file, etc.
• Preliminary Tests:
  • compileTest: checks that Utilities.java and FileStatistics.java compile. (0 points)
  • checkReadLines: Checks that readLines works correctly. (15 points)
  • checkReadWords: Checks that readWords works correctly. (20 points)
  • checkFrequency: Checks that frequency works correctly. (15 points)
  • checkConstructor: Checks that the constructor in FileStatistics works correctly. (25 points)
  • checkTestCode: Checks that the test code in main works correctly, based on output. (25 points)
• Final grading is identical to the preliminary tests.

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