Designing classes
The this operator
Make sure you read thoroughly.
1. Make the following changes to the BankAccount class:
a. Include a print statement in the getBalance() method to show the reference to the implicit parameter. Include “from method getBalance”
b. Include a print statement in both constructors, “from method default constructor” and “from constructor with parameter”.
2. Implement a test class, ThisOperatorTest. In this test, create an object of the class BankAccount and print it.
3. Include a commented paragraph at the end of the test class making a conclusion on the output. Make sure you explain what the this operator does in the two programs and compare them.
4. The following questions refer to calling by reference, by value and side effects:

• Modify your BankAccount class to include a new method, transfer. This method has two input parameters, double amount and double otherBalance from a different BankAccount object. The method takes money from the calling object’s balance and increases the balance from the other object by the “amount” value. The method also includes two print statements to display each object.

System.out.println(“From transfer( ), current object @: ” + _missing parameter);
System.out.println(“From transfer( ), otherAccount @: ” + otherBalance);

Create a test class, BankAccountTest1. In main:
• Create two BankAccount objects.
• Display the balance from both objects.
• Call the transfer method from one object to transfer money to the other object’s balance.
• Display both accounts’ balance.

A different approach to the same idea in 4:
• Modify your BankAccount class to include a new method, transfer. This method has two input parameters, double amount and BankAccount otherAccount. The method takes money from the calling object’s balance and increases the otherAccount’s balance by the “amount” value. The method also includes two print statements to display each object.

System.out.println(“From transfer( ), current object @: ” + _missing parameter);
System.out.println(“From transfer( ), otherAccount @: ” + otherAccount);

Look at edmodo.com for the different posts and due dates.

Classwork:
Write a program, YI_GPACalculator.java to read grades from a text file. The grades will have a specific structure so the marking periods, the subjects, and categories can be identified.

The file structure given here is just an example. You should notice it has some redundancy. You can configure your own structure to enable easier implementation.

[spoiler title=’gpadata.txt’]
Q1
Subject: English
Categories start:
Homework: .30
Classwork: .30
Test: .40
Categories end
Data:
Homework:
75
90
85
Classwork:
65
75
78
Test:
100
98
99
Subject: Math
Categories start:
Homework: .25
Classwork: .25
Test: .50
Categories end
Data:
Homework:
86
88
100
Classwork:
60
70
80
Test:
100
90
91
Q1 end
Q2
Subject: English
Categories start:
Homework: .30
Classwork: .30
Test: .40
Categories end
Data:
Homework:
95
80
81
Classwork:
55
95
88
Test:
93
100
85
Subject: Math
Categories start:
Homework: .25
Classwork: .25
Test: .50
Categories end:
Homework:
86
88
100
Classwork:
60
70
80
Test:
87
96
81
Q2 end
[/spoiler]

Here is some code that might help you read the file.

1. Using PU libraries: StdIn.java

/**
 * Calculate the GPA given a file with all the requirements.
 * Q1
 * Subject: English
 * Categories start:
 * Homework: .30
 * Classwork:
 * ....
 * ....
 * END
 * 
 * java GPACalculator1 < gpadata.txt
 * 
 */
public class GPACalculator1
{
    public static void main(String [] args)
    {

            while (StdIn.hasNextLine()) {
                String s1 = StdIn.readLine();
                System.out.println(s1);
            }
          
    
    }
    
}

1. Using java libraries:

import java.io.File;
import java.io.FileNotFoundException;
import java.util.Scanner;
/**
 * Calculate the GPA given a file with all the requirements.
 * Subject: English
 * Catgories beginning:
 * 
 */
public class GPACalculator2
{
    public static void main(String [] args)
    {
        
        File file = new File(args[0]);
    
        try {
    
            Scanner sc = new Scanner(file);
    
            while (sc.hasNextLine()) {
                String s1 = sc.nextLine();
                System.out.println(s1);
            }
            sc.close();
        } 
        catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    
    }
    
}

Before you get started writing code,
1. Draft a flowchart or a concise pseudocode.
2. Trace few grades from one subject for Q1 and Q2.
3. Manually calculate the GPA for the data used in the trace.
4. Confirm that your trace and calculation coincide.

Submit all your work to edmodo.com.

/**
 * Test of ArrayLists basic instructions
 * 
 * @ge
 * @4/16/18
 */
import java.util.ArrayList;

public class ArrayListTest
{
   public static void main(String [] args)
   {
        
       ArrayList myList = new ArrayList();
       //ArrayList myList = new ArrayList(); // more efficient - eliminates warning
       Integer x = new Integer(45); // creates Integer 45
       
       myList.add(x); // adds Integer 45 to myList
       myList.remove(x); // removes the value 45 from myList
       x = new Integer(100); // creates Integer 100 
       myList.add(0,x); // adds Integer 100 to the beginning of myList

       System.out.println(myList.get(0)); // print the first element 
       System.out.println(myList.size()); // print the number of elements
       
       // One step further
       myList.add(5);
       myList.add(-27);
       myList.add(55);
       myList.add(0,3);
   }
}

Classwork:

Let’s use the following documentation Java™ Platform, Standard Edition 8
API Specification to create our own resources: 

ArrayList

From the documentation copy and paste the following methods’ description:

* 1
* boolean add(E e)
*
* 2
* void add(int index, E element)

* Having two methods with the same name but different argument list
* is called OVERLOADING
*
* 3
* E get(int index)
*
* 4
* E set(int index, E element)
*
* 5
* int indexOf(Object o)
*
* 6
* boolean isEmpty()
* Returns true if this list contains no elements.
*
* 7
* E remove(int index)
*
* 8
* boolean remove(Object o)
*
* 9
* int size()

Resource:

Assignment:
ArrayListBasics_YI.java
Write a program that does the following:
Choose a meaningful and complete message for each item in the list.

1. It creates an ArrayList, anAList of 100 random integers between any values from 1 to 1000 and find the two consecutive integers with the smallest difference between the two of them.

2. It finds and prints with a message the largest value in anAList.

3. It finds and prints with a message the average value in anAList.

4. It prints all the numbers from anAList separated with a space and in one line.

5. It prints the numbers from anAlist separated by 3 spaces in 10 columns by 10 rows format. Use printf to achieve this format. Do not use tab: “\t”.

6. Prompt the user for an integer and replace the 10th Integer with this new one. Display a message to acknowledge wether it was found.

7. Prompt the user for a number and search for that number. Display the number and the index where it was found.

8. Remove 10th Integer and print a message with the number.

9. Print the number of elements the ArrayList anAlist contains.

Note: Use printf to keep all your numbers tab properly.

/**** Make sure your documentation includes the output ****/

In.java

Basic elements of a data type.

• API.
• Class.
• Access modifiers.
• Instance variables.
• Constructors.
• Instance methods.
• Variable names in methods.

Basic components that you need to understand to be able to build data types in Java.

NOTE:

You should be working on the programming assignment and gradient assignments before you start working on OOD programs.

Classwork/Homework: NO DUE DATE HAS BEEN ASSIGNED YET

These assignments are to be developed using the basic elements of data types.

Generating cryptograms. A cryptogram is obtained by scrambling English text by replacing each letter with another letter. Write a program, YI_Crypto1.java to generate a random permutation of the 26 letters and use this to map letters. Give example: Don’t scramble punctuation or whitespace.

Entropy. The Shannon entropy measures the information content of an input string and plays a cornerstone role in information theory and data compression.

            Shannon Entropy Calculator

Shannon is famous for having founded information theory.
It was proposed by Claude Shannon in 1948, borrowing upon the concept in statistical thermodynamics. Assuming each character i appears with probability p(_{i}), the entropy is defined to be H = – sum p(_{i}) log(_{2})p(_{i}), where the contribution is 0 if p(_{i}) = 0. Compute entropy of DNA sequence.
(a) Write a program, YI_Entropy1.java to read in a ASCII text string from standard input, count the number of times each ASCII character occurs, and compute the entropy, assuming each character appears with the given probabilities.
(b) Repeat part (a) but use Unicode.

February 26th, 2016

OOD Resources
BlueJ – Objects First

Chapter 2: VN 2.1 The naive ticket machine project

Chapter 2: VN 2.2 introduction to source code – fields and constructors

Chapter 2: VN 2.3 Creating, documenting and testing a new class

Chapter 3: VN 3.1 Fields of class types

Chapter 3: VN 3.2 Constructors and field initialization

Chapter 3: VN 3.3 Solving the 12-hour clock exercise