1. COMPUTER 2430 Object Oriented Programming and Data Structures I
Day1 on Thursday, before lab1

2. Lab1 Due 10 pm, Friday, September 7 -1 by 10 pm, Saturday, September 8
-2 by 10 pm, Monday, September 10

3. Features of OOP Abstraction Data Encapsulation Data Hiding
(Inheritance)
(Polymorphism)

4. public class ScoresList{
// Private data members
private final int MAX_SIZE = 10;
private int scores[] = new int[MAX_SIZE];
private int numValues = 0;
// Public methods (operations)
public boolean appendScore ( int score )
...
public boolean delete ( int score )
public float average()
public void print()
// Private methods (helper methods)
private int find ( int score ) }

5. public class ScoresList{
// Private data members
// Public methods (operations)
// Private methods
// Test Bed main for the class
public static void main( String [] args )
ScoresList scores;
scores = new ScoresList();
scores.print();
scores.appendScore(5);
. . . }

6. // Application using class ScoresList
// In the same project with class ScoresList
public class Prog1 {
public static void main( String [] args )
ScoresList scores = new ScoresList();
scores.print();
scores.appendScore(5);
if (scores.appendScore(7))
System.out.println( “Value 7 is added.”);
else
System.out.println( “Value 7 is not added.”);
. . . }

7. Input from key board (System.in).
import java.util.Scanner;
public class Prog1 {
public static void main( String [] args )
ScoresList scores = new ScoresList();
int score;
Scanner sc = new Scanner( System.in );
score = sc.nextInt();
scores.appendScore(score);
if (scores.appendScore(score))
System.out.println(“Value ” + score +
“ is added.”);
else
System.out.println( “Value ” + score +
“ is not added.”);
. . . }
Input from key board (System.in).

8. import java.util.Scanner;
import java.io.File;
public class Prog1 {
public static void main( String [] args )
ScoresList scores = new ScoresList();
int score;
Scanner sc;
try
// Input from a file if the file exists
sc = new Scanner( new File("Lab1_1.in") ); }
catch (Exception ex)
// Input from System.in (keyboard) if no input file
sc = new Scanner( System.in );
. . .
Input from an file.
Input file Prog1_1.in in the project folder, not inside src.

9. Input File Inside NetBeans Other Text editors such as Notepad
New File
Category: Other
Type: Empty
Name: Prog1_1.in
Folder: Prog1
Copy and paste from the instruction
Other Text editors such as Notepad
Not Word documents

10. Adding Array Elements private final int MAX_SIZE = 10;
private int intArray[] = new int[MAX_SIZE];
private valCount = 0;
int xVal, index = 0;
Scanner sc;
// set up the scanner
xVal = sc.nextInt();
// Insert xVal at the beginning of intArray
intArray[0] = xVal;
valCount ++;

11. Adding Array Elements private final int MAX_SIZE = 10;
private int intArray[] = new int[MAX_SIZE];
private valCount = 0;
/**
intArray[] has 5 values: valCount is 5
New value xVal
Store xVal at the end (as the 6th element)
What’s the index value for the new xVal? */
intArray[5] = xVal;
// what’s the value of valCount after adding?
valCount ++;

12. Adding Array Elements Correct? private final int MAX_SIZE = 10;
private int intArray[] = new int[MAX_SIZE];
private valCount = 0;
/**
intArray[] has valCount values
New value xVal
Store xVal at the end */
intArray[valCount] = xVal;
++ valCount;
Correct?
The array could be full!

13. Adding Array Elements private final int MAX_SIZE = 10; // const
private int intArray[] = new int[MAX_SIZE];
private valCount = 0;
/**
intArray[] has valCount values
New value xVal
Store xVal at the end */
if (valCount < MAX_SIZE ) {
intArray[valCount] = xVal;
++ valCount; }
else
//Cannot insert

14. Using ++ in Array Index if (valCount < MAX_SIZE ) {
intArray[valCount] = xVal;
valCount ++; }
else
//Cannot insert
// Yes! The same result: increasing after using it
if ( valCount < MAX_SIZE )
intArray[valCount ++] = xVal; // Correct?

15. Using ++ in Array Index if (valCount < MAX_SIZE ) {
intArray[valCount] = xVal;
valCount ++; }
else
//Cannot insert
// No! Increasing before using it.
if ( valCount < MAX_SIZE )
intArray[++ valCount] = xVal; // Correct?

16. Deleting Array Elements
/**
intArray[] has 9 values: intArray[0] to intArray[8]
Removing the element at index 6
Keeping all elements together in the same order */ 10 15 20 50 33 40 55 60 39 ? 10 15 20 50 33 40 60 39 ?
intArray[6] = intArray[7];
intArray[7] = intArray[8];
valCount --;
Don’t worry about intArray[8] as long as valCount is updated!

17. Deleting Array Elements
/**
intArray[] has 9 values: intArray[0] to intArray[8]
Removing the element at index 1
Keeping all elements together in the same order */ 10 15 20 50 33 40 55 60 39 ? 10 20 50 33 40 55 60 39 ?
Moving intArray[i+1] to intArray[i] for i = 1, (or 8?)
valCount --;
Need a for loop
Start and Stop?

18. Deleting Array Elements
/**
intArray[] has valCount values (valCount <= MAX_SIZE)
Removing the element at index (between 0 and valCount – 1)
Keeping the order of other elements */ 10 50 33 60 39 44 ?
index
valCount-2
valCount-1 10 33 .. 39 44 ?
valCount-1
// Where to start?
// Where to stop?
for (int i = index; i < valCount – 1; i ++)
intArray[i] = intArray[i + 1];
valCount --;

19. Deleting Array Elements
/**
intArray[] has valCount values (valCount <= MAX_SIZE)
Removing the element at index (between 0 and valCount – 1)
Keeping the order of other elements */ 10 50 33 60 39 44 ?
index
valCount-1 10 33 .. 39 44 ?
index
valCount-1
// This might be better
valCount --;
for (int i = index; i < valCount; i ++)
intArray[i] = intArray[i + 1];

20. Linear Search public class IntegerList {
private final int MAX_SIZE = 50;
private int intArray[] = new int[MAX_SIZE];
private int valCount = 0;
/**
Tries to find the FIRST occurrence of intValue in the list.
@param intValue to find
@return index of the FIRST occurrence of intValue,
-1 if not found */
public int find( int target )
for (int i = 0; i < valCount; i++)
if (intArray[i] == target)
return i;
return -1; }

21. Linear Search public class IntegerList {
private final int MAX_SIZE = 50;
private int intArray[] = new int[MAX_SIZE];
private int valCount = 0;
/**
Tries to find the LAST occurrence of intValue in the list.
@param intValue to find
@return index of the LAST occurrence of intValue,
-1 if not found */
public int find( int target )
// ??? }

22. Casting Integer to Float
int numValues, sum = 0;
// Loop through and sum up the scores in the array
ave = (float)sum / (float)numValues;

23. ++, --, +=, -= count ++; count = count + 1; index --;
index = index - 1; // 0.5 points off for Prog1
xVal += someVal;
xVal = xVal + someVal; // 1 point off for Prog2
yVal -= someVal;
yVal = yVal – someVal; // How many off for Prog3?

24. Don’t Over Do it!
Never use ++ or -- on an expression that appears more than one in the statement.
intArray[++ index] = index + 10;
intArray[index --] = index + 10;
x = x x;
// Very bad!
// Lose Points!

25. Program1 Due Time: 10 pm, Friday, September 14 Class ScoresList
Class Prog1

26. Software Development Grand Rules for CS 2430

27. Lab Assistant
Lab 206
Monday - Thursday
3:00 – 5:00