1. COMPUTER 2430 Object Oriented Programming and Data Structures I
Using NetBeans for class Object methods toString and equals
(no programs on inheritance now)
20 minutes for Quiz 1

2. Java String // Data type String is a class!
// All class names begin with a capital char
String firstName, lastName, str;
// Get a String object
firstName = new String("first");
str = "First";
// same as
// str = new String("First");
We do not need this:
import java.lang.*;
// Not just for String

3. Operator + String str = "First"; int x = 10;
// str = str + "appends to a string";
str += "appends to a string";
// "Firstappends to a string"
str += " need a space here“;
// "Firstappends to a string need a space here"
str = str + ',' + x;
// "Firstappends to a string need a space here,10“
// str += ',' + x; might be different!

4. Method length() public class String { . . . /**
Returns the number of chars in "this" string
Sample code: int count = str.length(); */
public int length() }
Both are instance methods

5. Method equals() public class String { . . . /**
Returns true when "this" string has the same
sequence of chars as string s
false otherwise
Sample code: if ( str1.equals(str2) ) */
public boolean equals( String s ) }
Both are instance methods

6. Example String str1, str2; Scanner sc = new Scanner( System.in );
str1 = new String("first");
str2 = sc.next(); // next string (token)
if (str1.equals(str2))
System.out.println("str1 is the same as str2.");
else
System.out.println("str1 is not the same as str2.");
System.out.println("str1 has " + str1.length() + " chars.");

7. Java String str1 = new String("first");
str2 = sc.next(); // input: first
if (str1.equals(str2))
System.out.println("equal.");
else
System.out.println("not equal.");
if (str1 == str2)
System.out.println("Same string.");
System.out.println("Not the same string.");

8. ADT: Student Data Name, Address, Phone, Email DOB GPA . . . Operations
Set/Get name

9. ADT: Professor Data Name, Address, Phone, Email DOB Tenured . . .
Operations
Set/Get name

10. Features of OOP Abstraction Encapsulation Data Hiding Inheritance
Polymorphism

11. ADT: Person Data Operations Name, Address, Phone, Email DOB . . .
Set/Get name

12. public class Person {
private String name, address, phone, ;
private Date dob;
. . .
public boolean setName (String s)
boolean valid = false;
if (s.length() > 1)
name = s;
valid = true; }
return valid;
public String getName()
return name;
...

13. /**
Will inherit all members from class Person,
including name and the two methods on name
public boolean setName (String s)
public String getName() */
public class Student extends Person {
private float gpa;
public boolean setGPA (float value)
public float getGPA()
. . . }

14. /**
Will inherit all members from class Person,
including name and the two methods on name
public boolean setName (String s)
public String getName() */
public class Professor extends Person {
private boolean tenured;
public boolean applyGrant (String grantName)
public void teachCourse (String courseName)
. . . }

15. public class CS2430Sx {
public static void main(String[] args)
Student std = new Student();
std.setName("Frank");
System.out.println("Student: " + std.getName());
Professor prof = new Professor();
prof.setName("Qi");
System.out.println("Professor: " +
prof.getName()); }

16. Features of OOP Abstraction Encapsulation Data Hiding Inheritance
Polymorphism

17. Prog 1 Due 10 pm, Friday, September 14
-2 by 10 pm, Saturday, September 15
-5 by 10 pm, Monday, September 17
No credit after 10 pm, September 17
Still have to complete the program!

18. Lab 2
Five (5) points
Due 10 pm, Friday, September 21

19. Last Day to Drop Classes

20. Quiz 1
30 Minutes
Close book
Close notes
Close computer