Introduction to Classes ,object,Methods and Strings

Introduction to Classes ,object,Methods and Strings

1. CSE 452: Programming Languages
Chapter 3

2. 2Organization of Programming Languages-Cheng (Fall 2004)
Contents

3. 3Organization of Programming Languages-Cheng (Fall 2004)

4. 4Organization of Programming Languages-Cheng (Fall 2004)

5. 5Organization of Programming Languages-Cheng (Fall 2004)

6. 6Organization of Programming Languages-Cheng (Fall 2004)

7. 7Organization of Programming Languages-Cheng (Fall 2004)

8. 8Organization of Programming Languages-Cheng (Fall 2004)

9. 9Organization of Programming Languages-Cheng (Fall 2004)

10. 10Organization of Programming Languages-Cheng (Fall 2004)

11. 11Organization of Programming Languages-Cheng (Fall 2004)

12. 12Organization of Programming Languages-Cheng (Fall 2004)
Java Introduction
A

13. 13Organization of Programming Languages-Cheng (Fall 2004)

14. 14Organization of Programming Languages-Cheng (Fall 2004)
Declaring/Creating Objects
in a Single Step
ClassName objectReference = new ClassName();
Example:
Circle myCircle = new Circle();

15. 15Organization of Programming Languages-Cheng (Fall 2004)
Differences between variables of
primitive Data types and object types

1
c: Circle
radius = 1
Primitive type int i = 1 i
Object type Circle c c reference
Created using
new Circle()

16. 16Organization of Programming Languages-Cheng (Fall 2004)
Constructors
Circle(double r) {
radius = r;
}
Circle() {
radius = 1.0;
}
myCircle = new Circle(5.0);
Constructors are a
special kind of
methods that are
invoked to construct
objects.

17. 17Organization of Programming Languages-Cheng (Fall 2004)
Constructors, cont.
A constructor with no parameters
is referred to as a default
constructor.
 
     
Constructors must have the
same name as the class itself.
 
     
Constructors do not have a
return type—not even void.
 
     
Constructors are invoked using
the new operator when an object is
created. Constructors play the
role of initializing objects.

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19. 19Organization of Programming Languages-Cheng (Fall 2004)

20. 20Organization of Programming Languages-Cheng (Fall 2004)

21. 21Organization of Programming Languages-Cheng (Fall 2004)

22. 22Organization of Programming Languages-Cheng (Fall 2004)

23. 23Organization of Programming Languages-Cheng (Fall 2004)

24. 24Organization of Programming Languages-Cheng (Fall 2004)

25. 25Organization of Programming Languages-Cheng (Fall 2004)

26. 26Organization of Programming Languages-Cheng (Fall 2004)

27. 27Organization of Programming Languages-Cheng (Fall 2004)

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30. 30Organization of Programming Languages-Cheng (Fall 2004)