1. Lecture 5 from (Chapter 4, pages 73 to 96)
Operators
Lecture 5 from (Chapter 4, pages 73 to 96)
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2. Review An introduction to Object-oriented programming
Arithmetic Operators
Bitwise operators
Relational Operators
Boolean Logical Operator
Assignment Operator
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3. An introduction to Object Oriented Programming - http://java. sun
Object-oriented Programming is the core of Java.
All java programms are object-oriented.
We need to understand what an object is, what a class is, how objects and classes are related, and how objects communicate by using messages.
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4. An overview of Object-oriented programming (1)
An object: An object is a software bundle of related variables and methods. Software objects are often used to model real-world objects you find in everyday life.
Messages: Software objects interact and communicate with each other using messages.
Class: A class is a prototype that defines the variables and the methods common to all objects of a certain kind.
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5. An overview of Object-oriented programming (2)
An inherientence: A class inherits state and behavior from its superclass. Inheritance provides a powerful and natural mechanism for organizing and structuring software programs.
An Interface: An interface is a contract in the form of a collection of method and constant declarations. When a class implements an interface, it promises to implement all of the methods declared in that interface.
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6. An object - We will introduce them one by one per week to build up your understanding
There are many examples of real-world objects. For example, our book, cat, pet etc.
These real-world objects share two characteristics, namely, : state and behavior.
For example, cats have state (color, hungry) and behavior (running , easting, sleeping).
Software objects are modeled following the real-world objects in that they too have state and behavior.
A software object maintains its state in one or more variables .
A variable is an item of data named by an identifier.
A software object implements its behavior with methods . A method is a function (subroutine) associated with an object.
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7. Common visual software object
Everything that the software object knows (state) and can do (behavior) is expressed by the variables and the methods.
For example, for a bicycle, would have variables that indicated the bicycle's current state: its speed is 7 km/hour,
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8. Arithmetic Operator – page 74
Operator Description
+ addition
- Subtraction
* Multiplication
/ Division
% Modules
++ Increment
Decrement
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9. Example – addition and subtraction
result
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10. Example – multiplication and division
result 0:
defined as integer
result
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11. Special operator Expression Equivalent expression a = a + 2; a +=2;
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12. Example of special operator
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13. Increment and Decrement
Expression Equivalent expression
a = a + 1; ++a;
a = a – 1; --a;
result
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14. Bitwise Operators – page 81
Operator Description
~ Bitwise unary NOT
& Bitwise AND
| Bitwise OR
^ Bitwise exclusive OR
>> Shift Right
<< Shift LEFT
>>> Shift Right with zero fill
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15. Operation - examples Operator Expression AND 1 & 1 = 1; 1& 0 = 0
~ 0 =~1; 1 =~0;
^ 0^ 0 = 0; 1^1 = 0; 1^0 =1; 0^1 = 1
>> x0010 = 0x >>1
<< 0x0001 = 0x <<1
>>> 0x1001 = 0x >>>1
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16. AND Example – bits, 0x (hexadecimal)
(0xf2)
(0xfe)
(and) &
(0xf2)
byte c = 0xf2;
byte d = 0xfe;
byte e = c & d; //e is 0xf2
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17. OR Example
(0xf2) (0xfe) (or) | (0xfe)
Example byte c = 0xf2; byte d = 0xfe; byte e = c | d; //e is 0xfe
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18. One’s complement 1111 0010 (0xf2) -------------- ~ 0000 1101 (0x0d)
Example byte c = 0xf2; byte e = ~c; //e is 0x0d
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19. EXCLUSIVE OR
(0xf2) (0xfe) (^) (0x0c) Example
byte c = 0xf2; byte d = 0xfe; byte e = c ^ d; //e is 0x0c
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20. Example
result
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21. Relational Operators Operator Description == Equal to != Not equal to
> Greater than
< Less than
>= Grater than or equal to
<= Less than or equal to
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22. Example int a = 3; int b = 4; boolean c = (a>b); //c is false
boolean d = (a<b); //c is true
boolean e = (a==b); //c is false
boolean d = (a>=b); //c is false
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23. Example
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24. SHIFT >> (right) by one bit
(0xf2) >> 1 (shift right by one bit)
(0x79)
Example byte c = 0xf2; byte e = c >>1; //e is 0x79
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25. SHIFT >> by two bits
(0xf2) >> 2 (shift right by one bit)
(0x3c) Example
byte c = 0xf2; byte e = c >>2; //e is 0x3c
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26. SHIFT << (left) by one bit
(0xf2) << 1 (shift right by one bit)
(0xe4)
Example byte c = 0xf2; byte e = c <<1; //e is 0xe4
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27. SHIFT << by two bits
(0xf2) >> 2 (shift right by one bit)
(0xc8) Example
byte c = 0xf2; byte e = c <<2; //e is 0xc8
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28. Results or bit operation (example)
(1 | 2) == (1 | 3) == (1 & 2) == (1 & 3) == (0 ^ 3) == (1 ^ 3) == (3 ^ 3) == ~0 == -1 (signed) or 255 (unsigned)
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29. Example of shift
result
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30. Relational Operators Operator Description == Equal to != Not equal to
> Greater than
< Less than
>= Grater than or equal to
<= Less than or equal to
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31. Example int a = 3; int b = 4; boolean c = (a>b); //c is false
boolean d = (a<b); //c is true
boolean e = (a==b); //c is false
boolean d = (a>=b); //c is false
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32. ? operator It is used to replace if-then-else statement
Expression1 ? Expression2: Expression 3;
If (expression1) is true, it will evaluate Expression 2, else Expression 3
int i = 3;
int j = 4;
int k;
(i > j)? k = 10: k = 20; // (i > j) is false, k =20
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33. Summary
Object-oriented Programming is the core of Java. Each object consists of states and behaviour.
Arithmetic Operators -- +, - * /, ++, --, %
Bitwise operators -- ~, ^, &, ^, >>, <<, >>>
Relational operators -- ==, !=, >, < , >=, <=
Boolean Logical Operator -- &. |, !, &=
? Operator – Exp1? Exp2: Exp3
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