Learning Basic datatypes , operators and statements in Java

1. DATA TYPES AND OPERATORS
AND STATEMENTS

2. Data types
2
Prof. Ashish Bhatia

3. Byte Ordering
3
JAVA
x86 and
x64
Prof. Ashish Bhatia

4. Floating Points - float
4
 Float [ 8byte = 64 bits]
 123.45 ? What is exponent and Significand
 31 – Sign Bit [ 1 bit ]
 23-30 – Exponent Field [ 8 bit ]
 0-22 - Significand [23 bit]
Prof. Ashish Bhatia

5. Floating Points
5
 Float [ 4byte = 32 bits]
Bits 30-23 Bits 0-22 Significand
Exponent
0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Bits 30-23 Bits 0-22 Significand
Exponent
1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Bits 30-23 Bits 0-22 Significand
Exponent
1 1 1 1 1 1 1 1 1 Any Non – zero value
Prof. Ashish Bhatia

6. Floating Points - double
6
Bits 62-52 Bits 51-0 Significand
Exponent
0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Bits 62-52 Bits 51-0 Significand
Exponent
1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Bits 62-52 Bits 51-0 Significand
Exponent
1 1 1 1 1 1 1 1 1 Any non-zero value
Prof. Ashish Bhatia

7. Super Type and Sub Type Relations
7
double
float
long
int
short char
byte
Prof. Ashish Bhatia

8. Using Literals
8
 Use l or L for long values else everything is int.
 Use f or F for Float values else everything is double.
 For Octal use 0
 For Hex use 0x or 0X
 used for special characters
 ‘n’ = New Line
 ‘t’ = Tab
 ‘017’ = Character constant
Prof. Ashish Bhatia

9. Legal Identifiers
9
 Must start with a letter, a currency character ($), or
a connecting character such as the underscore ( _ ).
Identifiers cannot start with a number!
 After the first character, identifiers can contain any
combination of letters, currency characters,
connecting characters, or numbers.
 In practice, there is no limit to the number of
characters an identifier can contain.
 Identifiers in Java are case-sensitive; foo and FOO
are two different identifiers.
Prof. Ashish Bhatia

10. Example
10
 int _a;
 int $c;
 int ______2_w;
 int _$;
 int this_is_a_very_detailed_name_for_an_;
 int :b;
 int -d;
 int e#;
 int .f;
 int 7g;
Prof. Ashish Bhatia

11. Unicode Escape in Java
11
 ufour hex number
 u0A85
Prof. Ashish Bhatia

12. Reference Datatypes
12
 Arrays
 Classes
 Interface
 Enum
 Annotation
Prof. Ashish Bhatia

13. Operators
13
 Arithmetic Operators
+ - * / %
 Conversion
 Widening
 Sub type to super type
 Narrowing
 Super Type to sub type
 Mixed Conversion
Prof. Ashish Bhatia

14. Operators
14
 Unary + and –
 String Concatenation
Prof. Ashish Bhatia

15. Operator
15
 Relational Operator
 < > <= >= == !=
 Logical Operator
 & | ^ ! && ||
 Bitwise Operator
 & | ^ ~ << >> >>>
 Increment and Decrement Operator [ ++ , -- ]
 Conditional Operator (? : )
 Assignment Operator
 instanceof
 new
Prof. Ashish Bhatia

16. Example
16
 int a = 60; /* 60 = 0011 1100 */
 int c = a << 2; /* 240 = 1111 0000 */
 int c = a >> 2; /* 15 = 1111 */
 int c = a >>> 2; /* 215 = 0000 1111 */
 What is int a = -60?
Prof. Ashish Bhatia

17. Statements
17
 Conditional
 if, if-else, switch-case
 Loop
 for, while, do-while
 break, continue, return
 Labeled break and continue
Prof. Ashish Bhatia

18. Brain Teasing Exercise
18
 x*=2+5
 boolean b = 100 > 99;
 5.0 == 5L
 if(x=0) {}
 if(b){}
 if(5 && 6) {}
 int x = 1;
int y=++x; // x++
System.out.println(y);
Prof. Ashish Bhatia

19. Output
19
 class Test{
public static void main(String[] args) {
int i = 42;
String s =
(i<40)?"life":(i>50)?"universe":"everyth
ing";
System.out.println(s);
}
}
Prof. Ashish Bhatia

20. Output
20
String s = "";
boolean b1 = true;
boolean b2 = false;
if((b2 = false) | (21%5) > 2) s += "x";
if(b1 || (b2 = true)) s += "y";
if(b2 == true) s += "z";
System.out.println(s);
Prof. Ashish Bhatia

21. More on Arrays
21
 int [] array; // recommended
 int array[];
 int [5] array; // ERROR
 Declaring an Array
 Constructing an Array
 int array[] = new Array[]
 int array[] = {1,2,3}
 int z[] = new int[] {1,2,3}
 int z[] = new int[3] {1,2,3}
Prof. Ashish Bhatia

22. Getting user input
22
import java.util.Scanner;
class Scan
{
public static void main(String args[])
{
Scanner s = new Scanner(System.in);
int x = s.nextInt();
System.out.println(x);
x = s.nextInt();
System.out.println(x);
}
}
Prof. Ashish Bhatia