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
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
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