chapter 2 Continuation

2.9 Instance operator:

                 a instance of B

                        |               \

                        |                 \

                        |                  \

       Object Reference      Class Name or Interface Name 

 EX1: String s = “surya”

System.out.println(s intanceof String); ------------gives output as true.

Ex2: Thread t = new Thread();

System.out.println(t instanceof Thread);------------gives true

System.out.println(t instanceof Object);------------gives true

System.out.println(t instanceof Runnable);------------gives true

Ex3: Object o = new Object();

System.out.println(o instanceof String);-----------gives false

Note: The type of a and B must be related, otherwise compile time exception like

incompatible types.

The null instance of any thing, the result is always false.

2.10. Type cast operator:

Type casting: Implicit type casting and Explicit type casting

Implicit type casting                                 |          Explicit type casting

This is responsibility of compiler             |            This is responsibility of programmer

No loss of information                              |            This result gives loss of information

Implicit type casting we can called          |             Explicit type casting we can called as Narrowing

as widening 

byte------short----}------>

                                          int----long-----float----double.

char----------------}------->

From left to right is implicit type casting.

From right to left is explicit type casting.

int a = 10;

byte b = a; gives compile time exception like required: byte, found: int.

int a = 10;

byte b = (byte)a;

This is explicit type casting. i.e. we are converting int type to byte type.

2.11. Conditional operator:

int a = (Boolean condition)?value if true: value if false;

int a = (b>40)?30:20;

2.12. New operator:

This operator is used for creation of objects.

[ ] is used for declaring and creating arrays.

class Demo

{

public static void main(String args[])

{

System.out.println(m(1)+m(3)*m(4)/m(5)+m(6));

}

public static int m(int i)

{

return i;

}

}

Output is: 9

1 + 3 * 4 / 5 + 6 = 1 + 12 / 5 + 6 = 1 + 2 + 6 = 9.

Before applying any operator all the operands must be evaluated from left to right and

then operators have to be applied based on the precedence.

2.13. Precedence of java operators:

Operator Precedence

Operators	Precedence
postfix	expr++ expr--
unary	++expr --expr +expr -expr ~ !
multiplicative	* / %
additive	+ -
shift	<< >> >>>
relational	< > <= >= instanceof
equality	== !=
bitwise AND	&
bitwise exclusive OR	^
bitwise inclusive OR	|
logical AND	&&
logical OR	||
ternary	? :
assignment	= += -= *= /= %= &= ^= |= <<= >>= >>>=