Type Cast Operator

There are two types of primitive type castings a possible.

1. implicit type casting
2. explicit type casting

Implicit Type Casting

1. Compiler is responsible for this type casting.
2. performed automatically where ever we are assigning smaller value to the bigger data type
3. It is also known as Widening  or up casting
4. There is no loss of information in this typecasting

Explicit Type Casting

1. Programmer is responsible for this type casting.
2. It requires where ever we are assigning bigger value to the smaller data type
3. It is also known as Narrowing or down casting
4. There may be a chance of loss of information in this typecasting.

The following is the list of all possible automatic promotions.

byte–> short–> int ( char )–> long–> float–> double–>

Ex:-1.

double d = 10 ;

 s.o.p ( d) ; // 10.0 

 compiler automatically 

Ex:-2.

int ch = 'a' ;

 s.o.p ( ch ) ; 10.0 

 promotes from 10 to 10.0 

The following conversion requires explicit type casting:-

byte <—- short <—- int ( char ) <—- float <—- double

Ex:-   byte b = 130 ; ( compile time error)

 byte b = ( byte ) 130 ; 

 s.o.p ( b) ; // -126 

Where we are assigning bigger datatype values to the smaller datatype by explicit typecasting, the most significant bits will be lost.

byte b = 130

 130 = 00000------0 

 b = 1000010 

 1111101 

  1111111 ==> 126 



 int a = 150 ; 

 byte b = ( byte ) a ; 

 short s  = ( short ) a ; 

 s.o.p ( b ) ; // -106 

 s.o.p ( s ) // 150 

Where we are trying to assign floating point values to the integral type by explicit type casting the digits after the decimal point will be lost.

double d = 10.235

 int a = ( int ) d ; 

 s.o.p ( a ) ; // 10 

 byte b = (byte ) 130.625 ; 

 s.o.p ( b ) ; // -126