MATHEMATICAL FUNCTIONS, CHARACTERS, AND STRINGS - Introduction to Java Programming: Comprehensive Version - page 127

4.3.3 Casting between char and Numeric Types
A char can be cast into any numeric type, and vice versa. When an integer is cast into a char ,
only its lower 16 bits of data are used; the other part is ignored. For example:

char ch = ( char ) 0XAB0041 ; // The lower 16 bits hex code 0041 is
// assigned to ch

System.out.println(ch); // ch is character A

When a floating-point value is cast into a char , the floating-point value is first cast into an
int , which is then cast into a char .

char ch = ( char ) 65.25 ; // Decimal 65 is assigned to ch

System.out.println(ch); // ch is character A

When a char is cast into a numeric type, the character's Unicode is cast into the specified
numeric type.

int i = ( int ) 'A' ; // The Unicode of character A is assigned to i
System.out.println(i); // i is 65

Implicit casting can be used if the result of a casting fits into the target variable. Otherwise,
explicit casting must be used. For example, since the Unicode of 'a' is 97 , which is within
the range of a byte, these implicit castings are fine:

byte b = 'a' ;
int i = 'a' ;

But the following casting is incorrect, because the Unicode \uFFF4 cannot fit into a byte:

byte b = '\uFFF4' ;

To force this assignment, use explicit casting, as follows:

byte b = ( byte ) '\uFFF4' ;

Any positive integer between 0 and FFFF in hexadecimal can be cast into a character
implicitly. Any number not in this range must be cast into a char explicitly.
All numeric operators can be applied to char operands. A char operand is automati-
cally cast into a number if the other operand is a number or a character. If the other oper-
and is a string, the character is concatenated with the string. For example, the following
statements

numeric operators on
characters

int i = '2' + '3' ; // (int)'2' is 50 and (int)'3' is 51
System.out.println( "i is " + i); // i is 101
int j = 2 + 'a' ; // (int)'a' is 97
System.out.println( "j is " + j); // j is 99
System.out.println(j + " is the Unicode for character "
+ ( char )j); // 99 is the Unicode for character c
System.out.println( "Chapter " + '2' );

display

i is 101
j is 99
99 is the Unicode for character c
Chapter 2