METHODS - Introduction to Java Programming: Comprehensive Version - page 219

22 }
23
24

return decimalValue;

25 }
26
27

public static int hexCharToDecimal( char ch) {

hex char to decimal
check uppercase

28 if (ch >= 'A' && ch <= 'F' )

29 return 10 + ch - 'A' ;

30 else // ch is '0', '1', ..., or '9'

31 return ch - '0' ;

32 }
33 }

Enter a hex number: AB8C
The decimal value for hex number AB8C is 43916

Enter a hex number: af71
The decimal value for hex number af71 is 44913

The program reads a string from the console (line 11), and invokes the hexToDecimal method
to convert a hex string to decimal number (line 14). The characters can be in either lowercase
or uppercase. They are converted to uppercase before invoking the hexToDecimal method.
The hexToDecimal method is defined in lines 17-25 to return an integer. The length of
the string is determined by invoking hex.length() in line 19.
The hexCharToDecimal method is defined in lines 27-32 to return a decimal value for
a hex character. The character can be in either lowercase or uppercase. Recall that to subtract
two characters is to subtract their Unicodes. For example, '5' - '0' is 5 .

6.8 Overloading Methods
Overloading methods enables you to define the methods with the same name as long
as their signatures are different.

Key
Point

The max method that was used earlier works only with the int data type. But what if you
need to determine which of two floating-point numbers has the maximum value? The solu-
tion is to create another method with the same name but different parameters, as shown in the
following code:

public static double max( double num1, double num2) {
if (num1 > num2)
return num1;
else
return num2;

}

If you call max with int parameters, the max method that expects int parameters will be
invoked; if you call max with double parameters, the max method that expects double
parameters will be invoked. This is referred to as method overloading ; that is, two methods
have the same name but different parameter lists within one class. The Java compiler deter-
mines which method to use based on the method signature.

method overloading