USER-DEFINED METHODS - Java Programming: From Problem Analysis to Program Design - page 387

TABLE 7-1 Some Predefined Mathematical Methods and Named Constants (continued)

class Math (Package: java.lang )

x is of type double . Returns a value of type double , which is the
square root of x .
Example: sqrt(4.0) returns the value 2.0
sqrt(2.25) returns the value 1.5

sqrt(x)

x is of type double . Returns the cosine of x measured in radians.
Example: cos(0) returns the value 1.0
cos(PI / 3) returns the value 0.5000000000000001

cos(x)

x is of type double . Returns the sine of x measured in radians.
Example: sin(0) returns the value 0.0
sin(PI / 2) returns the value 1.0

sin(x)

x is of type double . Returns the tangent of x measured in radians.
Example: tan(0) returns the value 0.0

tan(x)

7

The method log10 is not available in Java versions lower than 5.0.

Java also provides methods, contained in the class Character , to manipulate characters.
Table 7-2 describes some of the methods of the class Character contained in the
package java.lang . As in Table 7-1, Table 7-2 shows the name of the method in bold
and gives examples of how the methods work.

TABLE 7-2 Some Predefined Methods for Character Manipulation

class Character (Package: java.lang )

Expression Description

ch is of type char . Returns true ,if ch is a digit; false
otherwise.
Example:
isDigit('8') returns the value true
isDigit('*') returns the value false

isDigit(ch)

ch is of type char . Returns true ,if ch is a letter; false
otherwise.
Example:
isLetter('a') returns the value true
isLetter('*') returns the value false

isLetter(ch)