Defining Classes II - Absolute Java - page 281

returns the double value 199.98. If there is any possibility that the string named by
theString has extra leading or trailing blanks, you should instead use

Double.parseDouble(theString.trim())

The method trim is a method in the class String that trims off leading and trailing
whitespace, such as blanks.
If the string is not a correctly formed numeral, then the invocation of
Double.parseDouble will cause your program to end. The use of trim helps
somewhat in avoiding this problem.
Similarly, the static methods Integer.parseInt , Long.parseLong , and
Float.parseFloat convert from string representations to numbers of the
corresponding primitive types int , long , and float , respectively.
Each of the numeric wrapper classes also has a static method called toString that
converts in the other direction, from a numeric value to a string representation of the
numeric value. For example,

parseInt

Double.toString(123.99)

returns the string value "123.99" .
Character , the wrapper class for the primitive type char , contains a number of static
methods that are useful for string processing. Some of these methods are shown in Display
5.8. A simple example of using the static method toUpperCase of the class Character is
given in Display 5.9. As is typical, this program combines the string-processing methods of
the class String with the character-processing methods in the class Character .
There is also a wrapper class Boolean corresponding to the primitive type boolean .
It has names for two constants of type Boolean: Boolean . TRUE and Boolean.FALSE ,
which are the Boolean objects corresponding to the values true and false of the
primitive type boolean .

Character

Boolean

Display 5.8 Some Methods in the Class Character (part 1 of 2)

The class Character is in the java.lang package, so it requires no import statement.

public static char toUpperCase( char argument)

Returns the uppercase version of its argument . If the argument is not a letter, it is returned unchanged.
EXAMPLE
Character.toUpperCase('a') and Character.toUpperCase('A') both return 'A' .

public static char toLowerCase( char argument)

Returns the lowercase version of its argument . If the argument is not a letter, it is returned unchanged.
EXAMPLE
Character.toLowerCase('a') and Character.toLowerCase('A') both return 'a' .

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