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Learning the Java Language
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Numbers and Strings
Summary of Numbers
You use one of the wrapper classes –
Byte,
Double,
Float,
Integer,
Long, or
Short –
to wrap a number of primitive type in an object. The Java compiler automatically
wraps (boxes) primitives for you when necessary and unboxes them, again when necessary.
The Number classes include constants and useful class methods. The MIN_VALUE and
MAX_VALUE constants contain the smallest and largest values
that can be contained by an object of that type.
The byteValue, shortValue,
and similar methods convert one numeric type to another.
The valueOf method converts a string to a number,
and the toString method converts a number to a string.
To format a string containing numbers for output, you can use the
printf() or format() methods in the
PrintStream class. Alternatively, you can use the NumberFormat
class to customize numerical formats using patterns.
The Math class contains a variety of class methods
for performing mathematical functions, including exponential, logarithmic,
and trigonometric methods. Math also includes basic arithmetic functions, such as
absolute value and rounding, and a method, random(),
for generating random numbers.
