Summary of Numbers数字的小结

You use one of the wrapper classes – Byte, Double, Float, Integer, Long, or Short – to wrap a number of primitive type in an object.您可以使用其中一个包装类–Byte、Double、Float、Integer、Long或Short–在对象中封装多个基元类型。The Java compiler automatically wraps (boxes) primitives for you when necessary and unboxes them, again when necessary.Java编译器会在必要时自动为您包装（装箱）原语，并在必要时再次拆箱。

The Number classes include constants and useful class methods.Number类包括常量和有用的类方法。The MIN_VALUE and MAX_VALUE constants contain the smallest and largest values that can be contained by an object of that type.常量MIN_VALUE和MAX_VALUE包含该类型对象可以包含的最小值和最大值。The byteValue, shortValue, and similar methods convert one numeric type to another.byteValue、shortValue和类似的方法将一种数字类型转换为另一种。The valueOf method converts a string to a number, and the toString method converts a number to a string.valueOf方法将字符串转换为数字，toString方法将数字转换为字符串。

To format a string containing numbers for output, you can use the printf() or format() methods in the PrintStream class.要格式化包含输出数字的字符串，可以使用PrintStream类中的printf()或format()方法。Alternatively, you can use the NumberFormat class to customize numerical formats using patterns.或者，您可以使用NumberFormat类使用模式自定义数字格式。

The Math class contains a variety of class methods for performing mathematical functions, including exponential, logarithmic, and trigonometric methods.Math类包含用于执行数学函数的各种类方法，包括指数法、对数法和三角法。Math also includes basic arithmetic functions, such as absolute value and rounding, and a method, random(), for generating random numbers.Math还包括基本的算术函数，如绝对值和舍入，以及生成随机数的方法random()。