import java.util.Math报找不到Math类

virmin

unix下
javac -d . Test.java
报找不到Math类

将
Test.java中
import java.util.Math;替换为import java.util.*;
编译通过

java.util中没有Math这个类吗？我看精华帖里有这么用的呀

白色乌鸦

Math 类在java.lang 下

virmin

[quote]原帖由 "白色乌鸦"]Math 类在java.lang 下[/quote 发表：

我倒，精华帖里居然是java.util.Math，好多地方也这样写...

sakulagi

哪个精华贴里的？

virmin

搞错了，不是精华，是置顶的
====JAVA初学教程进阶====

1.2 结构与构件
现在，我们从一个典型的Java源文件来了解一下Java程序涉及到的一些重要的构件，以及这些构件的结构。

代码:
1 package trades;

2 import java.util.Math;

   3 public class Quote extends Thread implements Tradable {

4   // Code goes in here

5 }

好象在精华里也看到过，找不着具体位置了，不能确定了

jerry_meng

Java.util.Math

Supplies static constants and methods
public static final double E // = 2.71828
public static final double PI // = 3.1415926
– Trigonometric ops (double ‡ double):sin, cos, tan, asin, acos, atan, atan2
– Rounding ops: ceil, floor, rint, round
– Exponentials: exp, pow, log, sqrt
– Other: abs, max, min, random


Java.lang.Math
contains methods for performing basic numeric operations such as the elementary exponential, logarithm, square root, and trigonometric functions.

virmin

楼上，那我为什么编译不过？是JDK不够新吗？我的是1.4

猫小

The Math class

Is part of the java.lang package

Contains class methods for performing basic numeric operations such as random number generation, rounding, absolute value, exponentiation, square root, logarithmic functions, and trigonometric functions .Contains two frequently used public field. These are:

Field        Usage

E              The double value that is closer than any other to e, the base of the natural logarithms
PI             The double value that is closer than any other to pi, the ratio of the circumference of a circle to its diameter


To display the value of e and the value of pi, you may run the following program:

1. public class App {
   
2.   public static void main(String[] args) {
   
3.     System.out.println("e = " + Math.E);
   
4.     System.out.println("pi = " + Math.PI);
   
5. 
   
6.   }
   
7. }

复制代码

Note: Because E and PI are fields of the Math class and not methods of the Math class, no parenthesis are coded after their name. Parenthesis are only used to indicate a method call.

Has a number of useful class methods. Among them are the following (with detailed parameter requirements and the returned data type omitted for brevity):

Method   Usage

abs()       Returns the absolute value of a number
ceil()        Returns the smallest (closest to negative infinity) double value that is not less than the argument and is equal to a mathematical integer
cos()        Returns the trigonometric cosine of an angle measured in radians
floor()      Returns the largest (closest to positive infinity) double value that is not greater than the argument and is equal to a mathematical integer
pow()      Returns the value of the first argument raised to the power of the second argument
random() Returns a double value greater than or equal to 0.0 and less than 1.0
round()   Rounds a real number to the nearest integer value
sin()        Returns the trigonometric sine of an angle measured in radians
sqrt()      Returns the correctly rounded positive square root of a double value
toDegrees() Converts an angle measured in radians to the equivalent angle measured in degrees
toRadians() Converts an angle measured in degrees to the equivalent angle measured in radians


Some of the above methods are "overloaded" to accept different parameter types.

Consult the help facility of your Java development environment or the Java API for more details.

for more reference:
http://javafaq.nu/article425.html
http://blog.chinaunix.net/articl ... 15419&blogId=18