Should I import a math library, and if so how?

Question

So I want to print out the math functions, "PI" and "E."

Here is how I'm trying to do it:

System.out.println(Math.PI);
System.out.println(Math.E);

I think I have to import the math library.

Did you try compiling this? – Oliver Charlesworth Feb 23 '14 at 18:01 — Oliver Charlesworth, Feb 23 '14 at 18:01

score 3 · Answer 1 · answered Feb 23 '14 at 18:01

E and PI are not functions, they're static fields (data members). That code will output their values correctly. You don't have to import anything, the Math class is in the java.lang package, which is imported by default. (It's the only package imported by default, I believe.)

score 2 · Answer 2 · answered Feb 23 '14 at 18:06

2

You don't have to import anything here. The java.lang.Math class should already be available as java.lang package is imported by default

answered Feb 23 '14 at 18:06

sadhu

1,429
8
14

score 0 · Answer 3 · answered Feb 23 '14 at 18:03

0

This works just fine:

/**
   <P>{@code java MathXmpl}</P>
 **/
public class MathXmpl  {
   public static final void main(String[] igno_red)  {
     System.out.println(Math.PI);
     System.out.println(Math.E);
   }
}

Output:

[C:\java_code\]java MathXmpl
 3.141592653589793
 2.718281828459045

Since Math is in the java.lang package, it does not need to be imported. java.lang is the "default package" and everything in it is already implicitly imported for you.

answered Feb 23 '14 at 18:03

aliteralmind

19,847
17
77
108

If that code works just fine, why do I get this error: "file not found: null: Java" – user3314801 Feb 23 '14 at 19:15
Oh, and on the next line, it says "javac " – user3314801 Feb 23 '14 at 19:15
There is nothing in your question-post that can cause a "file not found" error. You need to provide more information (code!) of exactly what you have tried, if you expect us to be able to help you. – aliteralmind Feb 23 '14 at 19:17
Copy code above into text file MathXmpl.java. Run `javac MathXmpl.java`. Then run `java MathXmpl`, which executes code in MathXmpl.class – Lutz Lehmann Feb 23 '14 at 22:23
This has nothing to do with the code. It means your Java runtime cannot find the compiled class! – aliteralmind Feb 23 '14 at 22:29

Should I import a math library, and if so how?

3 Answers3