Static Imports in Java

Question

import static java.lang.Integer.*;
import static java.lang.Long.*;

public class StaticImortError  {

         public static void main(String args []) {
                 System.out.println(MAX_VALUE);
             }

}

Can anybody please explain why this program is showing compile time error, if I tried to use imports like import static java.lang.Integer.*; import static java.lang.Long.MAX_VALUE;, it ran fine and as expected displayed the maximum value of long data types, but with the above imports its showing error.

It's an ambiguous name. Both those classes have a static field named MAX_VALUE. The compiler can't determine which one you want. — Sotirios Delimanolis
– Sotirios Delimanolis, Commented Mar 6, 2014 at 21:05

Adam Arold · Accepted Answer · 2016-09-26 20:09:30Z

7

The problem is that you must explicitly state what to import in this case since both classes have a MAX_VALUE constant.

If you open the source code you'll see.

Since you can't assign an alias in java you are stuck with using Integer.MAX_VALUE/Long.MAX_VALUE.

Just a side note: I do not suggest a static import for Integer.MAX_VALUE (nor Long.MAX_VALUE) because if you have a rather big class and in the middle you reference MAX_VALUE then someone in the future will scratch his head asking "Whose max value are we talking about?"

edited Sep 26, 2016 at 20:09

answered Mar 6, 2014 at 21:07

Adam Arold

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1 Comment

Ken Lang Over a year ago

with regards to your side note - I've programmed in .Net for the past 15 years and am going through Java to gain experience with it - but are you saying that a Java IDE doesn't exist that has the "go to definition" feature that's in Visual Studio for the past 10 years.

Adam Arold · Accepted Answer · 2014-03-06 21:18:33Z

4

You're importing MAX_VALUE twice.

It's included both on java.lang.Integer.*; and java.lang.Long.*;

edited Mar 6, 2014 at 21:18

Adam Arold

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answered Mar 6, 2014 at 21:07

Andres

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Comments

willeM_ Van Onsem · Accepted Answer · 2014-03-06 21:07:01Z

0

In that case you import the static methods and fields associated with the given class.

For instance the Assert class contains a lot of methods like assertEquals.

Instead of writing each time Assert.assertEquals, you can write

import static org.junit.Assert.*;

and then use assertEquals in your code.

The reason why this doesn't work is because a call to MAX_VALUE is ambiguous between Long.MAX_VALUE and Integer.MAX_VALUE

answered Mar 6, 2014 at 21:07

willeM_ Van Onsem

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