Java static import with example – It can save time & typing efforts

We have already discussed static class, static variable, static method and static constructor. Here we will see another useful feature of java which is static import.

what’s the use of static imports?
Static imports are used to save your time and typing. If you hate to type same thing again and again then you may find such imports interesting.

Lets understand this with the help of below examples:

Example 1: Without Static Imports

class Demo1{
   public static void main(String args[])
   {
      double var1= Math.sqrt(5.0);
      double var2= Math.tan(30);
      System.out.println("Square of 5 is:"+ var1);
      System.out.println("Tan of 30 is:"+ var2);
   }
}

Output:

Square of 5 is:2.23606797749979
Tan of 30 is:-6.405331196646276

Example 2: Using Static Imports

import static java.lang.System.out;
import static java.lang.Math.*;
class Demo2{
   public static void main(String args[])
   {
      //instead of Math.sqrt need to use only sqrt
      double var1= sqrt(5.0);
      //instead of Math.tan need to use only tan
      double var2= tan(30);
      //need not to use System in both the below statements
      out.println("Square of 5 is:"+var1);
      out.println("Tan of 30 is:"+var2);
   }
}

Output:

Square of 5 is:2.23606797749979
Tan of 30 is:-6.405331196646276

Points to note:
1) Package import syntax:

import static java.lang.System.out;
import static java.lang.Math.*;

2) Note comments given in the above code.

When to use static imports?

If you are going to use static variables/methods a lot then it’s fine to use static imports. for example if you wanna write a code with lot of mathematical calculations then you may want to use static import.
Drawbacks
It makes the code confusing and less readable so if you are going to use static members very few times in your code then probably you should avoid using it. You can also use wildcard(*) imports.

Reference:
Head first java 2nd edition