Static import

Static import is a feature introduced in the Java programming language that allows members (fields and methods) defined in a class as public static to be used in Java code without specifying the class in which the field is defined. This feature was introduced into the language in version 5.0.

The feature provides a typesafe mechanism to include constants into code without having to reference the class that originally defined the field. It also helps to deprecate the practice of creating a constant interface: an interface that only defines constants then writing a class implementing that interface, which is considered an inappropriate use of interfaces^[1].

The mechanism can be used to reference individual members of a class:

import static java.lang.Math.PI;
import static java.lang.Math.pow;

or all the static members of a class:

import static java.lang.Math.*;

For example, this class:

public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello World!");
        System.out.println("Considering a circle with a diameter of 5 cm, it has:");
        System.out.println("A circumference of " + (Math.PI * 5) + "cm");
        System.out.println("And an area of " + (Math.PI * Math.pow(2.5,2)) + "sq. cm");
    }
}

Can be shortened to:

import static java.lang.Math.*;
import static java.lang.System.out;
public class HelloWorld {
    public static void main(String[] args) {
        out.println("Hello World!");
        out.println("Considering a circle with a diameter of 5 cm, it has:");
        out.println("A circumference of " + (PI * 5) + "cm");
        out.println("And an area of " + (PI * pow(2.5,2)) + "sq. cm");
    }
}

References

Static Import (Oracle)

^ Java Practices