Static Imports

import makes the names of classes and other types from another package part of our current namespace, so we can use them without fully-qualifying them.

• We still use an object reference to access fields and methods.

import com.example.utilities.parsing.Parser;
// ...
  Parser parser = new Parser();
  parser.parse();

We can access static fields and static methods without an object reference, using the class name.

//...
  public double getVolume() {
    double volume = 4.0/3.0 * java.lang.Math.PI * java.lang.Math.pow(this.radius, 3);
    return volume;
  }

Java allows us to import individual static field and method names into our current namespace using static imports.

import static java.lang.Math.PI;
import static java.lang.Math.pow;
//...
  public double getVolume() {
    double volume = 4.0/3.0 * PI * pow(this.radius, 3);
    return volume;
  }

import static java.lang.System.out; // out is a static field of java.lang.System

public class Hello {
  public static void main(String[] args) {
    out.println("Hello");
  }
}

• Only static fields and methods can be imported this way.

• The syntax is import static, not static import.

• You can use the * wildcard to import all static fields and methods of a class.

import static java.lang.Math.*;
//...
  public double getVolume() {
    double volume = 4.0/3.0 * PI * pow(this.radius, 3);
    return volume;
  }

Practice Exercise

Remember, import static imports static members of a single class. import imports individual classes or entire packages.

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