Working with Packages in Java

Java packages are used to organize our code and to avoid naming conflicts. Packages strongly resemble folders like the ones found in file directory. Every package has a unique name so that class names can still be duplicated and still be used properly if you import it from the right package. There are two kinds of packages, the built-in ones and the ones you can create yourself.

Creating a Package

Create a package using the package keyword, and then the name of the package. Ensure that this is the top of the file.

package devices;

public class Phone {
    private String name;

    public Phone(String name) {
        this.name = name;
    }

    public int getName() {
        return name;
    }
}

This class now lives inside the devices package.

Importing Package

You can import a class of your choosing by using the import keyword and specifying the exact package and class name:

import java.lang.Math;

That, for example, imports the Math class only. This makes everything from Math available in whatever class you imported it into.

If you find yourself using multiple classes from the same package, you can just import an entire package to get all the classes inside available:

import java.lang.*;

This imports all the classes inside the java.lang package.