When scripts are written for each Java class, there is a pre-populated line that is present automatically. It is package coreJava. Since we have created a package in Java and placed all the Java classes into that coreJava package, we see it as package coreJava.

Packages are nothing but a set of classes and interfaces. For example, Java comes with a few built-in packages, such as java.length; if we import this package, only then can we access a basic fundamental method, such as public static void main, integer, or array. All these classes come from this java.lang package. It is important to define the package name, because without it, we cannot access the classes present inside the package. This is because java.lang is a default package and it comes within the Java compiler itself.

We have another package as well, java.util. We used this package when we worked on collections; we imported a java.util package. In order to work on ArrayList, this class is present in the java.util package...