The java.lang.package provides fundamental classes used in nearly every Java application. In this section, we will look at the Character and String classes.

This is the Character class:

public final class Character extends Object implements 
  Serializable, Comparable<Character>

This is one of the many core classes that has been around since the first version of Java. An object of the Character class consists of a single field of type, char.

This is the String class:

public final class String extends Object implements 
  Serializable, Comparable<String>, CharSequence

Strings (a string is another core-originating class) are immutable character strings.

Modifying the Character and String classes to support a newer version of Unicode, Version 7.0 for Java 9 and later, is an important step to help keep Java relevant as the premier programming language.