CharSequence

CharSequence is an abstract interface in the Java programming language. It represents a readable sequence of characters. The primary goal of CharSequence is to provide a common interface for various character-based data types, such as String, StringBuilder, and StringBuffer, allowing them to be treated uniformly.

Any class that implements the CharSequence interface must provide methods to access the characters within the sequence, determine its length, and retrieve a subsequence. The most commonly used methods are length(), charAt(int index), and subSequence(int start, int end). The length() method returns the number of characters in the sequence. The charAt(int index) method returns the character at the specified index. The subSequence(int start, int end) method returns a new CharSequence that is a sub-part of the original sequence, starting at the specified start index and ending at the specified end index (exclusive).

The CharSequence interface is particularly useful in scenarios where you need to write code that can operate on different types of character data without needing to know their specific implementation. For instance, a method that accepts a CharSequence parameter can work with any String, StringBuilder, or StringBuffer object passed to it. This promotes code reusability and flexibility. While String is the most prevalent implementation, the existence of CharSequence allows for more dynamic and adaptable character manipulation in Java applications.