public interface CharSequence
char values. This interface
 provides uniform, read-only access to many different kinds of char sequences. A
 char value represents a character in the Basic Multilingual Plane (BMP).
 
 This interface does not refine the general contracts of the
 equals and hashCode methods. The result of comparing two objects that implement CharSequence is
 therefore, in general, undefined. Each object may be implemented by a different class, and there
 is no guarantee that each class will be capable of testing its instances for equality with those
 of the other. It is therefore inappropriate to use arbitrary CharSequence instances as
 elements in a set or as keys in a map.
 
| Modifier and Type | Method and Description | 
|---|---|
| char | charAt(int index)Returns the  charvalue at the specified index. | 
| int | length()Returns the length of this character sequence. | 
| CharSequence | subSequence(int start,
           int end)Returns a new  CharSequencethat is a subsequence of this sequence. | 
| String | toString()Returns a string containing the characters in this sequence in the same order as this sequence. | 
char charAt(int index)
char value at the specified index. An index ranges from zero to
 length() - 1. The first char value of the sequence is at index zero, the
 next at index one, and so on, as for array indexing.index - the index of the char value to be returnedchar valueIndexOutOfBoundsException - if the index argument is negative or not less than length()int length()
chars in the sequence.chars in this sequenceCharSequence subSequence(int start, int end)
CharSequence that is a subsequence of this sequence. The subsequence
 starts with the char value at the specified index and ends with the
 char value at index end - 1. The length (in chars) of the
 returned sequence is end - start, so if start == end then an empty sequence is
 returned.start - the start index, inclusiveend - the end index, exclusiveIndexOutOfBoundsException - if start or end are negative, if end is greater than
         length(), or if start is greater than end