Java The Complete Reference, Seventh Edition

The CharSequence Interface

TheCharSequenceinterface defines methods that grant read-only access to a sequence of

characters. These methods are shown in Table 16-22. This interface is implemented byString,

StringBuffer, andStringBuilder. It is also implemented byCharBuffer, which is in the

java.niopackage (described later in this book).

The Comparable Interface

Objects of classes that implementComparablecan be ordered. In other words, classes that

implementComparablecontain objects that can be compared in some meaningful manner.

Comparable is generic and is declared like this:

interface Comparable<T>

Here,Trepresents the type of objects being compared.

TheComparableinterface declares one method that is used to determine what Java

calls thenatural orderingof instances of a class. The signature of the method is shown here:

int compareTo(Tobj)

Chapter 16: Exploring java.lang 433

Method Description

final String name( ) Returns the unaltered name of the invoking constant.

final int ordinal( ) Returns a value that indicates an enumeration

constant’s position in the list of constants.

String toString( ) Returns the name of the invoking constant. This

name may differ from the one used in the

enumeration’s declaration.

static <T extends Enum<T>> T

valueOf(Class<T>e-type, Stringname)

Returns the constant associated withnamein the

enumeration type specified bye-type.

TABLE 16-21 The Methods Defined byEnum(continued)

Method Description

char charAt(intidx) Returns the character at the index specified byidx.

int length( ) Returns the number of characters in the invoking

sequence.

CharSequence

subSequence(intstartIdx, intstopIdx)

Returns a subset of the invoking sequence beginning at

startIdxand ending atstopIdx–1.

String toString( ) Returns theStringequivalent of the invoking sequence.

TABLE 16-22 The Methods Defined byCharSequence