- Type Parameters:
- T- the type of objects that this object may be compared to
- All Known Subinterfaces:
- ArrayType,- ByteValue,- CharValue,- ChronoLocalDate,- ChronoLocalDateTime<D>,- Chronology,- ChronoZonedDateTime<D>,- ClassType,- Delayed,- DoubleValue,- Field,- FloatValue,- IntegerValue,- InterfaceType,- LocalVariable,- Location,- LongValue,- Method,- Name,- Path,- ProcessHandle,- ReferenceType,- RunnableScheduledFuture<V>,- ScheduledFuture<V>,- ShortValue
- All Known Implementing Classes:
- AbstractChronology,- AbstractRegionPainter.PaintContext.CacheMode,- AccessFlag,- AccessFlag.Location,- AccessMode,- AclEntryFlag,- AclEntryPermission,- AclEntryType,- AssociationChangeNotification.AssocChangeEvent,- AttributeTree.ValueKind,- Authenticator.RequestorType,- BigDecimal,- BigInteger,- Boolean,- Byte,- ByteBuffer,- Calendar,- CardTerminals.State,- CaseTree.CaseKind,- CatalogFeatures.Feature,- CertPathValidatorException.BasicReason,- Character,- Character.UnicodeScript,- CharBuffer,- Charset,- ChronoField,- ChronoUnit,- ClassFileFormatVersion,- ClientInfoStatus,- CollationKey,- Collector.Characteristics,- Component.BaselineResizeBehavior,- CompositeName,- CompoundName,- ConversionComparator.Comparison,- CRLReason,- CryptoPrimitive,- Date,- Date,- DayOfWeek,- Desktop.Action,- Diagnostic.Kind,- Dialog.ModalExclusionType,- Dialog.ModalityType,- DirectMethodHandleDesc.Kind,- Doclet.Option.Kind,- DocletEnvironment.ModuleMode,- DocTree.Kind,- DocumentationTool.Location,- Double,- DoubleBuffer,- DrbgParameters.Capability,- DropMode,- Duration,- ElementKind,- Elements.Origin,- ElementType,- Enum,- File,- FileTime,- FileVisitOption,- FileVisitResult,- Float,- FloatBuffer,- FocusEvent.Cause,- FormatStyle,- Formatter.BigDecimalLayoutForm,- FormSubmitEvent.MethodType,- Future.State,- GraphicsDevice.WindowTranslucency,- GregorianCalendar,- GroupLayout.Alignment,- HandlerResult,- HijrahChronology,- HijrahDate,- HijrahEra,- HotSpotDiagnosticMXBean.ThreadDumpFormat,- HttpClient.Redirect,- HttpClient.Version,- InquireType,- Instant,- IntBuffer,- Integer,- IsoChronology,- IsoEra,- JapaneseChronology,- JapaneseDate,- JavaFileObject.Kind,- JConsoleContext.ConnectionState,- JDBCType,- JTable.PrintMode,- KeyRep.Type,- LambdaExpressionTree.BodyKind,- LayoutStyle.ComponentPlacement,- LdapName,- LinkOption,- LocalDate,- LocalDateTime,- Locale.Category,- Locale.FilteringMode,- Locale.IsoCountryCode,- LocalTime,- Long,- LongBuffer,- MappedByteBuffer,- MemberReferenceTree.ReferenceMode,- MemoryType,- MethodHandles.Lookup.ClassOption,- MinguoChronology,- MinguoDate,- MinguoEra,- Modifier,- ModuleDescriptor,- ModuleDescriptor.Exports,- ModuleDescriptor.Exports.Modifier,- ModuleDescriptor.Modifier,- ModuleDescriptor.Opens,- ModuleDescriptor.Opens.Modifier,- ModuleDescriptor.Provides,- ModuleDescriptor.Requires,- ModuleDescriptor.Requires.Modifier,- ModuleDescriptor.Version,- ModuleElement.DirectiveKind,- ModuleTree.ModuleKind,- Month,- MonthDay,- MultipleGradientPaint.ColorSpaceType,- MultipleGradientPaint.CycleMethod,- NestingKind,- Normalizer.Form,- NumberFormat.Style,- NumericShaper.Range,- ObjectInputFilter.Status,- ObjectName,- ObjectStreamField,- OffsetDateTime,- OffsetTime,- PeerAddressChangeNotification.AddressChangeEvent,- PKIXReason,- PKIXRevocationChecker.Option,- PosixFilePermission,- ProcessBuilder.Redirect.Type,- Proxy.Type,- PseudoColumnUsage,- QuitStrategy,- Rdn,- RecordingState,- ResolverStyle,- RetentionPolicy,- RoundingMode,- RowFilter.ComparisonType,- RowIdLifetime,- RowSorterEvent.Type,- Runtime.Version,- Short,- ShortBuffer,- SignStyle,- SimpleFileServer.OutputLevel,- Snippet.Kind,- Snippet.Status,- Snippet.SubKind,- SortOrder,- SourceCodeAnalysis.Attribute,- SourceCodeAnalysis.Completeness,- SourceVersion,- SSLEngineResult.HandshakeStatus,- SSLEngineResult.Status,- StackWalker.Option,- StandardCopyOption,- StandardLocation,- StandardNamespace,- StandardOpenOption,- StandardOperation,- StandardProtocolFamily,- String,- StringBuffer,- StringBuilder,- StructuredTaskScope.Subtask.StatePREVIEW,- SwingWorker.StateValue,- System.Logger.Level,- Taglet.Location,- Taskbar.Feature,- Taskbar.State,- TaskEvent.Kind,- TextStyle,- ThaiBuddhistChronology,- ThaiBuddhistDate,- ThaiBuddhistEra,- Thread.State,- Time,- Timestamp,- TimeUnit,- TrayIcon.MessageType,- Tree.Kind,- TypeKind,- URI,- UserSessionEvent.Reason,- UUID,- VarHandle.AccessMode,- VectorShape,- VMOption.Origin,- Window.Type,- XPathEvaluationResult.XPathResultType,- Year,- YearMonth,- ZonedDateTime,- ZoneOffset,- ZoneOffsetTransition,- ZoneOffsetTransitionRule.TimeDefinition
compareTo method is referred to as
 its natural comparison method.
 Lists (and arrays) of objects that implement this interface can be sorted
 automatically by Collections.sort (and
 Arrays.sort).  Objects that implement this
 interface can be used as keys in a sorted map or as
 elements in a sorted set, without the need to
 specify a comparator.
 The natural ordering for a class C is said to be consistent
 with equals if and only if e1.compareTo(e2) == 0 has
 the same boolean value as e1.equals(e2) for every
 e1 and e2 of class C.  Note that null
 is not an instance of any class, and e.compareTo(null) should
 throw a NullPointerException even though e.equals(null)
 returns false.
 It is strongly recommended (though not required) that natural orderings be
 consistent with equals.  This is so because sorted sets (and sorted maps)
 without explicit comparators behave "strangely" when they are used with
 elements (or keys) whose natural ordering is inconsistent with equals.  In
 particular, such a sorted set (or sorted map) violates the general contract
 for set (or map), which is defined in terms of the equals
 method.
 For example, if one adds two keys a and b such that
 (!a.equals(b) && a.compareTo(b) == 0) to a sorted
 set that does not use an explicit comparator, the second add
 operation returns false (and the size of the sorted set does not increase)
 because a and b are equivalent from the sorted set's
 perspective.
 Virtually all Java core classes that implement Comparable
 have natural orderings that are consistent with equals.  One
 exception is BigDecimal, whose natural ordering equates 
 BigDecimal objects with equal numerical values and different
 representations (such as 4.0 and 4.00). For BigDecimal.equals() to return true,
 the representation and numerical value of the two 
 BigDecimal objects must be the same.
For the mathematically inclined, the relation that defines the natural ordering on a given class C is:
       {(x, y) such that x.compareTo(y) <= 0}.
 
       {(x, y) such that x.compareTo(y) == 0}.
 compareTo that the
 quotient is an equivalence relation on C, and that the
 natural ordering is a total order on C.  When we say that a
 class's natural ordering is consistent with equals, we mean that the
 quotient for the natural ordering is the equivalence relation defined by
 the class's equals(Object) method:
     {(x, y) such that x.equals(y)}. 
 In other words, when a class's natural ordering is consistent with
 equals, the equivalence classes defined by the equivalence relation
 of the equals method and the equivalence classes defined by
 the quotient of the compareTo method are the same.
 
This interface is a member of the Java Collections Framework.
- Since:
- 1.2
- See Also:
- 
Method Summary
- 
Method Details- 
compareToCompares this object with the specified object for order. Returns a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object.The implementor must ensure signum(x.compareTo(y)) == -signum(y.compareTo(x))for allxandy. (This implies thatx.compareTo(y)must throw an exception if and only ify.compareTo(x)throws an exception.)The implementor must also ensure that the relation is transitive: (x.compareTo(y) > 0 && y.compareTo(z) > 0)impliesx.compareTo(z) > 0.Finally, the implementor must ensure that x.compareTo(y)==0implies thatsignum(x.compareTo(z)) == signum(y.compareTo(z)), for allz.- API Note:
- It is strongly recommended, but not strictly required that
 (x.compareTo(y)==0) == (x.equals(y)). Generally speaking, any class that implements theComparableinterface and violates this condition should clearly indicate this fact. The recommended language is "Note: this class has a natural ordering that is inconsistent with equals."
- Parameters:
- o- the object to be compared.
- Returns:
- a negative integer, zero, or a positive integer as this object is less than, equal to, or greater than the specified object.
- Throws:
- NullPointerException- if the specified object is null
- ClassCastException- if the specified object's type prevents it from being compared to this object.
 
 
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