Module java.base

Package java.lang

Provides classes that are fundamental to the design of the Java programming language. The most important classes are Object, which is the root of the class hierarchy, and Class, instances of which represent classes at run time.

Frequently it is necessary to represent a value of primitive type as if it were an object. The wrapper classesBoolean,Character,Integer,Long,Float, andDouble serve this purpose. An object of type Double, for example, contains a field whose type is double, representing that value in such a way that a reference to it can be stored in a variable of reference type. These classes also provide a number of methods for converting among primitive values, as well as supporting such standard methods as equals and hashCode. TheVoid class is a non-instantiable class that holds a reference to aClass object representing the type void.

The classMath provides commonly used mathematical functions such as sine, cosine, and square root. The classes String,StringBuffer, andStringBuilder similarly provide commonly used operations on character strings.

ClassesClassLoader,Process, ProcessBuilder,Runtime,SecurityManager, andSystem provide "system operations" that manage the dynamic loading of classes, creation of external processes, host environment inquiries such as the time of day, and enforcement of security policies.

ClassThrowable encompasses objects that may be thrown by thethrow statement. Subclasses ofThrowable represent errors and exceptions.

Character Encodings

The specification of thejava.nio.charset.Charset class describes the naming conventions for character encodings as well as the set of standard encodings that must be supported by every implementation of the Java platform.

Since:: 1.0

Interface Summary
Interface	Description
Appendable	An object to which`char` sequences and values can be appended.
AutoCloseable	An object that may hold resources (such as file or socket handles) until it is closed.
CharSequence	A`CharSequence` is a readable sequence of`char` values.
Cloneable	A class implements the`Cloneable` interface to indicate to the`Object.clone()` method that it is legal for that method to make a field-for-field copy of instances of that class.
Comparable<T>	This interface imposes a total ordering on the objects of each class that implements it.
Iterable<T>	Implementing this interface allows an object to be the target of the enhanced`for` statement (sometimes called the "for-each loop" statement).
ProcessHandle	ProcessHandle identifies and provides control of native processes.
ProcessHandle.Info	Information snapshot about the process.
Readable	A`Readable` is a source of characters.
Runnable	The`Runnable` interface should be implemented by any class whose instances are intended to be executed by a thread.
StackWalker.StackFrame	A`StackFrame` object represents a method invocation returned by`StackWalker`.
System.Logger	`System.Logger` instances log messages that will be routed to the underlying logging framework the`LoggerFinder` uses.
Thread.UncaughtExceptionHandler	Interface for handlers invoked when a`Thread` abruptly terminates due to an uncaught exception.

Class Summary
Class	Description
Boolean	The Boolean class wraps a value of the primitive type`boolean` in an object.
Byte	The`Byte` class wraps a value of primitive type`byte` in an object.
Character	The`Character` class wraps a value of the primitive type`char` in an object.
Character.Subset	Instances of this class represent particular subsets of the Unicode character set.
Character.UnicodeBlock	A family of character subsets representing the character blocks in the Unicode specification.
Class<T>	Instances of the class`Class` represent classes and interfaces in a running Java application.
ClassLoader	A class loader is an object that is responsible for loading classes.
ClassValue<T>	Lazily associate a computed value with (potentially) every type.
Compiler	Deprecated, for removal: This API element is subject to removal in a future version. JIT compilers and their technologies vary too widely to be controlled effectively by a standardized interface.
Double	The`Double` class wraps a value of the primitive type`double` in an object.
Enum<E extendsEnum<E>>	This is the common base class of all Java language enumeration types.
Enum.EnumDesc<E extendsEnum<E>>	Anominal descriptor for an`enum` constant.
Float	The`Float` class wraps a value of primitive type`float` in an object.
InheritableThreadLocal<T>	This class extends`ThreadLocal` to provide inheritance of values from parent thread to child thread: when a child thread is created, the child receives initial values for all inheritable thread-local variables for which the parent has values.
Integer	The`Integer` class wraps a value of the primitive type`int` in an object.
Long	The`Long` class wraps a value of the primitive type `long` in an object.
Math	The class`Math` contains methods for performing basic numeric operations such as the elementary exponential, logarithm, square root, and trigonometric functions.
Module	Represents a run-time module, either`named` or unnamed.
ModuleLayer	A layer of modules in the Java virtual machine.
ModuleLayer.Controller	Controls a module layer.
Number	The abstract class`Number` is the superclass of platform classes representing numeric values that are convertible to the primitive types`byte`,`double`,`float`, `int`,`long`, and`short`.
Object	Class`Object` is the root of the class hierarchy.
Package	Represents metadata about a run-time package associated with a class loader.
Process	`Process` provides control of native processes started by ProcessBuilder.start and Runtime.exec.
ProcessBuilder	This class is used to create operating system processes.
ProcessBuilder.Redirect	Represents a source of subprocess input or a destination of subprocess output.
Runtime	Every Java application has a single instance of class`Runtime` that allows the application to interface with the environment in which the application is running.
Runtime.Version	A representation of a version string for an implementation of the Java SE Platform.
RuntimePermission	This class is for runtime permissions.
SecurityManager	The security manager is a class that allows applications to implement a security policy.
Short	The`Short` class wraps a value of primitive type `short` in an object.
StackTraceElement	An element in a stack trace, as returned by`Throwable.getStackTrace()`.
StackWalker	A stack walker.
StrictMath	The class`StrictMath` contains methods for performing basic numeric operations such as the elementary exponential, logarithm, square root, and trigonometric functions.
String	The`String` class represents character strings.
StringBuffer	A thread-safe, mutable sequence of characters.
StringBuilder	A mutable sequence of characters.
System	The`System` class contains several useful class fields and methods.
System.LoggerFinder	The`LoggerFinder` service is responsible for creating, managing, and configuring loggers to the underlying framework it uses.
Thread	Athread is a thread of execution in a program.
ThreadGroup	A thread group represents a set of threads.
ThreadLocal<T>	This class provides thread-local variables.
Throwable	The`Throwable` class is the superclass of all errors and exceptions in the Java language.
Void	The`Void` class is an uninstantiable placeholder class to hold a reference to the`Class` object representing the Java keyword void.

Enum Summary
Enum	Description
Character.UnicodeScript	A family of character subsets representing the character scripts defined in theUnicode Standard Annex #24: Script Names.
ProcessBuilder.Redirect.Type	The type of a`ProcessBuilder.Redirect`.
StackWalker.Option	Stack walker option to configure thestack frame information obtained by a`StackWalker`.
System.Logger.Level	Systemloggers levels.
Thread.State	A thread state.

Exception Summary
Exception	Description
ArithmeticException	Thrown when an exceptional arithmetic condition has occurred.
ArrayIndexOutOfBoundsException	Thrown to indicate that an array has been accessed with an illegal index.
ArrayStoreException	Thrown to indicate that an attempt has been made to store the wrong type of object into an array of objects.
ClassCastException	Thrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance.
ClassNotFoundException	Thrown when an application tries to load in a class through its string name using: The`forName` method in class`Class`.
CloneNotSupportedException	Thrown to indicate that the`clone` method in class`Object` has been called to clone an object, but that the object's class does not implement the`Cloneable` interface.
EnumConstantNotPresentException	Thrown when an application tries to access an enum constant by name and the enum type contains no constant with the specified name.
Exception	The class`Exception` and its subclasses are a form of`Throwable` that indicates conditions that a reasonable application might want to catch.
IllegalAccessException	An IllegalAccessException is thrown when an application tries to reflectively create an instance (other than an array), set or get a field, or invoke a method, but the currently executing method does not have access to the definition of the specified class, field, method or constructor.
IllegalArgumentException	Thrown to indicate that a method has been passed an illegal or inappropriate argument.
IllegalCallerException	Thrown to indicate that a method has been called by an inappropriate caller.
IllegalMonitorStateException	Thrown to indicate that a thread has attempted to wait on an object's monitor or to notify other threads waiting on an object's monitor without owning the specified monitor.
IllegalStateException	Signals that a method has been invoked at an illegal or inappropriate time.
IllegalThreadStateException	Thrown to indicate that a thread is not in an appropriate state for the requested operation.
IndexOutOfBoundsException	Thrown to indicate that an index of some sort (such as to an array, to a string, or to a vector) is out of range.
InstantiationException	Thrown when an application tries to create an instance of a class using the`newInstance` method in class`Class`, but the specified class object cannot be instantiated.
InterruptedException	Thrown when a thread is waiting, sleeping, or otherwise occupied, and the thread is interrupted, either before or during the activity.
LayerInstantiationException	Thrown when creating amodule layer fails.
NegativeArraySizeException	Thrown if an application tries to create an array with negative size.
NoSuchFieldException	Signals that the class doesn't have a field of a specified name.
NoSuchMethodException	Thrown when a particular method cannot be found.
NullPointerException	Thrown when an application attempts to use`null` in a case where an object is required.
NumberFormatException	Thrown to indicate that the application has attempted to convert a string to one of the numeric types, but that the string does not have the appropriate format.
ReflectiveOperationException	Common superclass of exceptions thrown by reflective operations in core reflection.
RuntimeException	`RuntimeException` is the superclass of those exceptions that can be thrown during the normal operation of the Java Virtual Machine.
SecurityException	Thrown by the security manager to indicate a security violation.
StringIndexOutOfBoundsException	Thrown by`String` methods to indicate that an index is either negative or greater than the size of the string.
TypeNotPresentException	Thrown when an application tries to access a type using a string representing the type's name, but no definition for the type with the specified name can be found.
UnsupportedOperationException	Thrown to indicate that the requested operation is not supported.

Error Summary
Error	Description
AbstractMethodError	Thrown when an application tries to call an abstract method.
AssertionError	Thrown to indicate that an assertion has failed.
BootstrapMethodError	Thrown to indicate that an`invokedynamic` instruction or a dynamic constant failed to resolve its bootstrap method and arguments, or for`invokedynamic` instruction the bootstrap method has failed to provide acall site with atarget of the correctmethod type, or for a dynamic constant the bootstrap method has failed to provide a constant value of the required type.
ClassCircularityError	Thrown when the Java Virtual Machine detects a circularity in the superclass hierarchy of a class being loaded.
ClassFormatError	Thrown when the Java Virtual Machine attempts to read a class file and determines that the file is malformed or otherwise cannot be interpreted as a class file.
Error	An`Error` is a subclass of`Throwable` that indicates serious problems that a reasonable application should not try to catch.
ExceptionInInitializerError	Signals that an unexpected exception has occurred in a static initializer.
IllegalAccessError	Thrown if an application attempts to access or modify a field, or to call a method that it does not have access to.
IncompatibleClassChangeError	Thrown when an incompatible class change has occurred to some class definition.
InstantiationError	Thrown when an application tries to use the Java`new` construct to instantiate an abstract class or an interface.
InternalError	Thrown to indicate some unexpected internal error has occurred in the Java Virtual Machine.
LinkageError	Subclasses of`LinkageError` indicate that a class has some dependency on another class; however, the latter class has incompatibly changed after the compilation of the former class.
NoClassDefFoundError	Thrown if the Java Virtual Machine or a`ClassLoader` instance tries to load in the definition of a class (as part of a normal method call or as part of creating a new instance using the`new` expression) and no definition of the class could be found.
NoSuchFieldError	Thrown if an application tries to access or modify a specified field of an object, and that object no longer has that field.
NoSuchMethodError	Thrown if an application tries to call a specified method of a class (either static or instance), and that class no longer has a definition of that method.
OutOfMemoryError	Thrown when the Java Virtual Machine cannot allocate an object because it is out of memory, and no more memory could be made available by the garbage collector.
StackOverflowError	Thrown when a stack overflow occurs because an application recurses too deeply.
ThreadDeath	An instance of`ThreadDeath` is thrown in the victim thread when the (deprecated)`Thread.stop()` method is invoked.
UnknownError	Thrown when an unknown but serious exception has occurred in the Java Virtual Machine.
UnsatisfiedLinkError	Thrown if the Java Virtual Machine cannot find an appropriate native-language definition of a method declared`native`.
UnsupportedClassVersionError	Thrown when the Java Virtual Machine attempts to read a class file and determines that the major and minor version numbers in the file are not supported.
VerifyError	Thrown when the "verifier" detects that a class file, though well formed, contains some sort of internal inconsistency or security problem.
VirtualMachineError	Thrown to indicate that the Java Virtual Machine is broken or has run out of resources necessary for it to continue operating.

Annotation Types Summary
Annotation Type	Description
Deprecated	A program element annotated`@Deprecated` is one that programmers are discouraged from using.
FunctionalInterface	An informative annotation type used to indicate that an interface type declaration is intended to be afunctional interface as defined by the Java Language Specification.
Override	Indicates that a method declaration is intended to override a method declaration in a supertype.
SafeVarargs	A programmer assertion that the body of the annotated method or constructor does not perform potentially unsafe operations on its varargs parameter.
SuppressWarnings	Indicates that the named compiler warnings should be suppressed in the annotated element (and in all program elements contained in the annotated element).

Movatterモバイル変換

Package java.lang

Character Encodings