Package java.lang

Provides classes that are fundamental to the design of the Java programming language.

See:
Description

Interface Summary

Appendable	An object to which char sequences and values can be appended.
CharSequence	CharSequence is an interface that provides a read-only access to a sequence of characters.
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 "foreach" statement.
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.
Thread.UncaughtExceptionHandler	Interface for handler of uncaught exception.

Class Summary

Boolean	The Boolean class wraps a value of the primitive type boolean in an object.
Byte	Byte provides a class for byte values stored in objects.
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>	Class whose instances represent Java classes.
ClassLoader	ClassLoader provides a new name space for classes that are loaded into the system from an external source.
Compiler	Compiler represents a JIT compiler implementation.
Double	The Double class wraps a value of the primitive type double in an object.
Enum<E extends Enum<E>>	Enum provides the abstract super class for all JDK 1.5 enumeration types.
Float	The Float class wraps a value of primitive type float in an object.
InheritableThreadLocal<T>	InheritableThreadLocal provides thread local variables that inherit their default value from the parent thread.
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.
Number	Number super class of classes that impelement number, i.e., Byte, Short, Integer, Double, Long, BigInteger, etc.
Object	Object is the base class for all classes in Java.
Package	Package objects contain version information about the implementation and specification of a Java package.
Process	The ProcessBuilder.start() and Runtime.exec methods create a native process and return an instance of a subclass of Process that can be used to control the process and obtain information about it.
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	Runtime provides control over the runtime system, i.e., memory management, VM termination cleanup, execution of external commands, etc.
RuntimePermission	This class is for runtime permissions.
SecurityManager	The security manager is a class that allows applications to implement a security policy.
Short	Short provides a class for short values stored in objects.
StackTraceElement	StackTraceElement class that represents an entry in a stack trace, e.g., the stack trace of an exception.
StrictMath	The class StrictMath contains methods for performing basic numeric operations such as the elementary exponential, logarithm, square root, and trigonometric functions.
String	String represents immutable strings of (16-bit) unicode characters.
StringBuffer	A thread-safe, mutable sequence of characters.
StringBuilder	A mutable sequence of characters.
System	System contains static fields and methods that permit access to properties of the current environment.
Thread	Class that represents Java threads.
ThreadGroup	ThreadGroup enables grouping of threads and modifying a whole group of threads.
ThreadLocal<T>	ThreadLocal provides thread local variables, i.e., variables for which each thread that uses them has its own private copy.
Throwable	Throwable is the root class of all classes whose instances may be thrown as exceptions.
Void	Void provides a representation for the pseudo-type "void" used for methods that do not return a result.

Enum Summary

ProcessBuilder.Redirect.Type	The type of a ProcessBuilder.Redirect.
Thread.State	JDK 1.5 thread State

Exception Summary

ArithmeticException	ArithmeticException is thrown when an attempt is made to perform a integer or long devision with a divisor of 0.
ArrayIndexOutOfBoundsException	ArrayIndexOutOfBoundsException is thrown when an attempt is made to access an array element with an index that is negative or larger or equal than the array length.
ArrayStoreException	ArrayStoreException is thrown when an attempt is made to store a reference into an array that has an incompatible runtime element type.
ClassCastException	ClassCastException is a runtime exception thrown when an attempt is made to cast a reference to a type the referenced instance is not an instance of.
ClassNotFoundException	ClassNotFoundException is thrown by methods such as Class.forName() if an attempt to load a class failed.
CloneNotSupportedException	CloneNotSupportedException is thrown on an attempt to execute Object.clone() on an object that does not implement the Cloneable interface.
EnumConstantNotPresentException	EnumConstantNotPresentException is thrown when an attempt is made to access an enum element by name and such an element does not exist.
Exception	Exception is a base class for flagged exceptions.
IllegalAccessException	IllegalAccessException is thrown by reflection code if an attempt is made to access a field or a method or to create an instance from an environment that is not permitted to perform this access.
IllegalArgumentException	IllegalArgumentException is thrown when a method is called with an illegal argument value.
IllegalMonitorStateException	IllegalMonitorStateException is thrown when an attempt is made to call wait or notify on an object without owning the monitor assiciated with this object.
IllegalStateException	IllegalStateException is a runtime exception that is thrown when a method is called at an inapropriate time, e.g.
IllegalThreadStateException	IllegalThreadStateException is thrown by methods of class Thread if these methods are called on a thread that is not in a state that would permit calling these methods.
IndexOutOfBoundsException	IndexOutOfBoundsException is thrown when an attempt is made to use an index that is outside of the permitted range for the accessed object.
InstantiationException	InstantiationException is thrown when an attempt is made to instanciate an object via reflection without having the required access rights for the instantiation.
InterruptedException	InterruptedException is thrown when a thread is interrupted by another thread during a wait() or within asynchronously interruptible code.
NegativeArraySizeException	NegativeArraySizeException is a runtime exception that is thrown by the virtual machine if an attempt is made to create an instance of an array with a negative size.
NoSuchFieldException	NoSuchFieldException is thrown by reflection methods if a field is not found in a given class.
NoSuchMethodException	NoSuchMethodException is thrown by reflection methods if a method is not found in a given class.
NullPointerException	NullPointerException is a runtime exception that is thrown by the virtual machine on an attempt to dereference the value null.
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.
RuntimeException	This is the base-class of all unchecked exceptions.
SecurityException	SecurityException is a runtime exception thrown by a security manager if a requested permission is not granted.
StringIndexOutOfBoundsException	StringIndexOutOfBoundsException is a runtime exception that is thrown on an attempt to access a character of a string with at an invalid index.
TypeNotPresentException	TypeNotPresentException is a runtime exception that is thrown when a type given as a string could not be loaded or created.
UnsupportedOperationException	UnsupportedOperationException is a runtime exception that may be thrown by a method that is not permitted, e.g., an abstract method that is implemented to permit compilation, but it is not supported by the implementation.

Error Summary

AbstractMethodError	AbstractMethodError is an error thrown on a virtual or interface call to a method that is not implemented by the target instance due to a change in the super class that added a new abstract method.
AssertionError	An AssertionError represents an assertion that failed.
ClassCircularityError	ClassCircularityError is a linkage error that is thrown when an inheritance circularity is found when loading a class.
ClassFormatError	ClassFormatError is a linkage error that is thrown when an a class could not be loaded since it does not respect the class file format.
Error	Sub-classes of Error describe abnormal exceptional states within the virtual machine or application.
ExceptionInInitializerError	An ExceptionInInitializerError is generated if an unhandled exception occurred in a static initializer of a class.
IllegalAccessError	IllegalAccessError is thrown by the virtual machine if an attempt is made to call a method or access a field whose access rights have changed such that the access is illegal now.
IncompatibleClassChangeError	IncompatibleClassChangeError is thrown by the virtual machine if a class C uses another class D and C was compiled against a different version of a D' of D that is incompatible.
InstantiationError	InstantiationError is an IncompatibleClassChangeError that is thrown by the VM if an attempt is made to instantiate an object of a class without having the required access rights (e.g., the constructor is private).
InternalError	InternalError is a super class for severe error conditions in the system, e.g.
LinkageError	LinkageError is thrown if linking of a class failed, i.e., another class that is needed by this class is missing or does not declare a field or method that is required.
NoClassDefFoundError	NoClassDefFoundError is a linkage error that is thrown by the virtual machine if linking of a class failed since another class could not be loaded.
NoSuchFieldError	NoSuchFieldError is a linkage error that is thrown by the virtual machine if linking of a class failed since a referenced field is not found.
NoSuchMethodError	NoSuchMethodError is a linkage error that is thrown by the virtual machine if linking of a class failed since a referenced method is not found.
OutOfMemoryError	An OutOfMemoryException is a signal from the virtual machine that a memory allocation has failed because not enough free memory was available.
StackOverflowError	StackOverflowError is a virtual machine error that is thrown by the virtual machine if a thread's runtime stack overflows due to a too deep nesting of method calls.
ThreadDeath	ThreadDeath is thrown in a stopped thread when Thread.stop() is called on this thread.
UnknownError	UnknownError is a virtual machine error that is thrown by the virtual machine if an error of unknown origin occurred.
UnsatisfiedLinkError	UnsatisfiedLinkError is a linkage error that is thrown by the virtual machine if the implementation of a native function could not be found.
UnsupportedClassVersionError	UnsupportedClassVersionError is a linkage error that is thrown by the virtual machine if an attempt is made to load a class with a class file version that is not supported by the virtual machine.
VerifyError	VerifyError is a linkage error that is thrown if class file verification failed.
VirtualMachineError	VirtualMachineError is a super class for error conditions that originate in the virtual machine, such as out of memory or class loading and linking problems.

Annotation Types Summary

Deprecated	A program element annotated @Deprecated is one that programmers are discouraged from using, typically because it is dangerous, or because a better alternative exists.
Override	Indicates that a method declaration is intended to override a method declaration in a supertype.
SuppressWarnings	Indicates that the named compiler warnings should be suppressed in the annotated element (and in all program elements contained in the annotated element).

Package java.lang Description

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 classes Boolean, Character, Integer, Long, Float, and Double 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. The Void class is a non-instantiable class that holds a reference to a Class object representing the type void.

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

Classes ClassLoader, Process, ProcessBuilder, Runtime, SecurityManager, and System 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.

Class Throwable encompasses objects that may be thrown by the throw statement. Subclasses of Throwable represent errors and exceptions.

Character Encodings

The specification of the java.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:

JDK1.0