Package java.lang

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

See: Description

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 "for-each loop" statement.
Runnable	The Runnable interface should be implemented by any class whose instances are intended to be executed by a thread.

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.
Class<T>	Instances of the class Class represent classes and interfaces in a running Java application.
Double	The Double class wraps a value of the primitive type double in an object.
Enum<E extends Enum<E>>	This is the common base class of all Java language enumeration types.
Float	The Float class wraps a value of primitive type float in an object.
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	The abstract class Number is the superclass of Byte, Double, Float, Integer, Long, and Short.
Object	Class Object is the root of the class hierarchy.
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.
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.
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.
Thread	A thread is a thread of execution in a program.
Throwable	The Throwable class is the superclass of all errors and exceptions in the Java language.

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.
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 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.
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.
NegativeArraySizeException	Thrown if an application tries to create an array with negative size.
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.
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.
UnsupportedOperationException	Thrown to indicate that the requested operation is not supported.

Error Summary

Error	Description
AssertionError	Thrown to indicate that an assertion has failed.
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.
IncompatibleClassChangeError	Thrown when an incompatible class change has occurred to some class definition.
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 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.
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.
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.
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, 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 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.

Since:

JDK1.0