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Package java.lang

Core classes including wrappers for primitive types, classes, packages and class loaders, representations of the system, processes, threads and the core exception hierarchy.

See: Description

Interface Summary
Appendable

An Appendable object is one to which a sequence of Unicode characters can be added.

CharSequence General functions on a sequence of chars.
Cloneable This interface should be implemented by classes wishing to support of override Object.clone().
Comparable<T> Interface for objects that can be ordering among other objects.
Iterable<E> This interface is used to indicate that a given class can be iterated over.
Readable A Readable object is simply a source for Unicode character data.
Runnable Runnable is an interface you implement to indicate that your class can be executed as the main part of a Thread, among other places.
Thread.UncaughtExceptionHandler

This interface is used to handle uncaught exceptions which cause a Thread to terminate.

Class Summary
Boolean Instances of class Boolean represent primitive boolean values.
Byte Instances of class Byte represent primitive byte values.
Character Wrapper class for the primitive char data type.
Character.Subset A subset of Unicode blocks.
Character.UnicodeBlock A family of character subsets in the Unicode specification.
Class<T> A Class represents a Java type.
ClassLoader The ClassLoader is a way of customizing the way Java gets its classes and loads them into memory.
Compiler The Compiler class is a placeholder for a JIT compiler implementation, and does nothing unless there is such a compiler.
Double Instances of class Double represent primitive double values.
Enum<T> This class represents a Java enumeration.
Float Instances of class Float represent primitive float values.
InheritableThreadLocal<T> A ThreadLocal whose value is inherited by child Threads.
Integer Instances of class Integer represent primitive int values.
Long Instances of class Long represent primitive long values.
Math Helper class containing useful mathematical functions and constants.
Number Number is a generic superclass of all the numeric classes, including the wrapper classes {@link Byte}, {@link Short}, {@link Integer}, {@link Long}, {@link Float}, and {@link Double}.
Object Object is the ultimate superclass of every class (excepting interfaces).
Package Everything you ever wanted to know about a package.
Process An instance of a subclass of Process is created by the Runtime.exec methods.
ProcessBuilder

This class is used to construct new operating system processes.

Runtime Runtime represents the Virtual Machine.
RuntimePermission A RuntimePermission contains a permission name, but no actions list.
SecurityManager SecurityManager is a class you can extend to create your own Java security policy.
Short Instances of class Short represent primitive short values.
StackTraceElement One function call or stack trace element.
StrictMath Helper class containing useful mathematical functions and constants.
String Strings represent an immutable set of characters.
StringBuffer StringBuffer represents a changeable String.
StringBuilder StringBuilder represents a changeable String.
System System represents system-wide resources; things that represent the general environment.
Thread Thread represents a single thread of execution in the VM.
ThreadGroup ThreadGroup allows you to group Threads together.
ThreadLocal<T> ThreadLocal objects have a different state associated with every Thread that accesses them.
Thread.State

Represents the current state of a thread, according to the VM rather than the operating system.

Throwable Throwable is the superclass of all exceptions that can be raised.
Void Void is a placeholder class so that the variable Void.TYPE (also available as void.class) can be supported for reflection return types.
Exception Summary
ArithmeticException Thrown when a math error has occured, such as trying to divide an integer by zero.
ArrayIndexOutOfBoundsException Thrown when attempting to access a position outside the valid range of an array.
ArrayStoreException Thrown when trying to store an object of the wrong runtime type in an array.
ClassCastException Thrown when an attempt is made to cast an object which is not of the appropriate runtime type.
ClassNotFoundException Thrown when a class is requested by reflection, but the class definition cannot be found.
CloneNotSupportedException Thrown to indicate an object should not or could not be cloned.
EnumConstantNotPresentException An exception of this type is thrown when a symbolic reference is made to an enum constant which does not exist.
Exception The root class of all exceptions worth catching in a program.
IllegalAccessException Thrown whenever a reflective method tries to do something that the compiler would not allow.
IllegalArgumentException Thrown when a method is passed an illegal or inappropriate argument.
IllegalMonitorStateException Thrown when a thread attempts to wait or notify on a monitor that it does not own (ie. it has not synchronized on the object).
IllegalStateException Thrown when a method is invoked at an illegal or inappropriate time.
IllegalThreadStateException Thrown When trying to manipulate a Thread which is in an inappropriate state.
IndexOutOfBoundsException This exception can be thrown to indicate an attempt to access an index which is out of bounds on objects like String, Array, or Vector.
InstantiationException Thrown when an attempt is made to use reflection to build a non-instantiable class (an interface or abstract class).
InterruptedException Thrown when a thread interrupts another thread which was previously sleeping, waiting, or paused in some other way.
NegativeArraySizeException Thrown when an attempt is made to create an array with a negative size.
NoSuchFieldException Thrown to indicate the class does not have the specified field.
NoSuchMethodException Thrown to indicate the class does not have the specified method.
NullPointerException Thrown when attempting to use null where an object is required.
NumberFormatException Can be thrown when attempting to convert a String to one of the numeric types, but the operation fails because the string has the wrong format.
RuntimeException All exceptions which are subclasses of RuntimeException can be thrown at any time during the execution of a Java virtual machine.
SecurityException The security manager will throw this exception to indicate a security violation.
StringIndexOutOfBoundsException This exception can be thrown to indicate an attempt to access an index which is out of bounds of a String.
TypeNotPresentException

Thrown when a type is accessed using a String-based representation, but no definition of the supplied type is found.

UnsupportedOperationException This exception is thrown by an object when an operation is requested of it that it does not support.
Error Summary
AbstractMethodError An AbstractMethodError is thrown when an application attempts to access an abstract method.
AssertionError An assertion error normally occurs as a result of the assert statement added in JDK 1.4, to indicate that an assertion failed.
ClassCircularityError A ClassCircularityError is thrown when a circular dependency has been detected while initializing a class.
ClassFormatError A ClassFormatError is thrown when a Java Virtual Machine unable to read a class file because the file is corrupted or cannot be interpreted as a class file.
Error Applications should not try to catch errors since they indicate abnormal conditions.
ExceptionInInitializerError An ExceptionInInitializerError is thrown when an uncaught exception has occurred in a static initializer or the initializer for a static variable.
IllegalAccessError An IllegalAccessError is thrown when an attempt is made to call a method, or access or modify a field that the application does not have access to.
IncompatibleClassChangeError An IncompatibleClassChangeError is thrown when the definition of a class used by the currently executing method has changed in an incompatible way.
InstantiationError An InstantiationError is thrown when an attempt is made to create an instance of an abstract class or an interface.
InternalError An InternalError is thrown when a mystical error has occurred in the Java Virtual Machine.
LinkageError Subclasses of LinkageError are thrown to indicate that two classes which were compatible at separate compilation times cannot be linked to one another.
NoClassDefFoundError A NoClassDefFoundError is thrown when a classloader or the Java Virtual Machine tries to load a class and no definition of the class can be found.
NoSuchFieldError A NoSuchFieldError is thrown if an application attempts to access a field of a class, and that class no longer has that field.
NoSuchMethodError A NoSuchMethodError is thrown if an application attempts to access a method of a class, and that class no longer has that method.
OutOfMemoryError Thrown when the Java Virtual Machine is unable to allocate an object because it is out of memory and no more memory could be made available by the garbage collector.
StackOverflowError A StackOverflowError is thrown when the execution stack overflow occurs.
ThreadDeath ThreadDeath is thrown in a thread when someone calls stop() on that thread.
UnknownError An UnknownError is thrown when a serious but unknown problem has occurred in the Java Virtual Machine.
UnsatisfiedLinkError A UnsatisfiedLinkError is thrown if an appropriate native language definition of a method declared native cannot be found by the Java Virtual Machine.
UnsupportedClassVersionError An UnsupportedClassVersionError is thrown when the Java Virtual Machine determines it does not support the major and minor version numbers in the class file it is attempting to read.
VerifyError A VerifyError is thrown if there is a security problem or internal inconsistency in a class file as detected by the "verifier."
VirtualMachineError A VirtualMachineError or its subclasses are thrown to indicate there is something wrong with the Java Virtual Machine or that it does not have the resources needed for it to continue execution.

Package java.lang Description:

Core classes including wrappers for primitive types, classes, packages and class loaders, representations of the system, processes, threads and the core exception hierarchy.

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