java.lang Package

java.lang Package : Provides classes that are fundamental to the design of the Java programming language.

Interfaces in java.lang Package

S.No Interface & Description
1 Appendable

An object to which char sequences and values can be appended.
2 AutoCloseable

An object that may hold resources (such as file or socket handles) until it is closed.
3 CharSequence

A CharSequence is a readable sequence of char values.
4 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.
5 Comparable<T>

This interface imposes a total ordering on the objects of each class that implements it.
6 Iterable<T>

Implementing this interface allows an object to be the target of the "for-each loop" statement.
7 Readable

A Readable is a source of characters.
8 Runnable

The Runnable interface should be implemented by any class whose instances are intended to be executed by a thread.
9 Thread.UncaughtExceptionHandler

Interface for handlers invoked when a Thread abruptly terminates due to an uncaught exception.

Classes in java.lang Package

S.No Class & Description
1 Boolean

The Boolean class wraps a value of the primitive type boolean in an object.
2 Byte

The Byte class wraps a value of primitive type byte in an object.
3 Character

The Character class wraps a value of the primitive type char in an object.
4 Character.Subset

Instances of this class represent particular subsets of the Unicode character set.
5 Character.UnicodeBlock

A family of character subsets representing the character blocks in the Unicode specification.
6 Class<T>

Instances of the class Class represent classes and interfaces in a running Java application.
7 ClassLoader

A class loader is an object that is responsible for loading classes.
8 ClassValue<T>

Lazily associate a computed value with (potentially) every type.
9 Compiler

The Compiler class is provided to support Java-to-native-code compilers and related services.
10 Double

The Double class wraps a value of the primitive type double in an object.
11 Enum<E extends Enum<E>>

This is the common base class of all Java language enumeration types.
12 Float

The Float class wraps a value of primitive type float in an object.
13 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.
14 Integer

The Integer class wraps a value of the primitive type int in an object.
15 Long

The Long class wraps a value of the primitive type long in an object.
16 Math

The class Math contains methods for performing basic numeric operations such as the elementary exponential, logarithm, square root, and trigonometric functions.
17 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.
18 Object

Class Object is the root of the class hierarchy.
19 Package

Package objects contain version information about the implementation and specification of a Java package.
20 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.
21 ProcessBuilder

This class is used to create operating system processes.
22 ProcessBuilder.Redirect

Represents a source of subprocess input or a destination of subprocess output.
23 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.
24 RuntimePermission

This class is for runtime permissions.
25 SecurityManager

The security manager is a class that allows applications to implement a security policy.
26 Short

The Short class wraps a value of primitive type short in an object.
27 StackTraceElement

An element in a stack trace, as returned by Throwable.getStackTrace().
28 StrictMath

The class StrictMath contains methods for performing basic numeric operations such as the elementary exponential, logarithm, square root, and trigonometric functions.
29 String

The String class represents character strings.
30 StringBuffer

A thread-safe, mutable sequence of characters.
31 StringBuilder

A mutable sequence of characters.
32 System

The System class contains several useful class fields and methods.
33 Thread

A thread is a thread of execution in a program.
34 ThreadGroup

A thread group represents a set of threads.
35 ThreadLocal<T>

This class provides thread-local variables.
36 Throwable

The Throwable class is the superclass of all errors and exceptions in the Java language.
37 Void

The Void class is an uninstantiable placeholder class to hold a reference to the Class object representing the Java keyword void.

Enums in java.lang Package

S.No Enum & Description
1 Character.UnicodeScript

A family of character subsets representing the character scripts defined in the Unicode Standard Annex #24: Script Names.
2 ProcessBuilder.Redirect.Type

The type of a ProcessBuilder.Redirect.
3 Thread.State

A thread state.

Exception Classes in java.lang Package

S.No Exception Class & Description
1 ArithmeticException

Thrown when an exceptional arithmetic condition has occurred.
2 ArrayIndexOutOfBoundsException

Thrown to indicate that an array has been accessed with an illegal index.
3 ArrayStoreException

Thrown to indicate that an attempt has been made to store the wrong type of object into an array of objects.
4 ClassCastException

Thrown to indicate that the code has attempted to cast an object to a subclass of which it is not an instance.
5 ClassNotFoundException

Thrown when an application tries to load in a class through its string name using: The forName method in class Class.
6 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.
7 EnumConstantNotPresentException

Thrown when an application tries to access an enum constant by name and the enum type contains no constant with the specified name.
8 Exception

The class Exception and its subclasses are a form of Throwable that indicates conditions that a reasonable application might want to catch.
9 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.
10 IllegalArgumentException

Thrown to indicate that a method has been passed an illegal or inappropriate argument.
11 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.
12 IllegalStateException

Signals that a method has been invoked at an illegal or inappropriate time.
13 IllegalThreadStateException

Thrown to indicate that a thread is not in an appropriate state for the requested operation.
14 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.
15 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.
16 InterruptedException

Thrown when a thread is waiting, sleeping, or otherwise occupied, and the thread is interrupted, either before or during the activity.
17 NegativeArraySizeException

Thrown if an application tries to create an array with negative size.
18 NoSuchFieldException

Signals that the class doesn’t have a field of a specified name.
19 NoSuchMethodException

Thrown when a particular method cannot be found.
20 NullPointerException

Thrown when an application attempts to use null in a case where an object is required.
21 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.
22 ReflectiveOperationException

Common superclass of exceptions thrown by reflective operations in core reflection.
23 RuntimeException

RuntimeException is the superclass of those exceptions that can be thrown during the normal operation of the Java Virtual Machine.
24 SecurityException

Thrown by the security manager to indicate a security violation.
25 StringIndexOutOfBoundsException

Thrown by String methods to indicate that an index is either negative or greater than the size of the string.
26 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.
27 UnsupportedOperationException

Thrown to indicate that the requested operation is not supported.

Error Classes in java.lang Package

S.No Error Class & Description
1 AbstractMethodError

Thrown when an application tries to call an abstract method.
2 AssertionError

Thrown to indicate that an assertion has failed.
3 BootstrapMethodError

Thrown to indicate that an invokedynamic instruction has failed to find its bootstrap method, or the bootstrap method has failed to provide a call site with a target of the correct method type.
4 ClassCircularityError

Thrown when the Java Virtual Machine detects a circularity in the superclass hierarchy of a class being loaded.
5 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.
6 Error

An Error is a subclass of Throwable that indicates serious problems that a reasonable application should not try to catch.
7 ExceptionInInitializerError

Signals that an unexpected exception has occurred in a static initializer.
8 IllegalAccessError

Thrown if an application attempts to access or modify a field, or to call a method that it does not have access to.
9 IncompatibleClassChangeError

Thrown when an incompatible class change has occurred to some class definition.
10 InstantiationError

Thrown when an application tries to use the Java new construct to instantiate an abstract class or an interface.
11 InternalError

Thrown to indicate some unexpected internal error has occurred in the Java Virtual Machine.
12 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.
13 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.
14 NoSuchFieldError

Thrown if an application tries to access or modify a specified field of an object, and that object no longer has that field.
15 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.
16 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.
17 StackOverflowError

Thrown when a stack overflow occurs because an application recurses too deeply.
18 ThreadDeath

An instance of ThreadDeath is thrown in the victim thread when the (deprecated) Thread.stop() method is invoked.
19 UnknownError

Thrown when an unknown but serious exception has occurred in the Java Virtual Machine.
20 UnsatisfiedLinkError

Thrown if the Java Virtual Machine cannot find an appropriate native-language definition of a method declared native.
21 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.
22 VerifyError

Thrown when the "verifier" detects that a class file, though well formed, contains some sort of internal inconsistency or security problem.
23 VirtualMachineError

Thrown to indicate that the Java Virtual Machine is broken or has run out of resources necessary for it to continue operating.

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