Since: API Level 1
package

java.lang

Interfaces

AppendableDeclares methods to append characters or character sequences. 
CharSequenceThis interface represents an ordered set of characters and defines the methods to probe them. 
CloneableThis (empty) interface must be implemented by all classes that wish to support cloning. 
Comparable<T>This interface should be implemented by all classes that wish to define a natural order of their instances. 
Iterable<T>Instances of classes that implement this interface can be used with the enhanced for loop. 
ReadableRepresents a sequence of characters that can be incrementally read (copied) into a CharBuffer
RunnableRepresents a command that can be executed. 
Thread.UncaughtExceptionHandlerImplemented by objects that want to handle cases where a thread is being terminated by an uncaught exception. 

Classes

BooleanThe wrapper for the primitive type boolean
ByteThe wrapper for the primitive type byte
CharacterThe wrapper for the primitive type char
Character.Subset 
Character.UnicodeBlockRepresents a block of Unicode characters, as defined by the Unicode 4.0.1 specification. 
Class<T>The in-memory representation of a Java class. 
ClassLoaderLoads classes and resources from a repository. 
CompilerPlaceholder class for environments which explicitly manage the action of a Just In Time (JIT) compiler. 
DoubleThe wrapper for the primitive type double
Enum<E extends Enum<E>>The superclass of all enumerated types. 
FloatThe wrapper for the primitive type float
InheritableThreadLocal<T>A thread-local variable whose value is passed from parent to child thread. 
IntegerThe wrapper for the primitive type int
LongThe wrapper for the primitive type long
MathClass Math provides basic math constants and operations such as trigonometric functions, hyperbolic functions, exponential, logarithms, etc. 
NumberThe abstract superclass of the classes which represent numeric base types (that is Byte, Short, Integer, Long, Float, and Double
ObjectThe root class of the Java class hierarchy. 
PackageContains information about a Java package. 
ProcessRepresents an external process. 
ProcessBuilderCreates operating system processes. 
RuntimeAllows Java applications to interface with the environment in which they are running. 
RuntimePermissionRepresents the permission to execute a runtime-related function. 
SecurityManagerWarning: security managers do not provide a secure environment for executing untrusted code. 
ShortThe wrapper for the primitive type short
StackTraceElementA representation of a single stack frame. 
StrictMathClass StrictMath provides basic math constants and operations such as trigonometric functions, hyperbolic functions, exponential, logarithms, etc. 
StringAn immutable sequence of characters/code units (chars). 
StringBufferA modifiable sequence of characters for use in creating strings, where all accesses are synchronized. 
StringBuilderA modifiable sequence of characters for use in creating strings. 
SystemProvides access to system-related information and resources including standard input and output. 
ThreadA Thread is a concurrent unit of execution. 
ThreadGroupThreadGroup is a means of organizing threads into a hierarchical structure. 
ThreadLocal<T>Implements a thread-local storage, that is, a variable for which each thread has its own value. 
ThrowableThe superclass of all classes which can be thrown by the virtual machine. 
VoidPlaceholder class for the Java keyword void

Enums

Thread.StateA representation of a thread's state. 

Exceptions

ArithmeticExceptionThrown when the an invalid arithmetic operation is attempted. 
ArrayIndexOutOfBoundsExceptionThrown when the an array is indexed with a value less than zero, or greater than or equal to the size of the array. 
ArrayStoreExceptionThrown when a program attempts to store an element of an incompatible type in an array. 
ClassCastExceptionThrown when a program attempts to cast a an object to a type with which it is not compatible. 
ClassNotFoundExceptionThrown when a class loader is unable to find a class. 
CloneNotSupportedExceptionThrown when a program attempts to clone an object which does not support the Cloneable interface. 
EnumConstantNotPresentExceptionThrown if an enum constant does not exist for a particular name. 
ExceptionException is the superclass of all classes that represent recoverable exceptions. 
IllegalAccessExceptionThrown when a program attempts to access a field or method which is not accessible from the location where the reference is made. 
IllegalArgumentExceptionThrown when a method is invoked with an argument which it can not reasonably deal with. 
IllegalMonitorStateExceptionThrown when a monitor operation is attempted when the monitor is not in the correct state, for example when a thread attempts to exit a monitor which it does not own. 
IllegalStateExceptionThrown when an action is attempted at a time when the virtual machine is not in the correct state. 
IllegalThreadStateExceptionThrown when an operation is attempted which is not possible given the state that the executing thread is in. 
IndexOutOfBoundsExceptionThrown when a program attempts to access a value in an indexable collection using a value which is outside of the range of valid indices. 
InstantiationExceptionThrown when a program attempts to access a constructor which is not accessible from the location where the reference is made. 
InterruptedExceptionThrown when a waiting thread is activated before the condition it was waiting for has been satisfied. 
NegativeArraySizeExceptionThrown when an attempt is made to create an array with a size of less than zero. 
NoSuchFieldExceptionThrown when the virtual machine notices that a program tries to reference, on a class or object, a field that does not exist. 
NoSuchMethodExceptionThrown when the virtual machine notices that a program tries to reference, on a class or object, a method that does not exist. 
NullPointerExceptionThrown when a program tries to access a field or method of an object or an element of an array when there is no instance or array to use, that is if the object or array points to null
NumberFormatExceptionThrown when an invalid value is passed to a string-to-number conversion method. 
RuntimeExceptionRuntimeException is the superclass of all classes that represent exceptional conditions which occur as a result of executing an application in the virtual machine. 
SecurityExceptionThrown when a security manager check fails. 
StringIndexOutOfBoundsExceptionThrown when the a string is indexed with a value less than zero, or greater than or equal to the size of the array. 
TypeNotPresentExceptionThrown when a program tries to access a class, interface, enum or annotation type through a string that contains the type's name and the type cannot be found. 
UnsupportedOperationExceptionThrown when an unsupported operation is attempted. 

Errors

AbstractMethodErrorThrown by the virtual machine when an abstract method is called. 
AssertionErrorThrown when an assertion has failed. 
ClassCircularityErrorThrown when the virtual machine notices that an attempt is made to load a class which would directly or indirectly inherit from one of its subclasses. 
ClassFormatErrorThrown by a class loader when a class file has an illegal format or if the data that it contains can not be interpreted as a class. 
ErrorError is the superclass of all classes that represent unrecoverable errors. 
ExceptionInInitializerErrorThrown when an exception occurs during class initialization. 
IllegalAccessErrorThrown when the virtual machine notices that a program tries access a field which is not accessible from where it is referenced. 
IncompatibleClassChangeErrorIncompatibleClassChangeError is the superclass of all classes which represent errors that occur when inconsistent class files are loaded into the same running image. 
InstantiationErrorThrown when the virtual machine notices that a program tries to create a new instance of a class which has no visible constructors from the location where new is invoked. 
InternalErrorThrown when the virtual machine notices that it has gotten into an undefined state. 
LinkageErrorLinkageError is the superclass of all error classes that occur when loading and linking class files. 
NoClassDefFoundErrorThrown when the virtual machine is unable to locate a class which it has been asked to load. 
NoSuchFieldErrorThrown when the virtual machine notices that a program tries to reference, on a class or object, a field that does not exist. 
NoSuchMethodErrorThrown when the virtual machine notices that a program tries to reference, on a class or object, a method that does not exist. 
OutOfMemoryErrorThrown when a request for memory is made that can not be satisfied using the available platform resources. 
StackOverflowErrorThrown when the depth of the callstack of the running program excedes some platform or virtual machine specific limit. 
ThreadDeathThreadDeath is thrown when a thread stops executing. 
UnknownErrorThrown when the virtual machine must throw an error which does not match any known exceptional condition. 
UnsatisfiedLinkErrorThrown when an attempt is made to invoke a native for which an implementation could not be found. 
UnsupportedClassVersionErrorThrown when an attempt is made to load a class with a format version that is not supported by the virtual machine. 
VerifyErrorThrown when the virtual machine notices that an attempt is made to load a class which does not pass the class verification phase. 
VirtualMachineErrorVirtualMachineError is the superclass of all error classes that occur during the operation of the virtual machine.