11.5.2

The Class

Error

EXCEPTIONS

The loading process is described in  12.2. The errors

ClassFormatError

,

ClassCircularityError

, and

NoClassDefFoundError

 are described there.

The linking process is described in  12.3. The linking errors are described

there. These errors include

IllegalAccessError

,

 InstantiationError

,

NoSuchFieldError

, and

NoSuchMethodError

, all of which are subclasses of

IncompatibleClassChangeError

, and, also,

UnsatisfiedLinkError

.

The class verification process is described in  12.3.1. The verification failure

error

VerifyError

 is described there.

The class preparation process is described in  12.3.2. The preparation error

described there is

AbstractMethodError

.

The class initialization process is described in  12.4. A virtual machine will

throw the error

ExceptionInInitializerError

 if execution of a static ini 

tializer or of an initializer for a

static

 field results in an exception that is not

an

Error

 or a subclass of

Error

.

11.5.2.2

Virtual Machine Errors

A Java Virtual Machine throws an object that is an instance of a subclass of the

class

VirtualMachineError

 when an internal error or resource limitation pre 

vents it from implementing the semantics of the Java Language. This language

specification and the Java Virtual Machine Specification define the following vir 

tual machine errors:

InternalError

: An internal error has occurred in a Java Virtual Machine,

because of a fault in the software implementing the virtual machine, a fault in

the underlying host system software, or a fault in the hardware. This error is

delivered asynchronously when it is detected, and may occur at any point in a

Java program.

OutOfMemoryError

: A Java Virtual Machine has run out of either virtual or

physical memory, and the automatic storage manager wasn't able to reclaim

enough memory to satisfy an object creation request.

StackOverflowError

: A Java Virtual Machine has run out of stack space for

a thread, typically because the thread is doing an unbounded number of recur 

sive invocations due to a fault in the executing program.

UnknownError

: An exception or error has occurred but, for some reason, a

Java Virtual Machine is unable to report the actual exception or error.

A sophisticated Java program may be designed to handle

OutOfMemoryError

 and

attempt to recover from it, perhaps by carefully dropping references to objects.

212