虛擬機器產生異常的原由與處理
產生原因：1。由於不正常的語句背虛擬機器檢測到。丟擲異常在語句執行點。可能情況有：違反語義的操作如陣列過界；資源越界；連線程式時出錯
 2。java程式碼執行throws語句
 3。非同步異常：ThreadGroup的stop()方法呼叫與虛擬機器內部發生錯誤。
處理異常：封閉try內部程式碼轉到靠try最近的catch語句中，在沒有catch語句情況下該執行緒停止，只有finnaly語句執行；並且當其執行緒父類
 ThreadGroup呼叫unCatchedException後才終止該執行緒。
異常分類：（java.lang下）
        Exception:
 AclNotFoundException, ActivationException, AlreadyBoundException, ApplicationException,
 AWTException, BackingStoreException, BadLocationException, CertificateException, ClassNotFoundException,
 CloneNotSupportedException, DataFormatException, DestroyFailedException, ExpandVetoException,
 FontFormatException, GeneralSecurityException, GSSException, IllegalAccessException,
 InstantiationException, InterruptedException, IntrospectionException, InvalidMidiDataException,
 InvalidPreferencesFormatException, InvocationTargetException, IOException, LastOwnerException,
 LineUnavailableException, MidiUnavailableException, MimeTypeParseException, NamingException,
 NoninvertibleTransformException, NoSuchFieldException, NoSuchMethodException, NotBoundException,
 NotOwnerException, ParseException, ParserConfigurationException, PrinterException, PrintException,
 PrivilegedActionException, PropertyVetoException, RefreshFailedException, RemarshalException,
 RuntimeException, SAXException, ServerNotActiveException, SQLException, TooManyListenersException,
 TransformerException, UnsupportedAudioFileException, UnsupportedCallbackException,
 UnsupportedFlavorException, UnsupportedLookAndFeelException, URISyntaxException,
 UserException, XAException
 其中不受檢測的執行期異常類：RuntimeException類
 ArithmeticException, ArrayStoreException, BufferOverflowException, BufferUnderflowException,
 CannotRedoException, CannotUndoException, ClassCastException, CMMException,
 ConcurrentModificationException, DOMException, EmptyStackException, IllegalArgumentException,
 IllegalMonitorStateException, IllegalPathStateException, IllegalStateException, ImagingOpException,
 IndexOutOfBoundsException, MissingResourceException, NegativeArraySizeException, NoSuchElementException,
 NullPointerException, ProfileDataException, ProviderException, RasterFormatException, SecurityException,
 SystemException, UndeclaredThrowableException, UnmodifiableSetException, UnsupportedOperationException

 Error:
 AssertionError, AWTError, CoderMalfunctionError, FactoryConfigurationError, LinkageError, ThreadDeath,
 TransformerFactoryConfigurationError, VirtualMachineError

(未完)