Exception Handling in JAVA

Exceptions let you handle unusual error conditions without cluttering your code with nested ifs after every method call. There are two kinds of Exceptions, checked and unchecked. You don’t need to declare unchecked Exceptions, those that derive from java.lang.Error and java.lang.RuntimeException, in your throws clauses. Checked Exceptions usually derive from java.lang.Exception.
The basic syntax to handle an Exception looks like this:

The

String trickyMethod() throws IOException
{
   int result = readAnotherChar();
   if ( result < 0 ) throw new IOException( "bad data" );
   return result;
}

Collectively, RuntimeException, Error and Exception are derived from Throwable. RuntimeException is derived from Exception, which is derived fromThrowable. Error is derived directly from Throwable.

If you catch RuntimeException you will catch all manner of run time Exceptions (type R).
If you catch Error you will catch all manner of errors (type E).
If you catch Exception you will catch all manner of checked Exceptions and run time Exceptions (type R+C).
If you catch Throwable, you will catch everything, (Type R+E+C );

If the Exception is checked, you must either fob it off on the caller, with the throws clause or catch it yourself. Unchecked Exceptions are ones like running out of RAM that, in general you can’t do much about, or that are not associated with specific problematic code, or that are very common such as IllegalArgumentException orNullPointerException. You don’t have to catch unchecked Exceptions or explicitly fob them off on the caller with throws. The classification of an Exception is not an exact science. It is a little bit like the arbitrary assignment of gender in French or German to objects. You just have to look it up. There is a major clue, Error Exceptions end in the string “Error” while checked Exceptions and RuntimeExceptions end in the string “Exception”.

Exception Name	Type	Package
AbstractMethodError	E	java.lang
AccessControlException	R	java.security
AccessException	C	java.rmi
AclNotFoundException	C	java.security.acl
ActivateFailedException	C	java.rmi.activation
ActivationException	C	java.rmi.activation
AlreadyBoundException	C	javax.naming
ApplicationException	C	org.omg.CORBA.portable
ArithmeticException	R	java.lang
ArrayIndexOutOfBoundsException	R	java.lang
ArrayStoreException	R	java.lang
AttributeInUseException	C	javax.naming.directory
AttributeModificationException	C	javax.naming.directory
AuthenticationException	C	javax.naming
AuthenticationNotSupportedException	C	javax.naming
AWTError	E	java.awt
AWTError	E	java/awt
AWTException	C	java.awt
BadLocationException	C	javax.swing.text
BatchUpdateException	C	java.sql
BindException	C	java.net
CannotProceedException	C	javax.naming
CannotRedoException	R	javax.swing.undo
CannotUndoException	R	javax.swing.undo
CertificateEncodingException	C	java.security.cert
CertificateException	C	java.security.cert
CertificateExpiredException	C	java.security.cert
CertificateNotYetValidException	C	java.security.cert
CertificateParsingException	C	java.security.cert
ChangedCharSetException	C	javax.swing.text
CharConversionException	C	java.io
ClassCastException	R	java.lang
ClassCircularityError	E	java.lang
ClassFormatError	E	java.lang
ClassNotFoundException	C	java.lang
CloneNotSupportedException	C	java.lang
CMMException	R	java.awt.color
CommunicationException	C	javax.naming
ConcurrentModificationException	R	java.util
ConfigurationException	C	javax.naming
ConnectException	C	java.rmi
ConnectIOException	C	java.rmi
ContextNotEmptyException	C	javax.naming
CRLException	C	java.security.cert
DataFormatException	C	java.util.zip
DigestException	C	java.security
EmptyStackException	R	java.util
EOFException	C	java.io
Error	E	java.lang
Exception	C	java.lang
ExceptionInInitializerError	E	java.lang
ExceptionInInitializerError	E	java.lang
ExpandVetoException	C	javax.swing.tree
ExportException	C	java.rmi.server
FileNotFoundException	C	java.io
FontFormatException	C	java.awt
GeneralSecurityException	C	java.security
IllegalAccessError	E	java.lang
IllegalAccessException	C	java.lang
IllegalArgumentException	R	java.lang
IllegalComponentStateException	R	java.awt
IllegalMonitorStateException	R	java.lang
IllegalPathStateException	R	java.awt.geom
IllegalStateException	R	java.lang
IllegalThreadStateException	R	java.lang
ImagingOpException	R	java.awt.image
IncompatibleClassChangeError	E	java.lang
IndexOutOfBoundsException	R	java.lang
IndirectionException	R	org.omg.CORBA.portable
InstantiationError	E	java.lang
InstantiationException	C	java.lang
InsufficientResourcesException	C	javax.naming
InternalError	E	java.lang
InterruptedException	C	java.lang
InterruptedIOException	C	java.io
InterruptedNamingException	C	javax.naming
IntrospectionException	C	java.beans
InvalidAlgorithmParameterException	C	java.security
InvalidAttributeIdentifierException	C	javax.naming.directory
InvalidAttributesException	C	javax.naming.directory
InvalidAttributeValueException	C	javax.naming.directory
InvalidClassException	C	java.io
InvalidDnDOperationException	R	java.awt.dnd
InvalidKeyException	C	java.security
InvalidKeySpecException	C	java.security.spec
InvalidMidiDataException	C	javax.sound.midi
InvalidNameException	C	javax.naming
InvalidObjectException	C	java.io
InvalidParameterException	R	java.security
InvalidParameterSpecException	C	java.security.spec
InvalidSearchControlsException	C	javax.naming.directory
InvalidSearchFilterException	C	javax.naming.directory
InvalidTransactionException	C	javax.transaction
InvocationTargetException	C	java.lang.reflect
IOException	C	java.io
JarException	C	java.util.jar
KeyException	C	java.security
KeyManagementException	C	java.security
KeyStoreException	C	java.security
LastOwnerException	C	java.security.acl
LdapReferralException	C	javax.naming.ldap
LimitExceededException	C	javax.naming
LineUnavailableException	C	javax.sound.sampled
LinkageError	E	java.lang
LinkException	C	javax.naming
LinkLoopException	C	javax.naming
MalformedLinkException	C	javax.naming
MalformedURLException	C	java.net
MarshalException	C	java.rmi
MidiUnavailableException	C	javax.sound.midi
MimeTypeParseException	C	java.awt.datatransfer
MissingResourceException	R	java.util
NameAlreadyBoundException	C	javax.naming
NameNotFoundException	C	javax.naming
NamingException	C	javax.naming
NamingSecurityException	C	javax.naming
NegativeArraySizeException	R	java.lang
NoClassDefFoundError	E	java.lang
NoInitialContextException	C	javax.naming
NoninvertibleTransformException	C	java.awt.geom
NoPermissionException	C	javax.naming
NoRouteToHostException	C	java.net
NoSuchAlgorithmException	C	java.security
NoSuchAttributeException	C	javax.naming.directory
NoSuchElementException	R	java.util
NoSuchFieldError	E	java.lang
NoSuchFieldException	C	java.lang
NoSuchMethodError	E	java.lang
NoSuchMethodException	C	java.lang
NoSuchObjectException	C	java.rmi
NoSuchProviderException	C	java.security
NotActiveException	C	java.io
NotBoundException	C	java.rmi
NotContextException	C	javax.naming
NotOwnerException	C	java.security.acl
NotSerializableException	C	java.io
NullPointerException	R	java.lang
NumberFormatException	R	java.lang
ObjectStreamException	C	java.io
OperationNotSupportedException	C	javax.naming
OptionalDataException	C	java.io
OutOfMemoryError	E	java.lang
ParseException	C	java.text
PartialResultException	C	javax.naming
PolicyError	E	org.omg.CORBA
PrinterAbortException	C	java.awt.print
PrinterException	C	java.awt.print
PrinterIOException	C	java.awt.print
PrivilegedActionException	C	java.security
ProfileDataException	R	java.awt.color
PropertyVetoException	C	java.beans
ProtocolException	C	java.net
ProviderException	R	java.security
RasterFormatException	R	java.awt.image
ReferralException	C	javax.naming
RemarshalException	C	org.omg.CORBA.portable
RemoteException	C	java.rmi
RMISecurityException	C	java.rmi
RuntimeException	R	java.lang
SchemaViolationException	C	javax.naming.directory
SecurityException	R	java.lang
ServerCloneException	C	java.rmi.server
ServerError	E	java.rmi
ServerException	C	java.rmi
ServerNotActiveException	C	java.rmi.server
ServerRuntimeException	C	java.rmi
ServiceUnavailableException	C	javax.naming
SignatureException	C	java.security
SizeLimitExceededException	C	javax.naming
SkeletonMismatchException	C	java.rmi.server
SkeletonNotFoundException	C	java.rmi.server
SocketException	C	java.net
SocketSecurityException	C	java.rmi.server
SQLException	C	java.sql
StackOverflowError	E	java.lang
StreamCorruptedException	C	java.io
StringIndexOutOfBoundsException	R	java.lang
StubNotFoundException	C	java.rmi
SyncFailedException	C	java.io
SystemException	R	org.omg.CORBA
TimeLimitExceededException	C	javax.naming
TooManyListenersException	C	java.util
TransactionRequiredException	C	javax.transaction
TransactionRolledbackException	C	javax.transaction
UndeclaredThrowableException	R	java.lang.reflect
UnexpectedException	R	java.rmi
UnknownError	E	java.lang
UnknownException	R	org.omg.CORBA.portable
UnknownGroupException	C	java.rmi.activation
UnknownHostException	C	java.rmi
UnknownHostException	C	java.net
UnknownObjectException	C	java.rmi.activation
UnknownServiceException	C	java.net
UnknownUserException	C	org.omg.CORBA
UnmarshalException	C	java.rmi
UnrecoverableKeyException	C	java.security
UnsatisfiedLinkError	E	java.lang
UnsupportedAudioFileException	C	javax.sound.sampled
UnsupportedClassVersionError	E	java.lang
UnsupportedDataTypeException	C	java.io
UnsupportedEncodingException	C	java.io
UnsupportedFlavorException	C	java.awt.datatransfer
UnsupportedLookAndFeelException	C	javax.swing
UnsupportedOperationException	R	java.lang
UserException	C	org.omg.CORBA
UTFDataFormatException	C	java.io
VerifyError	E	java.lang
VirtualMachineError	E	java.lang
WriteAbortedException	C	java.io
ZipException	C	java.util.zip