JAVA 的checked异常和unchecked异常

• 什么是unchecked异常?

即RuntimeException（运行时异常） 不需要try...catch...或throws 机制去处理的异常

• 列举最常用的五种RuntimeException:

这是JAVA认证考试中最常见的题目,事实上,runtime exception中最常见的,经常碰到的,也就5,6种,如下:

ArithmeticException	int a=0; int b= 3/a;
ClassCastException：	Object x = new Integer(0); System.out.println((String)x);
IndexOutOfBoundsException ArrayIndexOutOfBoundsException, StringIndexOutOfBoundsException	int [] numbers = { 1, 2, 3 }; int sum = numbers[3];
IllegalArgumentException NumberFormatException	int a = Interger.parseInt("test");
NullPointerExceptionextends

• 除了RuntimeException，其他继承自java.lang.Exception得异常统称为Checked Exception,他们有多少种呢?

下面是JDK API中列出的异常类: 除了RuntimeException以外的,都是checked Exception

java.lang.Object java.lang.Throwable java.lang.Exception 所有已实现的接口： Serializable 直接已知子类： AclNotFoundException, ActivationException, AlreadyBoundException, ApplicationException, AWTException, BackingStoreException, BadAttributeValueExpException, BadBinaryOpValueExpException, BadLocationException, BadStringOperationException, BrokenBarrierException, CertificateException, ClassNotFoundException, CloneNotSupportedException, DataFormatException, DatatypeConfigurationException, DestroyFailedException, ExecutionException, ExpandVetoException, FontFormatException, GeneralSecurityException, GSSException, IllegalAccessException, IllegalClassFormatException, InstantiationException, InterruptedException, IntrospectionException, InvalidApplicationException, InvalidMidiDataException, InvalidPreferencesFormatException, InvalidTargetObjectTypeException, InvocationTargetException, IOException, JAXBException, JMException, KeySelectorException, LastOwnerException, LineUnavailableException, MarshalException, MidiUnavailableException, MimeTypeParseException, MimeTypeParseException, NamingException, NoninvertibleTransformException, NoSuchFieldException, NoSuchMethodException, NotBoundException, NotOwnerException, ParseException, ParserConfigurationException, PrinterException, PrintException, PrivilegedActionException, PropertyVetoException, RefreshFailedException, RemarshalException, RuntimeException, SAXException, ScriptException, ServerNotActiveException, SOAPException, SQLException, TimeoutException, TooManyListenersException, TransformerException, TransformException, UnmodifiableClassException, UnsupportedAudioFileException, UnsupportedCallbackException, UnsupportedFlavorException, UnsupportedLookAndFeelException, URIReferenceException, URISyntaxException, UserException, XAException, XMLParseException, XMLSignatureException, XMLStreamException, XPathException

我经常碰到的checked exception：

AWTException,

CertificateException,

ClassNotFoundException,

CloneNotSupportedException,

InterruptedException,

InstantiationException,

IllegalClassFormatExceptionm,

IllegalAccessException,

IOException,

InvocationTargetException,

NoSuchFieldException,

NoSuchMethodException,

ParserConfigurationException,

SOAPException,

SQLException,

TimeoutException,