JAVA 的checked错误和unchecked错误

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