Java Packages Interview Question & Answers

All Packages

Q) Thread Class

Methods: -

getName()	run()
getPriority()	Sleep()
isAlive()	Start()
join()

Q) Object class

All other classes are sub classes of object class, Object class is a super class of all other class.

Methods: -

	void notify()			void notifyAll()
	Object clone()			Sting toString()
	boolean equals(Object			void wait()
	object)
	void finalize()			void wait(long milliseconds, int
				nanoseconds)
	int hashcode()
Q) throwable class
Methods: -
	String getMessage()		Void printStackTrace()
	String toString()		Throwable fillInStackTrace()
Q) Javax.servlet Package
	Interfaces				Classes	Exceptions
	Servlet				GenericServlet	ServletExceptio
						n
	ServletConfig				ServletInputStream	UnavaliableExc
						eption
	ServletContext				ServletOutputStream
	ServletRequest				ServletContextAttribut
					eEvent
	ServletResponse
	SingleThreadModel
	ServletContextListener
	ServletContextAttributeList
	Ener
	ServletContextInitialization
	parameters
	ServletRequestAttributeList
	Ener
	ServletRequestListner
	Filter
	FilterChain
	FilterConfig
	RequestDispatcher

 GenericServlet (C)à public void destroy();

public String getInitParameter(String name); 

public Enumeration getInitParameterNames(); 

public ServletConfig getServletConfig(); 

public ServletContext getServletContext(); 

public String getServletInfo();

public void init(ServletConfig config) throws ServletException;

public void log(String msg);

public abstract void service(ServletRequest req, ServletResponse res)

ServletInputStream (C)à public int readLine(byte b[], int off, int len)

ServletOutputStream (C)à public void print(String s) throws IOException; 

                                            public void println() throws IOException;

ServletContextAttributeEvent (C) à public void attributeAdded( ServletContextAttributeEvent scab)

 public void attributeRemoved( ServletContextAttributeEvent scab)

 public void attributeReplaced( ServletContextAttributeEvent scab)

Servlet (I) à public abstract void destroy();

public abstract ServletConfig getServletConfig(); 

public abstract String getServletInfo();

public abstract void init(ServletConfig config) throws ServletException; 

public abstract void service(ServletRequest req, ServletResponse res)

ServletConfig (I) à public abstract String getInitParameter(String name); 

                                public abstract Enumeration getInitParameterNames();

                                public abstract ServletContext getServletContext();

ServletContext (I) à public abstract Object getAttribute(String name);

                             public abstract String getRealPath(String path); 

                             public abstract String getServerInfo();

   public abstract Servlet getServlet(String name) throws ServletException;

   public abstract Enumeration getServletNames();

   public abstract Enumeration getServlets();

   public abstract void log(Exception exception, String msg);

ServletRequest (I) à public abstract Object getAttribute(String name); 

                                  public abstract String getParameter(String name); 

                                  public abstract Enumeration getParameterNames();

public abstract String[] getParameterValues(String name); 

public abstract String getRealPath(String path);

public abstract String getRemoteAddr(); 

public abstract String getRemoteHost(); 

public abstract String getServerName(); 

public abstract int getServerPort();          

RequestDispatcher getRequestDispatcher(String path);

public int getLocalPort();           // servlet 2.4

public int getRemotePort();   // servlet 2.4

public String getLocalName(); // servlet 2.4 public String getLocalAddr(); // servlet 2.4

ServletResponse (I) à  public abstract String getCharacterEncoding();

public abstract PrintWriter getWriter() throws IOException; 

public abstract void setContentLength(int len);

public abstract void setContentType(String type);

Q) Javax.servlet.Http Package

Interfaces	Classes	Exceptions
HttpServletRequest	Cookies	ServletException
HttpServletResponse	HttpServlet (Abstarct	UnavaliableExcep
	Class)	tion
HttpSession	HttpUtils
HttpSessionListener	HttpSessionBindingEven
	t
HttpSessionActivationLis
tener
HttpSessionAttributeList
ener
HttpSessionBindingListe
ner
HttpSessionContext
(deprecated)
Filter

ServletContextListener (I) à public void contextInitialized(ServletContextEvent event)

public void contextDestroyed(ServletContextEvent

event)

ServletContextAttributeListener (I)à 

public void attributeAdded(ServletContextAttributeEvent scab)

public void attributeRemoved(ServletContextAttributeEvent scab)

public void attributeReplaced(ServletContextAttributeEvent scab)

ServletContextInitilazation parameters à

Cookies (C) à public Object clone();

public int getMaxAge(); 

public String getName(); 

public String getPath(); 

public String getValue(); 

public int getVersion(); 

public void setMaxAge(int expiry); public void setPath(String uri);

                        public void setValue(String newValue); 

                        public void setVersion(int v); 

HttpServlet (C) àHttpServletResponse res)

protected void doGet (HttpServletRequest req, HttpServletResponse res)

protected void doOptions(HttpServletRequest req, HttpServletResponse res)

protected void doPost(HttpServletRequest req, HttpServletResponse res)

protected void doPut(HttpServletRequest req, HttpServletResponse res)

protected void doTrace(HttpServletRequest req, HttpServletResponse res)

protected long getLastModified(HttpServletRequest req); protected void service(HttpServletRequest req,

HttpServletResponse res)

                       

                   HttpSessionbindingEvent (C) à public String getName(); 

                                                                  public HttpSession getSession();

                   HttpServletRequest (I) à public abstract Cookie[] getCookies(); 

                                 public abstract String getHeader(String name); 

                                 public abstract Enumeration getHeaderNames();

                                 public abstract String getQueryString();

public abstract String getRemoteUser();

public abstract String getRequestedSessionId(); 

public abstract String getRequestURI();

public abstract String getServletPath();

public abstract HttpSession getSession(boolean create); 

public abstract boolean isRequestedSessionIdFromCookie(); 

public abstract boolean isRequestedSessionIdFromUrl(); 

public abstract boolean isRequestedSessionIdValid();

                HttpServletResponse (I) à public abstract void addCookie(Cookie cookie); 

                         public abstract String encodeRedirectUrl(String url);

                         public abstract String encodeUrl(String url);

        public abstract void sendError(int sc, String msg) throws IOException;

      public abstract void sendRedirect(String location) throws IOException;

public abstract void addIntHeader(String header, int value);

public abstract void addDateHeader(String header, long value);

public abstract void setHeader(String name, String value); 

public abstract void setIntHeader(String header, int

value);

public abstract void setDateHeader(String header, long value);

public void setStatus(); 

HttpSession (I) à public abstract long getCreationTime();

public abstract String getId();

public setAttribute(String name, Object value); 

public getAttribute(String name, Object value); 

public remove Attribute(String name, Object value); 

public abstract long getLastAccessedTime();

public abstract HttpSessionContext getSessionContext();

public abstract Object getValue(String name);

public abstract String[] getValueNames();

public abstract void invalidate();

public abstract boolean isNew();

public abstract void putValue(String name, Object value); 

public abstract void removeValue(String name);

public setMaxInactiveIntervel();

HttpSessionListener (I) à public void sessionCreated(HttpSessionEvent event)

public void sessionDestroyed(HttpSessionEvent

event)

HttpSessionAttributeListener (I) à public void attributeAdded(ServletContextAttributeEvent scab)

public void attributeRemoved(ServletContextAttributeEvent scab)

public void attributeReplaced(ServletContextAttributeEvent scab)

HttpSessionBindingListener (I) à public void

HttpSessionBindingListener.valueBound(HttpSessionBindingEvent event) 

public void

HttpSessionBindingListener.valueUnbound(HttpSessionBindingEvent event)

HttpSessionActivationListener (I) à

public void sessionDidActivate(HttpSessionEvent event) 

public void sessionWillpassivate(HttpSessionEvent event)

Filter (i) à

public void doFilter (ServletRequest request, ServletResponse response, FilterChain chain)

public FilterConfig getFilterConfig()

public void setFilterConfig (FilterConfig filterConfig)

Q) java.sql Package

Interfaces	Classes	Exceptions
Connection	DriverManager
CallableStatement	Date	ClassNotFoundException
Driver	TimeStamp	Instantiation Exception

PreparedStatement	Time
ResultSet	Types
ResultSetMetaData	SQL Exception, SQL
	Warnings
Statement
DatabaseMetaData
Array
ParameterMetaData
Clob, Blob
SQLInput, SQLOutput,
SQLPermission
Savepoint

Q) javax.sql Package

	Interfaces				Classes		Exceptions
	ConnectionEventListener				ConnectionEvent
	ConnectionPoolDataSource				RowsetEvent
	DataSource
	PooledConnection
	RowSet
	RowSetListener
	RowSetMetaDate
	RowSetReader/Writer
	XAConnection
	XADataSource
Q) j	ava.lang Package
	Interfaces		Classes			Exceptions
	Cloneable		Double, Float, Long,			ArithmeticException,
			Integer, Short, Byte,			ArrayIndexOutOfBoundOf.E,
			Boolean, Character,			ClassCast.E, ClassNotFound.E
	Runnable		Class, ClassLoader			IlleAcess.E, IllegalArgument.E
	Comparable		Process, RunTime, Void			IllegalSate.E, NullPointer.E
			String, StringBuffer			NoSuchField.E,
						NoSuchMethod.E
			Thread, ThreadGroup			NumberFormat.E
Q) java.IO Package
	Interfaces			Classes			Exceptions
	DataInputstream			BufferInputstream,
				BufferOutputStream
	DataOutputstream			BufferReader, BufferWriter
	ObjectInputStream			ByteArrayInputStream,
				ByteArrayOutputstream
	ObjectOutputstrea			CharacterarrayReader,
	m			CharacterArayWriter
	Serializable			DataInputStream,
				DataOutputStream
	Externializable			Filereader, FileWriter
				ObjectInputStream,
				ObjectOutputStream