Sunday, July 5, 2015

Java Interview Questions from Java67


Can we overload static method in Java Program
Yes, we can overload static method in Java. In terms of method overloading static method are just like normal methods and in order to overload static method you need to provide another static method with same name but different method signature. Static overloaded method are resolved using Static Binding during compile time. 

In summary, Don't confuse between method overloading and method overriding. In short, you can overload static method in Java but you can not override static method in Java.

Is Java a Pure Object Oriented Programming Language?
There are many things in Java which are not objects e.g. primitive data types e.g. boolean,charshortintlongfloatdouble, different kinds of arithmetic, logical and bitwise operator e.g. +, -*/&&|| etc. 

Can we override private method in Java? -- No
Can we override static method in Java ? -- No

Why main method is public static and void in Java?
main method in Java is public so that its visible to every other class, even which are not part of its package. if its not public JVM classes might not able to access it.

main method is static in Java, so that it can be called without creating any instance. While JVM tries to execute Java program it doesn't know how to create instance of  main class as there is no standard constructor is defined for main class.

main method is void in Java because it doesn't return any thing to caller which is JVM .
Difference between C,C++ and Java main method
Main method in java doesn't return anything and has return type void while main method in C and ++ return int.

J2EE
Difference between GenericServlet vs HttpServlet in Servlet JSP - J2EE question
 GenericServlet is a generic and protocol independent implementation of Servlet interface while HttpServlet implements HTTP protocol specifics.
GenericServlet provides abstract service(ServletRequest, ServletResponse) method to implement which gets called by container whenever it receives request for processing, On the other handHttpServlet overrides service method and provides callback ondoGet(HttpServletRequest request, HttpServletResponse)and doPost(HttpServletRequest request, HttpServletResponse response) whenever it receives HTTP request from GET or POST method. It also provides several other method based upon various HTTP methods of sending request e.g.doPut() or doDelete() to handle HTTP PUT and HTTP DELETE request.

2) Another difference between GenericServlet and HttpServlet is that later is a subclass of GenericServlet and inherit properties of GenericServlet.

3) Generic servlet provides a rather easier way to extend Servlet, its enough to override service method to implementGenericServlet. Apart from extending Servlet interface, it also implements ServletConfig interface and provides way to accept initialization parameter passed to Servlet from web.xml e.g. by using getInitParamter().

Also check: http://java67.blogspot.com/2012/09/top-10-tricky-java-interview-questions-answers.html

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