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Core Java interview questions – Part 6

March 18th, 2012 Albin Joseph Posted in Core Java interview questions 11 Comments »

91. What is java byte code?
Byte code is an sort of intermediate code. The byte code is processed by virtual machine.

92. What is method overloading?
Method overloading is the process of creating a new method with the same name and different signature.

93. What is method overriding?
Method overriding is the process of giving a new definition for an existing method in its child class.
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Core Java interview questions – Part 7

March 15th, 2012 Albin Joseph Posted in Core Java interview questions 1 Comment »

106. What is java collections?
Java collections is a set of classes, that allows operations on a collection of classes.

107. Can we compile a java program without main?
Yes, we can. In order to compile a java program, we don’t require any main method. But to execute a java program we must have a main in it (unless it is an applet or servlet). Because main is the starting point of a java program.
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Core Java interview questions – Part 8

March 7th, 2012 Albin Joseph Posted in Core Java interview questions No Comments »

121. What is an interface?
An interface is a collection of method declarations and constants. In java interfaces are used to achieve multiple inheritance. It sets a behavioral protocol to all implementing classes.

122. What is an abstract class?
An abstract class is an incomplete class. An abstract class is defined with the keyword abstract . We cannot create an object of the abstract class because it is not complete. It sets a behavioral protocol for all its child classes.
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Core Java interview questions – Part 9

March 6th, 2012 Albin Joseph Posted in Core Java interview questions No Comments »

136. Why Java is not 100% pure object oriented language?
Because java uses primitives.

137. Why ArrayList is faster than Vector?
Because Vector is synchronized. Synchronization reduces the performance.

138. What is the security mechanism used in java?
Java uses sand box security model.
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Core Java interview questions – Part 10

February 20th, 2012 Albin Joseph Posted in Core Java interview questions No Comments »

151. What is meant by Open Source ?
In general, open source refers to any program whose source code is made available for use or modification as users or other developers see fit. Open source software is usually developed as a public collaboration and made freely available.

152. How do you send data from an applet to Servlet ? What are the steps involved in it ?
You can use the java.net.URLConnection and java.net.URL classes to open a standard HTTP connection to the web server. The server then passes this information to the servlet in the normal way.

Basically, the applet pretends to be a web browser, and the servlet doesn’t know the difference. As far as the servlet is concerned, the applet is just another HTTP client.
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Core Java interview questions – Part 11

February 12th, 2012 Albin Joseph Posted in Core Java interview questions No Comments »

166. What is aggregation?
It is a special type of composition. If you expose all the methods of a composite class and route the method call to the composite method through its reference, then it is called aggregation

167. What are the different methods available in Object?
clone, equals, wait, finalize, getClass, hashCode, notify, notifyAll, toString
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Core Java interview questions – Part 12

February 7th, 2012 Albin Joseph Posted in Core Java interview questions No Comments »

181. What is an Object and how do you allocate memory to it?
Object is an instance of a class and it is a software unit that combines a structured set of data with a set of operations for inspecting and manipulating that data. When an object is created using new operator, memory is allocated to it.

182. What is UNICODE?
Unicode is used for internal representation of characters and strings and it uses 16 bits to represent each other.
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