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| Core java - Interview Questions and Answers for 'Avis' - 10 question(s) found - Order By Newest | ||||
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| Ans. OOPs or Object Oriented Programming is a Programming model which is organized around Objects instead of processes. Instead of a process calling series of processes, this model stresses on communication between objects. Objects that all self sustained, provide security by encapsulating it's members and providing abstracted interfaces over the functions it performs. OOP's facilitate the following features 1. Inheritance for Code Reuse 2. Abstraction for modularity, maintenance and agility 3. Encapsulation for security and protection 4. Polymorphism for flexibility and interfacing | ||||
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| Ans. 1. Overriding method can not be more restrictive than the overridden method. reason : in case of polymorphism , at object creation jvm look for actual runtime object. jvm does not look for reference type and while calling methods it look for overridden method. If by means subclass were allowed to change the access modifier on the overriding method, then suddenly at runtime when the JVM invokes the true objects version of the method rather than the reference types version then it will be problematic 2. In case of subclass and superclass define in different package, we can override only those method which have public or protected access. 3. We can not override any private method because private methods can not be inherited and if method can not be inherited then method can not be overridden. | ||||
 Sample Code for Overriding | ||||
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| Discuss Correct / Improve java overriding access specifier inheritence oops polymorphism object oriented programming (oops) oops concepts runtime polymorphism object oriented programming (oops) oops concepts Asked in 4 Companies | ||||
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| Ans. Polymorphism means the condition of occurring in several different forms. Polymorphism in Java is achieved in two manners 1. Static polymorphism is the polymorphic resolution identified at compile time and is achieved through function overloading whereas 2. Dynamic polymorphism is the polymorphic resolution identified at runtime and is achieved through method overriding. | ||||
| Sample Code for overloading Sample Code for overriding | ||||
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| Discuss Correct / Improve polymorphism object oriented programming (oops) oops concepts oops concepts Asked in 108 Companies Basic frequent | ||||
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| Ans. A static initialization block is a normal block of code enclosed in braces, { }, and preceded by the static keyword. Here is an example: static { // whatever code is needed for initialization goes here } A class can have any number of static initialization blocks, and they can appear anywhere in the class body. The runtime system guarantees that static initialization blocks are called in the order that they appear in the source code. | ||||
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| Ans. The accessibility (public, protected, etc.) of the inner class is defined by the outer class. Just like top-level classes, an inner class can extend a class or can implement interfaces. Similarly, an inner class can be extended by other classes, and an inner interface can be implemented or extended by other classes or interfaces. An inner class can be declared final or abstract.Inner classes can have inner classes, but you will have a hard time reading or understanding such complex nesting of classes. | ||||
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| Ans. int count = 15; int[] fibonacci = new int[count]; fibonacci[0] = 0; fibonacci[1] = 1; for(int x=2; x < count; x++){ fibonacci[x] = fibonacci[x-1] + fibonacci[x-2]; } for(int x=0; x< count; x++){ System.out.print(fibonacci[x] + " "); } | ||||
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| Ans. Class is a template using which objects are created in memory. It's kind of a mold using which objects with body / state are made. | ||||
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| This question was recently asked at 'Nagravision'.This question is still unanswered. Can you please provide an answer. | ||||
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| Ans. Assigning a value of one type to a variable of another type is known as Type Casting. Example : int x = 10; byte y = (byte)x; In Java, type casting is classified into two types, Widening Casting(Implicit) widening-type-conversion and Narrowing Casting (Explicitly done) narrowing-type-conversion. Widening or Automatic type converion - Automatic Type casting take place when,the two types are compatible and the target type is larger than the source type Example : public class Test { public static void main(String[] args) { int i = 100; long l = i; //no explicit type casting required float f = l;//no explicit type casting required System.out.println("Int value " i); System.out.println("Long value " l); System.out.println("Float value " f); } } Narrowing or Explicit type conversion - When you are assigning a larger type value to a variable of smaller type, then you need to perform explicit type casting. Example : public class Test{ public static void main(String[] args) { double d = 100.04; long l = (long)d; //explicit type casting required int i = (int)l;//explicit type casting required System.out.println("Double value " d); System.out.println("Long value " l); System.out.println("Int value " i); } } | ||||
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Overridden methods must have the same ... 
