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Interview Questions and Answers for 'Object creation' - 6 question(s) found - Order By Newest

Frequently asked in Infosys and HCL Technologies ( Based on 2 feedback )
 Q1. What are different ways of object creation in Java ?Core Java
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Ans. Using new operator - new xyzClass()

Using factory methods - xyzFactory.getInstance( )

Using newInstance( ) method - (Class.forName(xyzClass))emp.newInstance( )

By cloning an already available object - (xyzClass)obj1.clone( )

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   Like      Discuss      Correct / Improve     java   oops   object creation   new operator   class.forname   cloning   ebay     Intelligrape  Infosys  Polaris  British Telecom (BT)  Vyom Labs  Deutsche Bank  HCL Technologies      expert


 Q2. Describe what happens when an object is created in Java ?Core Java
Anonymous
Ans. 1. Memory is allocated from heap to hold all instance variables and implementation-specific data of the object and its superclasses. Implemenation-specific data includes pointers to class and method data.
2. The instance variables of the objects are initialized to their default values.
3. The constructor for the most derived class is invoked. The first thing a constructor does is call the constructor for its superclasses. This process continues until the constructor for java.lang.Object is called,as java.lang.Object is the base class for all objects in java.
4. Before the body of the constructor is executed, all instance variable initializers and initialization blocks are executed. Then the body of the constructor is executed. Thus, the constructor for the base class completes first and constructor for the most derived class completes last.

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   Like      Discuss      Correct / Improve     java   memory management   object creation   advanced   ebay


 Q3. Does Constructor creates the object ?Core Java
Anonymous
Ans. New operator in Java creates objects. Constructor is the later step in object creation. Constructor's job is to initialize the members after the object has reserved memory for itself.

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   Like      Discuss      Correct / Improve     java   constructor   object creation      intermediate        rare


 Q4. Difference between new operator and Class.forName().newInstance() ?
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Ans. new operator is used to statically create an instance of object. newInstance() is used to create an object dynamically ( like if the class name needs to be picked from configuration file ). If you know what class needs to be initialized , new is the optimized way of instantiating Class.

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   Like      Discuss      Correct / Improve     java   oops   object instantiation   object creation   class.forname   newinstance   new operator   difference between   advanced      intermediate


 Q5. Difference between Class#getInstance() and new operator ?
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Ans. Class.getInstance doesn't call the constructor whereas if we create an object using new operator , we need to have a matching constructor or copiler should provide a default constructor.

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   Like      Discuss      Correct / Improve     java   constructor   object creation   default constructor   getinstance   new operator


 Q6. In a case where there are no instance variables what does the default constructor initialize?Core Java
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Ans. Java expects the superclass ( Object Class ) constructor to be called while creation of any object. So super constructor is called in case there are no instance variables to initialize.

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   Like      Discuss      Correct / Improve     java   constructor   object creation   default constructor   super

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