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 Q61. In a case where there are no instance variables what does the default constructor initialize?Core Java
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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 Q62. What will be the output of following code ?
class BuggyBread2 {       
   private static int counter = 0;     
   void BuggyBread2() {        
      counter = 5;    
   }     
   
   BuggyBread2(int x){
      counter = x;    
   }        

   public static void main(String[] args) {        
      BuggyBread2 bg = new BuggyBread2();        
      System.out.println(counter);    
   } 
}		Core Java
Ans.  Compile time error as it won't find the constructor matching BuggyBread2(). 
Compiler won't provide default no argument constructor as programmer has already defined one constructor. 
Compiler will treat user defined BuggyBread2() as a method, as return type ( void ) has been specified for that. 

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   Like         Discuss         Correct / Improve     java   code   coding   tricky questions   interesting questions   default constructor   constructor
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 Q63. Why every object constructor automatically call super() in Object before its own constructors?Core Java
Ans. Derived object carries the body of its class as well as the body of the parent class. Its body ( member elements ) is initialized using its own class constructor whereas the body ( member elements ) carried from the parent class are initialized using super class constructor. So In order to initialize the elements of the parent class before its own elements are even initialized, super is called.

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   Like         Discuss         Correct / Improve     java   oops   constructor   super   inheritance  object oriented programming (oops)  oops concepts   inheritence     Asked in 1 Companies      intermediate

 Q64. Which of the following is false about Constructors ?

a. Constructor can be overloaded
b. A no argument constructor is provided by the compiler if we declare only constructors with arguments.
c. Constructors shouldn't have any return types , not even void.
d. If super is not explicitly called, still super() is intrinsically added by the compiler.
Core Java
Ans. A no argument constructor is provided by the compiler if we declare only constructors with arguments.

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 Q65. Write code for constructor overloadingCore Java
Ans. http://javasearch.buggybread.com/CodeSnippets/searchCodeSamples.php?&category=code&searchOption&keyword=965

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   Like         Discuss         Correct / Improve     constructor overloading  code  coding     Asked in 2 Companies      basic

 Q66. What is a default constructor ?Core Java
a. Constructor without parameters declared by user
b. Constructor provided by Java if no constructor is declared
c. Constructor with empty body
d. All of the above

Ans.b. Constructor provided by Java if no constructor is declared
 Q67. How can we create objects if we make the constructor private ?Core Java
a. We can't create objects if constructor is private
b. We can only create objects if we follow singleton pattern
c. We can only create one object
d. We can create new object through static method or static block

Ans.d. We can create new object through static method or static block
 Q68. With the following code, Which is a valid way to initialize ?
public class BuggyBread {

   private String element1;

   private String element2;

   private BuggyBread(String element1, String element2){
      this.element1 = element1;
      this.element2 = element2;
   }

   public static class Builder {
   
      private String element1;

      private String element2;

      Builder(BuggyBread buggybread){
         element1 = buggybread.element1;
         element2 = buggybread.element2;
      }

      Builder withElement1(String element1){
         this.element1 = element1;
         return this;
      }

      Builder withElement2(String element2){
         this.element2 = element2;
         return this;
      }

      BuggyBread build(){
         BuggyBread buggybread = new BuggyBread(element1,element2);
         return buggybread;
      }
   }
}		Core Java
a. BuggyBread buggybread = new BuggyBread();
b. BuggyBread buggybread = new BuggyBread("element1","element2");
c. BuggyBread.Builder builder = new BuggyBread.Builder();
d. BuggyBread.Builder builder = new BuggyBread.Builder("element1","element2");

Ans.d. BuggyBread.Builder builder = new BuggyBread.Builder("element1","element2");
 Q69. What will be the output of following code ?

public class BuggyBread {
   
   private int x;
   private int y;
   
   BuggyBread(int x,int y){};
   
   public static void main(String[] args){
      BuggyBread buggybread = new BuggyBread();
      System.out.println(buggybread.x);
   }
}		Core Java
a. 0
b. null
c. compilation error due to uninitialized element
d. compilation error due to constructor

Ans.d. compilation error due to constructor
 Q70. What will be the output of following code ?

public class BuggyBread {

   private int x;
   private Integer y;

   private BuggyBread(int x,int y){};

   public static void main(String[] args){
      BuggyBread buggybread = new BuggyBread(1,2);
      System.out.println(buggybread.x);
   }
}		Core Java
a. compilation error due to private constructor
b. compilation error due to uninitialized elements
c. 0 null
d. 0 0

Ans.c. 0 null
 Q71. What is the problem with this code ?

public class Car extends Vehicle{   
   int x;
   
   Car(int y){
      x = 5;
   }
   
   Car(){
      this(5);
      super();
   }
}		Core Java
a. We cannot overload constructors
b. Constructors should have type
c. we should have called super() before this(5)
d. We cannot have both super() and this() in a constructor

Ans.d. We cannot have both super() and this() in a constructor
 Q72. What is the problem with this code ?

public class Car extends Vehicle{
   int x;

   Car(int y){
      x = 5;
   }

   Car(){
      super();
      this.x = 5;
   }
}		Core Java
a. We cannot overload constructors
b. We cannot call super in overloaded constructor
c. we cannot have this and super in constructor
d. There is no problem

Ans.d. There is no problem
 Q73. The following code is an example of

public class Car extends Vehicle{
   int x;

   Car(int y){
      x = 5;
   }

   Car(){
      this(5);
   }
}		Core Java
a. Constructor Overloading
b. Constructor Chaining
c. Both Constructor Overloading and Chaining
d. None of above

Ans.c. Both Constructor Overloading and Chaining
 Q74. What is the problem with following code ?

public class Car extends Vehicle{
   int x;

   void Car(int y){
      x = 5;
   }

   void Car(){
      this(5);
   }
}		Core Java
a. We cannot use this() within normal method
b. We cannot chain methods
c. We cannot overload constructors
d. We cannot use return type void with overloaded methods

Ans.a. We cannot use this() within normal method
 Q75. Default Constructor is provided by Java , if ..Core Java
a. No constructor is provided by coder
b. No argument constructor is not provided by Coder
c. No Constructor is provided by coder initializing fields to null and primitive default values
d. No argument constructor is provided by coder

Ans.a. No constructor is provided by coder
 Q76. Default Constructor is provided by Java ... Core Java
a. To Reserve Memory
b. To provide at least one instance method
c. To Make it look good
d. To initialize the object state

Ans.d. To initialize the object state
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