Java OCA OCP Practice Question 1479

Question

Given the following code,

which of these constructors can be added to class MyClass without causing a compile time error? 

class MyBaseClass { 
   int i; 
   public MyBaseClass (int x)  { this.i = x;  } 
} 
class MyClass extends MyBaseClass { 
   int j; 
   public MyClass (int x, int y)  { super (x);  this.j = y;  } 
}

Select 2 options

  • A. MyClass ( ) { }
  • B. MyClass (int y ) { j = y; }
  • C. MyClass (int y ) { super (y*2 ); j = y; }
  • D. MyClass (int y ) { i = y; j = y*2; }
  • E. MyClass (int z ) { this (z, z); } 


Correct Options are  : C E

Note

To construct an instance of a sub class, its super class needs need to be constructed first.

Since an instance can only be created via a constructor, some constructor of the super class has to be invoked.

Either you explicitly call it or the compiler will add super() as the first line of the sub class constructor.




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