Java OCA OCP Practice Question 2801

Question

Given this code in a method: 

4.     Integer[][] la = {{1,2}, {3,4,5}};  
5.     Number[] na = la[1];  
6.     Number[] na2 = (Number[])la[0];  
7.     Object o = na2;  
8.     la[1] = (Number[])o;  
9.     la[0] = (Integer[])o;

What is the result? (Choose all that apply.)

  • A. Compilation succeeds.
  • B. Compilation fails due to an error on line 4.
  • C. Compilation fails due to an error on line 5.
  • D. Compilation fails due to an error on line 6.
  • E. Compilation fails due to an error on line 7.
  • F. Compilation fails due to an error on line 8.
  • G. Compilation fails due to an error on line 9.
  • H. Compilation succeeds but an exception is thrown at runtime.


F   is correct.

Note

Integer extends Number, so you can't refer an Integer[] reference to a Number[] (an Integer can do things a Number can't.).




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