Java OCA OCP Practice Question 1462

Question

How many lines of the main method fail to compile? 

11:  static interface Printable {} 
12:  static class Rectangle implements Printable {} 
13: //  w ww . j a va2s .  co  m
14:  public static void main(String[] args) { 
15:     Rectangle rect = new Rectangle(); 
16: 
17:     System.out.println(null instanceof Rectangle); 
18:     System.out.println(rect instanceof Printable); 
19:     System.out.println(rect instanceof Rectangle); 
20:     System.out.println(rect instanceof ArrayList); 
21:     System.out.println(rect instanceof Collection); 
22: }
  • A. One
  • B. Two
  • C. Three
  • D. Four


A.

Note

You are allowed to use null with instanceof; it just prints false.

The rect variable is both a Printable and a Rectangle, so lines 18 and 19 print true.

rect is not an ArrayList or Collection.

The compiler only knows that rect is not an ArrayList because ArrayList is a concrete class.

Line 20 does not compile.

The compiler can't definitively state that rect is not a Collection.

Only line 20 fails to compile, and Option A is correct.




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