Java OCA OCP Practice Question 1557

Question

Given the following enum declaration, how many lines contain compilation errors? 

package mypkg;/*from   w w  w .ja  v a 2s.c  o  m*/


public enum Answer {
   TRUE(-10) { @Override String getName() { return "RIGHT"; }},
   FALSE(-10) { public String getName() { return "WRONG"; }},
   UNKNOWN(0) { @Override public String getName() { return "LOST"; }}

   private final int value;
   Answer(int value) {
      this.value = value;
   }
   public int getValue() {
      return this.value;
   }
   protected abstract String getName();
}
  • A. None. The code compiles as is.
  • B. One
  • C. Two
  • D. Three


C.

Note

The code does not compile since it contains two compilation errors, making Option A incorrect.

The enum list is not terminated with a semicolon (;).

A semicolon (;) is required anytime an enum includes anything beyond just the list of values, such as a constructor or method.

Second, the access modifier of TRUE's implementation of getName() is package-private, but the abstract method signature has a protected modifier.

Since package-private is a more restrictive access than protected, the override is invalid and the code does not compile.

For these two reasons, Option C is the correct answer.

Note that the @Override annotation is optional in the method signature, therefore FALSE's version of getName() compiles without issue.

The Answer constructor does not include a private access modifier, but the constructor compiles without issue.

Enum constructors are assumed to be private if no access modifier is specified, unlike regular classes where package-private is assumed if no access modifier is specified.




PreviousNext

Related