Multiple choice technology programming languages

Given: 

1. enum A { A } 
2. class E2 { 
3.   enum B { B } 
4.   void C() { 
5.     enum D { D } 
6.   } 
7. }

Which statements are true? (Choose all that apply.)

  1. If only line 1 is removed the code compiles.

  2. If only line 3 is removed the code compiles.

  3. If only line 5 is removed the code compiles.

  4. If lines 1 and 3 are removed the code compiles

  5. If lines 1, 3 and 5 are removed the code compiles.
Reveal answer Fill a bubble to check yourself
C,E Correct answer
Explanation

Java doesn't allow enum declarations inside methods (line 5). Removing line 5 eliminates this syntax error, allowing compilation. Option C is correct. Removing all three enum declarations (lines 1, 3, 5) leaves only the class and method structure without any nested enums, which is valid Java - option E is correct. Options A, B, and D are incorrect because they still include the method-local enum declaration on line 5.

AI explanation

To answer this question, we need to understand the rules and restrictions regarding the declaration and usage of enums in Java.

In Java, an enum is a special data type that allows for a variable to be a set of predefined constants. Each constant is defined within the enum. Enums can only be declared at the top level of a class or interface, or within a class (as a member) but not inside a method.

Let's go through each option to understand why it is correct or incorrect:

Option A) If only line 1 is removed the code compiles. This option is incorrect because removing line 1 would remove the declaration of enum A. Since enum A is not used in the code, its removal does not affect the compilation.

Option B) If only line 3 is removed the code compiles. This option is incorrect because removing line 3 would remove the declaration of enum B. However, enum B is used within the class E2, so its removal would result in a compilation error.

Option C) If only line 5 is removed the code compiles. This option is correct because removing line 5 would remove the declaration of enum D, which is a local enum declared inside the method C(). Since enum D is not used outside of the method, its removal does not affect the compilation.

Option D) If lines 1 and 3 are removed the code compiles. This option is incorrect because removing line 1 would remove the declaration of enum A, and removing line 3 would remove the declaration of enum B. Since enum B is used within the class E2, its removal would result in a compilation error.

Option E) If lines 1, 3, and 5 are removed the code compiles. This option is correct because removing line 1 would remove the declaration of enum A, removing line 3 would remove the declaration of enum B, and removing line 5 would remove the declaration of enum D. Since enum B is used within the class E2, its removal would result in a compilation error. However, since enum D is a local enum declared inside the method C(), its removal does not affect the compilation.

Therefore, the correct answer is: C. If only line 5 is removed the code compiles. E. If lines 1, 3, and 5 are removed the code compiles.

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