interface I{ void f1(); // 1 public void f2(); // 2 protected void f3(); // 3 private void f4(); // 4 } which lines generate compile time errors?

technology programming languages

  1. compiletime error at lines 1,2,3,4

  2. compiletime error at line 3

  3. compiletime error at line 1

  4. compiletime error at lines 3,4

  5. None of the above

Show answer
Correct Option: D
Explanation:

To solve this question, the user needs to know about the different access modifiers in Java and their effect on the accessibility of methods.

Option A: This option is incorrect. There should be no compile-time errors in the code as all the methods in the interface are correctly defined.

Option B: This option is incorrect. The protected access modifier can be used in interface methods, so there should be no compile-time error at line 3.

Option C: This option is incorrect. The default access modifier can be used in interface methods, so there should be no compile-time error at line 1.

Option D: This option is correct. The private access modifier cannot be used in interface methods as they are implicitly abstract and intended to be implemented by other classes. Thus, there is a compile-time error at line 4. Additionally, the protected access modifier can be used in interface methods, but it may cause issues with implementation, so it is not recommended.

Option E: This option is incorrect. The correct answer is option D.

Therefore, the answer is: D. compiletime error at lines 3,4.

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