Which of the following modifier combination is legal for top level class declaration

Which two of the following are legal declarations for nonnested classes and interfaces?

1. final abstract class Test {}
2. public static interface Test {}
3. final public class Test {}
4. protected abstract class Test {}
5. protected interface Test {}
6. abstract public class Test {}

Answer: Option C

Explanation:

(3), (6). Both are legal class declarations.

(1) is wrong because a class cannot be abstract and final—there would be no way to use such a class. (2) is wrong because interfaces and classes cannot be marked as static. (4) and (5) are wrong because classes and interfaces cannot be marked as protected.

But class can't marked as both fianl and abstract

Then we will not be able to Provide body to the method declared in Interface. This will lead to uselessness of interface.

So Java Compiler will say WTF! This Is An "illegal combination of modifiers".

This code will compile. Answer number (2) should be valid, although I have no idea how to use such construction.

What is the most restrictive access modifier that will allow members of one class to have access to members of another class in the same package?

Answer: Option E

Explanation:

default access is the "package oriented" access modifier.

Option A and C are wrong because public and protected are less restrictive. Option B and D are wrong because abstract and synchronized are not access modifiers.

Which of the following is/are legal method declarations?

1. protected abstract void m1();
2. static final void m1(){}
3. synchronized public final void m1() {}
4. private native void m1();

Answer: Option D

Explanation:

All the given statements are legal declarations.

Which cause a compiler error?

Answer: Option B

Explanation:

Option B generates a compiler error: <identifier> expected. The compiler thinks you are trying to create two arrays because there are two array initialisers to the right of the equals, whereas your intention was to create one 3 x 3 two-dimensional array.

To correct the problem and make option B compile you need to add an extra pair of curly brackets:

int [ ] [ ] scores = { {2,7,6}, {9,3,45} };