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| No. | Answer | Remark | |
|---|---|---|---|
| 1 | e | volatile | An abstract method declaration provides no method body. If one abstract method is appears within a class declaration, then the entire class must be declared abstract and the class can not be instantiated. The access modifiers, private, protected and public, can be applied to a method. The field modifiers, transient and volatile, are not applicable to method declarations. |
| 2 | d | transient | A final method can not be overridden. A static method is associated with a class, but not a particular instance of the class. A thread can not enter a synchronized method without first acquiring a lock. The field modifiers, transient and volatile, are not applicable to method declarations. A native method is implemented in platform-dependent code. |
| 3 | a b e f g | final private static synchronized native | A final or private method can not be overridden, and can not be abstract. An abstract method declaration provides no implementation of the method, and all implementation details are left to the overriding method in the subclass. The synchronized modifier specifies an implementation detail that can be omitted from the declaration of an overriding method of a subclass, so it makes no sense to allow the use of the synchronized modifier in an abstract method declaration. |
| 4 | e | None of the above. | An abstract method of a subclass can override by an abstract method of a superclass. The overriding abstract method declaration can be a good place to add comments. An abstract method of a subclass can override a concrete implementation of a method of a superclass. An abstract method declaration can have a throws clause. The body of an abstract method is a semicolon. |
| 5 | d | The keyword, super, may be used in the body of a static method. | The keyword, this, refers to the instance on which the method has been invoked. A static method--also known as a class method-- is not invoked on a particular instance of an object, but is instead invoked on the class. Since a static method is not associated with a particular instance, an attempt to use the keyword, this, within the body of a static method results in a Compile-time error. Similarly, the keyword, super, can not be used within the body of a static method. |
| 6 | a b e | A final method can not be overridden. All methods declared in a final class are implicitly final. A machine-code generator can inline the body of a final method. | All methods declared in a final class are implicitly final. It is permissible--but not required--that all such methods be explicitly declared final. All private methods are implicitly final. It is permissible--but not required--that all private methods be explicitly declared final. The body of an inline method is inserted directly into the code at the point where the method is invoked. If the method is invoked at 10 different points in the code, then the body can be copied to all 10 points. Inline code runs very quickly, because it removes the need to do the work associated with a method invocation. If the method is executed repeatedly in a loop, then inlining can improve performance significantly. The machine-code generator has the option to inline a final method. |
| 7 | a c e | If an accessible superclass method is static, then any method with the same signature in a subclass must also be static. If a superclass method is public, then the overriding method must also be public. If a superclass method is protected, then the overriding method must be protected or public. | The signature of a method is the name of the method and the number and types of the method parameters. The return type is not part of the method signature. An instance method declared in a subclass overrides an accessible superclass method with the same signature. A static method of a subclass hides--but does not override--an accessible superclass method with the same signature. A compile-time error is generated if a subclass contains a declaration of an instance method that shares the same signature as an accessible static method of the superclass. The modifiers, synchronized, native and strictfp, specify implementation details that the programmer is free to change in a subclass. Similarly, a subclass can override a concrete implementation of a method with an abstract method declaration. A subclass method may not have weaker access than the overridden superclass method. For example, a public method may not be overridden by a private method. However, a subclass method can provide greater access than a superclass method. For example, a protected method can be overridden by a public method. |