Java Programming - Language Fundamentals
- Language Fundamentals - General Questions
- Language Fundamentals - Finding the output
- int [] myScores [];
- char [] myChars;
- int [6] myScores;
- Dog myDogs [];
- Dog myDogs [7];
(1), (2), and (4) are legal array declarations. With an array declaration, you can place the brackets to the right or left of the identifier. Option A looks strange, but it's perfectly legal to split the brackets in a multidimensional array, and place them on both sides of the identifier. Although coding this way would only annoy your fellow programmers, for the exam, you need to know it's legal.
(3) and (5) are wrong because you can't declare an array with a size. The size is only needed when the array is actually instantiated (and the JVM needs to know how much space to allocate for the array, based on the type of array and the size).
public interface Foo
{
int k = 4; /* Line 3 */
}
- final int k = 4;
- public int k = 4;
- static int k = 4;
- abstract int k = 4;
- volatile int k = 4;
- protected int k = 4;
(1), (2) and (3) are correct. Interfaces can have constants, which are always implicitly public, static, and final. Interface constant declarations of public, static, and final are optional in any combination.
Option B is the legal way to declare and initialize an array with five elements.
Option A is wrong because it shows an example of instantiating a class named Array, passing the integer value 5 to the object's constructor. If you don't see the brackets, you can be certain there is no actual array object! In other words, an Array object (instance of class Array) is not the same as an array object.
Option C is wrong because it shows a legal array declaration, but with no initialization.
Option D is wrong (and will not compile) because it declares an array with a size. Arrays must never be given a size when declared.
- char c1 = 064770;
- char c2 = 'face';
- char c3 = 0xbeef;
- char c4 = \u0022;
- char c5 = '\iface';
- char c6 = '\uface';
(1), (3), and (6) are correct. char c1 = 064770; is an octal representation of the integer value 27128, which is legal because it fits into an unsigned 16-bit integer. char c3 = 0xbeef; is a hexadecimal representation of the integer value 48879, which fits into an unsigned 16-bit integer. char c6 = '\uface'; is a Unicode representation of a character.
char c2 = 'face'; is wrong because you can't put more than one character in a char literal. The only other acceptable char literal that can go between single quotes is a Unicode value, and Unicode literals must always start with a '\u'.
char c4 = \u0022; is wrong because the single quotes are missing.
char c5 = '\iface'; is wrong because it appears to be a Unicode representation (notice the backslash), but starts with '\i' rather than '\u'.
Option A is correct. A public access modifier is acceptable. The method prototypes in an interface are all abstract by virtue of their declaration, and should not be declared abstract.
Option B is wrong. The final modifier means that this method cannot be constructed in a subclass. A final method cannot be abstract.
Option C is wrong. static is concerned with the class and not an instance.
Option D is wrong. protected is not permitted when declaring a method of an interface. See information below.
Member declarations in an interface disallow the use of some declaration modifiers; you cannot use transient, volatile, or synchronized in a member declaration in an interface. Also, you may not use the private and protected specifiers when declaring members of an interface.