Language Fundamentals Questions and Answers updated daily – Java



10 Language Fundamentals Questions and answers section with explanation for various online exam preparation, various interviews, Java Language Fundamentals online test. Language Fundamentals Questions with detailed description, explanation will help you to master the topic.

Language Fundamentals Questions

1.
Which three are valid declarations of a float?

float f1 = -343;
float f2 = 3.14;
float f3 = 0x12345;
float f4 = 42e7;
float f5 = 2001.0D;
float f6 = 2.81F;



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Correct Ans:1,3,6
Explanation:
(1) and (3) are integer literals (32 bits), and integers can be legally assigned to floats (also 32 bits). (6) is correct because (F) is appended to the literal, declaring it as a float rather than a double (the default for floating point literals).

(2), (4),and (5) are all doubles.


2.
What is the numerical range of a char?



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Correct Ans:0 to 65535
Explanation:
A char is really a 16-bit integer behind the scenes, so it supports 216 (from 0 to 65535) values.


3.
Which three are valid declarations of a char?

char c1 = 064770;
char c2 = 'face';
char c3 = 0xbeef;
char c4 = u0022;
char c5 = 'iface';
char c6 = 'uface';



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Correct Ans:1,3,6
Explanation:
(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'.


4.
public interface Foo 
    int k = 4; /* Line 3 */
}
Which three piece of codes are equivalent to 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;



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Correct Ans:1,2,3
Explanation:
(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.


5.
Which three are legal array declarations?

int [] myScores [];
char [] myChars;
int [6] myScores;
Dog myDogs [];
Dog myDogs [7];



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Correct Ans:1,2,4
Explanation:
(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).


6. Which is a valid keyword in java?



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Correct Ans:interface
Explanation:
interface is a valid keyword.

Option B is wrong because although "String" is a class type in Java, "string" is not a keyword.

Option C is wrong because "Float" is a class type. The keyword for the Java primitive is float.

Option D is wrong because "unsigned" is a keyword in C/C++ but not in Java.


7. Which is a reserved word in the Java programming language?



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Correct Ans:native
Explanation:
The word "native" is a valid keyword, used to modify a method declaration.

Option A, D and E are not keywords. Option C is wrong because the keyword for subclassing in Java is extends, not 'subclasses'.


8. Which will legally declare, construct, and initialize an array?



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Correct Ans:int [] myList = {"4", "3", "7"};
Explanation:
The only legal array declaration and assignment statement is Option D

Option A is wrong because it initializes an int array with String literals.

Option B is wrong because it use something other than curly braces for the initialization.

Option C is wrong because it provides initial values for only one dimension, although the declared array is a two-dimensional array.


9. Which one of these lists contains only Java programming language keywords?



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Correct Ans:goto, instanceof, native, finally, default, throws
Explanation:
All the words in option B are among the 49 Java keywords. Although goto reserved as a keyword in Java, goto is not used and has no function.

Option A is wrong because the keyword for the primitive int starts with a lowercase i.

Option C is wrong because "virtual" is a keyword in C++, but not Java.

Option D is wrong because "constant" is not a keyword. Constants in Java are marked static and final.

Option E is wrong because "include" is a keyword in C, but not in Java.


10.
Which four options describe the correct default values for array elements of the types indicated?

int -> 0
String -> "null"
Dog -> null
char -> 'u0000'
float -> 0.0f
boolean -> true



SHOW ANSWER
Correct Ans:1,3,4,5
Explanation:
(1), (3), (4), (5) are the correct statements.

(2) is wrong because the default value for a String (and any other object reference) is null, with no quotes.

(6) is wrong because the default value for boolean elements is false.



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