Language Fundamentals(Computer Science > Java Program ) Questions and Answers
Explanation:-
Answer: Option B. -> nullThe names array is initialized with five null elements. Then elements 0 and 1
are assigned the String values "a" and "b" respectively (the command-line
arguments passed to main). Elements of names array 2, 3, and 4 remain
unassigned, so they have a value of null.
In the given program, how many lines of output will be produced?
public class Test
{
public static void main(String [] args)
{
int [] [] [] x = new int [3] [] [];
int i, j;
x[0] = new int[4][];
x[1] = new int[2][];
x[2] = new int[5][];
for (i = 0; i < x.length; i++)
{
for (j = 0; j < x[i].length; j++)
{
x[i][j] = new int [i + j + 1];
System.out.println("size = " + x[i][j].length);
}
}
}
}
Explanation:-
Answer: Option C. -> 11The loops use the array sizes (length).
It produces 11 lines of output as given below.
D:Java>javac Test.java
D:Java>java Test
size = 1
size = 2
size = 3
size = 4
size = 2
size = 3
size = 3
size = 4
size = 5
size = 6
size = 7
Therefore, 11 is the answer.
Explanation:-
Answer: Option D. -> An exception is thrown at runtimeAn exception is thrown because at some point in (System.out.print(" " + argh[y]);),
the value of x will be equal to y, resulting in an attempt to access an index out of
bounds for the array. Remember that you can access only as far as length - 1,
so loop logical tests should use x < someArray.length as opposed to x < = some
Array.length.
Explanation:-
Answer: Option C. -> Compilation fails.The word "signed" is not a valid modifier keyword in the Java language. All number
primitives in Java are signed. Hence the Compilation will fails.
Explanation:-
Answer: Option D. -> An exception is thrown at runtimeThe second dimension of the array referenced by theDogs has not been
initialized. Attempting to access an uninitialized object element (System.
out.println(theDogs[2][0].toString());) raises a NullPointerException.
Explanation:-
Answer: Option D. -> The code does not run.Option D is correct. A runtime error will occur owning to the main method of the
code fragment not being declared static:
Exception in thread "main" java.lang.NoSuchMethodError: main
The Java Language Specification clearly states: "The main method must be
declared public, static, and void. It must accept a single argument that is an
array of strings."
Explanation:-
Answer: Option D. -> An exception is thrown at runtime.An exception is thrown because in the code String s4 = args[4];, the array index
(the fifth element) is out of bounds. The exception thrown is the cleverly named
ArrayIndexOutOfBoundsException
Explanation:-
Answer: Option A. -> String s1 = null;Option A sets the String reference to null.
Option B is wrong because null cannot be in single quotes.
Option C is wrong because there are multiple characters between the
single quotes ('abc').
Option D is wrong because you can't cast a char (primitive) to a String
(object).
What will be the output of the program?
public class CommandArgsThree
{
public static void main(String [] args)
{
String [][] argCopy = new String[2][2];
int x;
argCopy[0] = args;
x = argCopy[0].length;
for (int y = 0; y < x; y++)
{
System.out.print(" " + argCopy[0][y]);
}
}
}
and the command-line invocation is
> java CommandArgsThree 1 2 3
Explanation:-
Answer: Option D. -> 1 2 3In argCopy[0] = args;, the reference variable argCopy[0], which was referring to
an array with two elements, is reassigned to an array (args) with three elements.