Finding The Output

Question 6 :

What will be the output of the program?

public class CommandArgsTwo 
{
    public static void main(String [] argh) 
    {
        int x;
        x = argh.length;
        for (int y = 1; y <= x; y++) 
        {
            System.out.print(" " + argh[y]);
        }
    }
}
and the command-line invocation is
> java CommandArgsTwo 1 2 3


A). 0 1 2
B). 1 2 3
C). 0 0 0
D). An exception is thrown at runtime
Answer : Option D

Explanation :

An 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 < = someArray.length.


Question 7 :

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);
        }
    }
    }
}


A). 7
B). 9
C). 11
D). 13
E). Compilation fails
Answer : Option C

Explanation :

The 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.


Question 8 :

What will be the output of the program?

public class X 
{
    public static void main(String [] args) 
    {
        String names [] = new String[5];
        for (int x=0; x < args.length; x++)
            names[x] = args[x];
        System.out.println(names[2]);
    }
}
and the command line invocation is
> java X a b


A). names
B). null
C). Compilation fails
D). An exception is thrown at runtime
Answer : Option B

Explanation :

The 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.