Finding The Output

Question 16 :

What will be the output of the program?

for(int i = 0; i < 3; i++) 
{ 
    switch(i) 
    { 
        case 0: break; 
        case 1: System.out.print("one "); 
        case 2: System.out.print("two "); 
        case 3: System.out.print("three "); 
    } 
} 
System.out.println("done");


A). done
B). one two done
C). one two three done
D). one two three two three done
Answer : Option D

Explanation :

The variable i will have the values 0, 1 and 2.
When i is 0, nothing will be printed because of the break in case 0.
When i is 1, "one two three" will be output because case 1, case 2 and case 3 will be executed (they don't have break statements).
When i is 2, "two three" will be output because case 2 and case 3 will be executed (again no break statements).
Finally, when the for loop finishes "done" will be output.


Question 17 :

What will be the output of the program?

public class Test 
{  
    public static void main(String args[]) 
    { 
        int i = 1, j = 0; 
        switch(i) 
        { 
            case 2: j += 6; 
            case 4: j += 1; 
            default: j += 2; 
            case 0: j += 4; 
        } 
        System.out.println("j = " + j); 
    } 
}


A). j = 0
B). j = 2
C). j = 4
D). j = 6
Answer : Option D

Explanation :

Because there are no break statements, the program gets to the default case and adds 2 to j, then goes to case 0 and adds 4 to the new j. The result is j = 6.


Question 18 :

What will be the output of the program?

boolean bool = true; 
if(bool = false) /* Line 2 */
{
    System.out.println("a"); 
} 
else if(bool) /* Line 6 */
{
    System.out.println("b"); 
} 
else if(!bool) /* Line 10 */
{
    System.out.println("c"); /* Line 12 */
} 
else 
{
    System.out.println("d"); 
}


A). a
B). b
C). c
D). d
Answer : Option C

Explanation :

Look closely at line 2, is this an equality check (==) or an assignment (=). The condition at line 2 evaluates to false and also assigns false to bool. bool is now false so the condition at line 6 is not true. The condition at line 10 checks to see if bool is not true ( if !(bool == true) ), it isn't so line 12 is executed.


Question 19 :

What will be the output of the program?

public class Switch2 
{
    final static short x = 2;
    public static int y = 0;
    public static void main(String [] args) 
    {
        for (int z=0; z < 4; z++) 
        {
            switch (z) 
            {
                case x: System.out.print("0 ");
                default: System.out.print("def ");
                case x-1: System.out.print("1 ");  
                            break;
                case x-2: System.out.print("2 ");
            }
        }
    }
}


A). 0 def 1
B). 2 1 0 def 1
C). 2 1 0 def def
D). 2 1 0 def 1 def 1
Answer : Option D

Explanation :

When z == 0 , case x-2 is matched. When z == 1, case x-1 is matched and then the break occurs. When z == 2, case x, then default, then x-1 are all matched. When z == 3, default, then x-1 are matched. The rules for default are that it will fall through from above like any other case (for instance when z == 2), and that it will match when no other cases match (for instance when z==3).


Question 20 :

What will be the output of the program?

int i = 0, j = 5; 
tp: for (;;) 
    {
        i++;  
        for (;;) 
        {
            if(i > --j) 
            {
                break tp; 
            } 
        } 
        System.out.println("i =" + i + ", j = " + j);


A). i = 1, j = 0
B). i = 1, j = 4
C). i = 3, j = 4
D). Compilation fails.
Answer : Option D

Explanation :

If you examine the code carefully you will notice a missing curly bracket at the end of the code, this would cause the code to fail.