Control Statements : MCQs & PYQs with Explanation

Option D

In traditional Java switch statements, the switch expression can use integral types such as byte, short, char, and int, as well as their corresponding wrapper types. Java also supports String and enum values in switch. However, double is not supported as a switch expression type.
E.g.: 1
int x = 2;
switch (x) 
{
    case 1:
        System.out.println("One");
        break;
    case 2:
        System.out.println("Two");
        break;
}
E.g.: 2
char grade = 'A';
switch (grade) 
{
    case 'A':
        System.out.println("Excellent");
        break;
}
E.g.: 3
String day = "Monday";
switch (day) 
{
    case "Monday":
        System.out.println("Start of week");
        break;
}
E.g.: 4
double value = 2.5;
switch (value) // Compile-Time Error
{
    case 2.5:
        System.out.println("Two point five");
        break;
}

Option B

In Java, the switch statement is used to select one block of code based on the value of an expression. When the value of the expression matches a case, execution starts from that case and continues with the following cases until a break statement or the end of the switch block is reached.
In the given code, the value of a is 2. Java first checks the cases. case 1 does not match because a is 2. Therefore, execution starts from case 2, where B is printed.
There is no break statement after case 2, so Java does not stop there. It continues directly to case 3 and prints C.
Therefore, the output is BC.

Option A

In Java, a for loop consists of three parts, initialization, condition, and update. In this question, the loop uses the post-increment operator (j++) and the logical AND operator (&&). 
The post-increment operator uses the current value of a variable in the expression and increments it afterward. The && operator evaluates the second condition only when the first condition is true.

Option A

In Java, the break statement is a control-flow statement used to immediately terminate the execution of the nearest loop or switch statement. 
When the break statement is executed inside a loop, the program comes out of that loop and continues executing the statement written after the loop.
E.g.:
class Example 
{
    public static void main(String args[]) 
    {
        for (int i=1; i<=5; i++) 
        {
            if (i==3) 
            {
                break;
            }
            System.out.println(i);
        }
        System.out.println("Loop Ended.");
    }
}
OUTPUT
1
2
Loop Ended.

Option B

In Java, the continue statement is used inside a loop to skip the remaining statements of the current iteration and move to the next iteration of the loop. It does not terminate the entire loop, it only skips one iteration.
In the given code, the loop starts with i=0 and continues while i<5.

• When i=0, the condition i==2 is false, so 0 is printed.
• When i=1, the condition is false, so 1 is printed.
• When i=2, the condition becomes true. The continue statement is executed, so the System.out.print(i) statement is skipped. Therefore, 2 is not printed.
• When i=3, the condition is false, so 3 is printed.
• When i=4, the condition is false, so 4 is printed.
• After that, i becomes 5, the condition i<5 becomes false, and the loop ends.

Therefore, the output is 0134.
Note:
The important difference is that continue skips the current iteration, whereas break terminates the loop completely.
For example, if continue were replaced with break:
for (int i=0; i<5; i++) 
{
    if (i==2)
        break;
    System.out.print(i);
}
The output would be 01 because the loop would terminate as soon as i becomes 2.

Option B

In Java, the do-while loop guarantees that its loop body is executed at least once, because the condition is checked after the loop body is executed. Therefore, even if the condition is false initially, the statements inside the loop will execute one time.
Syntax:
do
{
    // statements
}
while (condition);
E.g.:
class Example
{
    public static void main(String args[])
    {
        int i=10;
        do
        {
            System.out.println("Loop Executed");
        }
        while (i<5);
    }
}
OUTPUT
Loop Executed