1Z0-811 Control Flow and Loops — Timed 10 Questions

Question 1

A developer writes a loop to iterate over an array of integers. The loop must sum all elements and stop early if the sum exceeds 100. Which control flow construct should be used?

Accepted Answer

for(int i=0; i<arr.length; i++) { sum += arr[i]; if(sum > 100) break; }. Option B is correct because it uses a for loop with an index variable to iterate over the array, and includes an if statement with a break to exit the loop early when the sum exceeds 100. This ensures all elements are summed until the condition is met, and the loop stops immediately, preventing unnecessary iterations.

Answer

while(true) { sum += arr[i]; i++; }

Answer

do { sum += arr[i]; i++; } while(i<arr.length && sum <= 100);

Answer

for(int val : arr) { sum += val; if(sum > 100) break; }

Question 2

Which loop is guaranteed to execute its body at least once?

Accepted Answer

do-while loop. The do-while loop is a post-test loop, meaning the condition is evaluated after the loop body executes. This guarantees that the body runs at least once, regardless of whether the condition is initially true or false. In Java, the do-while loop syntax is `do { ... } while (condition);`.

Answer

repeat-until loop

Answer

while loop

Answer

for loop

Question 3

A developer needs to implement a menu-driven program that repeatedly displays options, reads input, and processes the choice until the user selects 'Exit'. Which loop structure and control flow is most appropriate?

Accepted Answer

do-while loop with switch statement. Option C is correct because a do-while loop guarantees at least one iteration, which is ideal for menu-driven programs where the menu must be displayed before any input is processed. The switch statement provides a clean, readable way to handle multiple discrete choices (like menu options) compared to a chain of if-else statements, and it aligns with Java's control flow best practices for such scenarios.

Answer

for loop with break condition and nested if-else

Answer

for(;;) loop with if-else chain

Answer

while(true) loop with if-else chain

Question 4

What is the output of the following code?

int i = 0;
while (i < 5) {
    if (i == 3) {
        i++;
        continue;
    }
    System.out.print(i + " ");
    i++;
}

Accepted Answer

0 1 2 4. The while loop iterates while i < 5. When i equals 3, the if condition triggers, incrementing i to 4 and then using continue to skip the print statement for that iteration. Thus, 3 is never printed, and the loop prints 0, 1, 2, and then 4 before i becomes 5 and the loop ends.

Answer

0 1 2 3

Answer

0 1 2 4 5

Answer

0 1 2 3 4

Question 5

Which statement about the for-each loop in Java is true?

Accepted Answer

It cannot remove elements from a collection during iteration without additional logic.. Option A is correct because the for-each loop (enhanced for loop) in Java does not expose the iterator or index, so you cannot safely remove elements from a collection during iteration without using an explicit iterator and its remove() method. Attempting to remove directly will throw a ConcurrentModificationException.

Answer

It can modify the array elements.

Answer

It can iterate in reverse order.

Answer

It cannot be used with arrays.

Question 6

A developer writes: for(int i=0; i<10; i++) { if(i%2==0) continue; System.out.print(i); }. What is the output?

Accepted Answer

13579. The loop iterates from i=0 to i=9. The `continue` statement skips the rest of the loop body when the condition `i%2==0` is true (i.e., when i is even). Therefore, only odd values of i (1, 3, 5, 7, 9) are printed, producing the output '13579'. Option B is correct.

Answer

0123456789

Answer

02468

Answer

123456789

Question 7

Which loop best suits a scenario where the number of iterations is unknown and depends on user input?

Accepted Answer

while loop. The while loop is best when the number of iterations is unknown and depends on user input because it evaluates a boolean condition before each iteration, allowing the loop to continue as long as the condition remains true. This is ideal for scenarios like reading user input until a sentinel value is entered, where the exact number of iterations cannot be predetermined.

Answer

for loop

Answer

for-each loop

Answer

do-while loop

Question 8

Which TWO statements are true about the switch statement in Java? (Choose two.)

Accepted Answer

The default case is optional.. Option D is correct because the default case in a switch statement is optional; if no case matches and no default is present, the switch simply does nothing. Option E is correct because Java supports switch on String objects (since Java 7), comparing the switch expression against case labels using the String.equals() method.

Answer

It can be used with boolean expressions.

Answer

The default case must be placed at the end of the switch block.

Answer

Without a break statement, execution falls through to the next case.

Question 9

Which THREE statements are true about the break and continue statements in Java? (Choose three.)

Accepted Answer

A labeled break can be used to exit an outer loop.. Option A is correct because a labeled break in Java allows you to specify a label on an outer loop and then use 'break label;' to exit that outer loop directly, not just the innermost loop. This is useful for breaking out of nested loops when a condition is met in an inner loop.

Answer

The continue statement can be used to exit a loop entirely.

Answer

The break statement cannot be used outside a loop.

Question 10

What is the output of the code?

Accepted Answer

0 1 3 4. The code uses a for loop with an if condition that skips the iteration when the loop variable equals 2 using the continue statement. Therefore, the loop prints 0, 1, 3, and 4, but not 2. Option D correctly lists this output.

Answer

0 1 2 3 4

Answer

1 3 4

Answer

0 1 2 3