1Z0-811 Control Flow and Loops Practice Test 3 — 15 Questions

Question 1

A programmer wants to iterate over a list of strings and print each that starts with 'A'. Which loop construct is best suited?

Accepted Answer

Enhanced for loop. The enhanced for loop (for-each) is best suited because it provides a clean, concise syntax for iterating over a collection like a List<String> without needing an explicit index or iterator. It directly yields each element, allowing a simple if-statement to check if the string starts with 'A' and print it, making the code more readable and less error-prone.

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Do-while loop

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Traditional for loop with index

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While loop with iterator

Question 2

A novice developer wrote a condition: if (x = 10) { ... } What is the result?

Accepted Answer

Compilation error. In Java, the assignment operator `=` is used to assign a value, not to compare values. The condition `if (x = 10)` attempts to assign 10 to `x` within an `if` statement, which is not a boolean expression. Java requires the condition in an `if` statement to evaluate to a `boolean`, so this code will not compile. Option D is correct because the compiler will report an error, typically stating 'incompatible types: int cannot be converted to boolean'.

Answer

The condition always evaluates to true

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It executes the block if x equals 10

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Runtime exception thrown

Question 3

Which of the following scenarios demonstrates the most appropriate use of a continue statement?

Accepted Answer

Skipping the current iteration and moving to the next when a condition is met. The `continue` statement in Java is specifically designed to skip the remaining code in the current iteration of a loop and proceed directly to the next iteration. This is the most appropriate use case, as it allows you to bypass certain iterations based on a condition without breaking out of the loop entirely.

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Restarting the loop from the beginning

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Implementing fall-through in a switch statement

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Exiting a loop early when a condition is met

Question 4

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

Accepted Answer

It can be used with char variables.. Options A and C are correct. A: Switch supports char, int, short, byte, String, and enum types, so char is valid. B is false because the break statement is optional; without it, execution falls through to the next case. C is true: the default case is optional. D is false because case labels must be compile-time constant expressions, not runtime expressions. E is false because long variables are not allowed in switch statements.

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The break statement is mandatory at the end of each case.

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Case labels can be runtime expressions.

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It can be used with long variables.

Question 5

Which THREE are valid loop constructs in Java? (Choose three.)

Accepted Answer

while (condition) { }. The `while` loop is a standard Java construct that repeatedly executes a block of code as long as the specified boolean condition evaluates to `true`. The syntax `while (condition) { }` is valid even with an empty body, as the condition is checked before each iteration.

Answer

repeat { } until (condition);

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loop (condition) { }

Question 6

Which TWO are best practices for using control flow statements? (Choose two.)

Accepted Answer

Use the enhanced for loop instead of the traditional for loop when iterating over arrays.. Options A and B are correct. A is correct because the enhanced for loop (for-each) is less error-prone and more readable when iterating over arrays or collections. B is correct because break statements can improve efficiency by allowing early exit from a loop when a condition is met, avoiding unnecessary iterations. C is wrong because deeply nested if-else blocks harm readability and maintainability; alternatives like switch or early returns are preferred. D is wrong because switch statements are often more readable and efficient than long else-if chains for multi-way branches based on a single value. E is wrong because Java does not support goto statements; its control flow uses structured constructs like break/continue with labels.

Answer

Use deeply nested if-else blocks to handle all possible conditions.

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Prefer multiple else-if chains over switch statements for multi-way branches.

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Use a goto statement to jump out of nested loops.

Question 7

A developer writes a loop that iterates over an array of integers. The loop should stop when it encounters a negative number. Which control flow construct best achieves this?

Accepted Answer

for loop with break inside if condition. A for loop with a break statement allows the developer to iterate over an array of integers and immediately exit the loop when a negative number is encountered. The break statement terminates the loop's execution unconditionally, making it the most direct and readable control flow construct for this requirement.

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do-while loop

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enhanced for loop with return

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while loop with continue

Question 8

A company's application uses a switch statement to handle different user roles. The code currently has a bug where after processing one role, it unintentionally executes the next role's logic. Which concept is being misused?

Accepted Answer

Missing break statements causing fall-through. In Java, a switch statement without break statements causes fall-through, where execution continues into subsequent case blocks even after a match is found. This is exactly the bug described: after processing one role, the code unintentionally executes the next role's logic because no break terminates the case.

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Incorrect default case

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Using enum in switch

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Using string in switch (Java 7+)

Question 9

A developer implements a loop that processes a list of transactions. The loop must ensure that at least one transaction is processed even if the list is empty. Which loop construct guarantees this?

Accepted Answer

do-while loop. The do-while loop is the correct choice because it guarantees that the loop body executes at least once, regardless of the condition. In Java, the do-while loop evaluates its boolean condition after executing the loop body, so even if the list is empty (e.g., size 0), the transaction processing code inside the loop will run once before the condition is checked.

Answer

while loop

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enhanced for loop

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for loop

Question 10

In a Java method, a developer needs to skip the current iteration and move to the next when a certain condition is met inside a for loop. Which statement should be used?

Accepted Answer

continue;. The `continue` statement in Java immediately skips the remaining code in the current iteration of a loop and proceeds to the next iteration. This is exactly what the developer needs when a condition is met inside a `for` loop to move to the next cycle without executing further statements in the current iteration.

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return;

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exit;

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break;

Question 11

A junior developer wrote a while loop that never terminates. What is the most likely cause?

Accepted Answer

The loop condition is always true. A while loop terminates only when its boolean condition evaluates to false. If the condition is always true, the loop will run indefinitely, causing an infinite loop. In Java, this typically happens when the loop variable is not updated or the condition logic is flawed.

Answer

The loop variable is incremented correctly

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The loop uses a for structure

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The loop body contains a break statement

Question 12

A developer needs to iterate over a 2D array row by row and exit early if a specific value is found in any cell. Which nested loop structure with control statements is most efficient?

Accepted Answer

Outer for with inner for, use labeled break. A labeled break allows the developer to exit both the inner and outer loops immediately when the target value is found. This is the most efficient approach for a row-by-row search in a 2D array, as it avoids unnecessary iterations after the value is located. Using a labeled break provides precise control over nested loop termination without requiring additional flags or method extraction.

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Outer for with inner for, use return

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Outer while with inner for, use continue

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Outer do-while with inner while, use break without label

Question 13

Which two statements about the break statement in Java are true?

Accepted Answer

break can be used inside a switch case. The break statement is used inside a switch case to terminate the switch block and prevent fall-through to subsequent cases. Without break, execution would continue into the next case, which is often unintended.

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break can be used without any enclosing loop

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break is used to skip to next iteration

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break exits the current loop iteration

Question 14

Which two control flow statements can be used to terminate a loop prematurely?

Accepted Answer

return. Options A (return) and D (break) are correct. The return statement terminates the enclosing method, thereby ending the loop. The break statement directly terminates the innermost loop. Option B (exit) is not a Java statement; System.exit() is a method but it is not a control flow statement for loop termination. Option C (System.gc()) is a garbage collection hint and does not affect loop control. Option E (continue) skips the current iteration but does not terminate the loop.

Answer

exit

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System.gc()

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continue

Question 15

Which three statements about the switch statement in Java are true?

Accepted Answer

a break statement is optional. Options A, B, and D are true. A: The break statement is optional; without it, execution falls through to the next case. B: char can be used as the switch expression type because char is an integer-compatible type. D: The default case executes when no other case matches. C is false because only one default case is allowed. E is false because boolean is not allowed as a switch expression.

Answer

the switch statement can have multiple default cases

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switch can use boolean as the expression type