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

Question 1

Which THREE of the following are valid loop constructs in Java?

Accepted Answer

while loop. The while loop (A) is a valid Java loop construct that repeatedly executes a statement or block as long as its boolean condition remains true, checking the condition before each iteration. The for loop (B) is also valid, providing a compact header with initialization, condition, and update expressions to control iteration, including the enhanced for-each form for arrays and Iterables. The do-while loop (E) is valid as well, executing its body at least once and then repeating while its boolean condition is true, since the condition is evaluated after the body. The switch statement (C) is a selection/branching construct, not a loop, and the if statement (D) is a conditional branching construct, so neither repeats execution on its own and neither belongs among Java's loop constructs.

Answer

switch statement

Answer

if statement

Question 2

int count = 0;
for (int i = 0; i < 5; i++) {
    if (i == 2) {
        continue;
    }
    count++;
}
System.out.println(count);

What is the output of the program?

Accepted Answer

4. The loop runs i from 0 to 4. When i equals 2, the continue statement skips the rest of the loop body, so count++ is not executed for that iteration. For the other four iterations (i = 0, 1, 3, 4), count is incremented, giving a final value of 4.

Answer

The loop does not compile.

Answer

5

Answer

2

Question 3

What is printed by the program?

```java
for (int i = 0; i < 2; i++) {
    for (int j = 0; j < 3; j++) {
        System.out.print(i + "," + j + " ");
        if (i == 1) break;
    }
}
```

Accepted Answer

0,0 0,1 0,2 1,0. The program uses nested for loops. The outer loop runs with i from 0 to 1 (inclusive). For each i, the inner loop runs with j from 0 to 2 (inclusive). However, the inner loop contains a break statement that executes when i equals 1, causing the inner loop to terminate after printing the first pair for i=1 (1,0). Thus, the output is: 0,0 0,1 0,2 1,0. The outer loop then increments i to 2, but the condition i < 2 fails, so the program ends.

Answer

0,0 0,1 0,2

Answer

0,0 0,1 0,2 1,0 1,1 1,2 2,0 2,1 2,2

Answer

0,0 0,1 0,2 1,0 1,1

Question 4

A developer writes the following code: if (score >= 90) { grade = 'A'; } else if (score >= 80) { grade = 'B'; } else if (score >= 70) { grade = 'C'; } else { grade = 'D'; } What is the value of grade if score is 75?

Accepted Answer

'C'. The code uses a cascading if-else-if structure that evaluates conditions from top to bottom. When score is 75, the first condition (score >= 90) is false, the second (score >= 80) is false, and the third (score >= 70) is true, so grade is assigned 'C'. The else block is only reached if all prior conditions are false.

Answer

'B'

Answer

'D'

Answer

'A'

Question 5

A team is implementing a search algorithm that iterates over an array of integers. The loop should stop as soon as the target value is found. Which loop construct is most appropriate?

Accepted Answer

For loop with break. A for loop with a break statement is the most appropriate construct because it allows iteration over the array with an explicit exit condition the moment the target value is found. The break statement immediately terminates the loop, avoiding unnecessary iterations and clearly expressing the early-exit intent. This is idiomatic Java and matches the requirement to stop as soon as the target is located.

Answer

While loop with a flag variable

Answer

Enhanced for loop with continue

Answer

Do-while loop

Question 6

Consider a method that processes a two-dimensional array (matrix). It uses nested for loops. The inner loop uses a label 'outer' to break out of the outer loop. Under what condition is this label beneficial?

Accepted Answer

When you need to exit the outer loop from inside the inner loop. In Java, a labeled break statement allows you to exit an outer loop from within a nested inner loop. The label 'outer' is placed before the outer loop, and when the break outer; statement executes inside the inner loop, control jumps directly to the statement after the outer loop. This is beneficial specifically when you need to terminate the entire outer loop based on a condition detected inside the inner loop.

Answer

When you want to skip the current iteration of the outer loop

Answer

When you have a single loop and need to break to a specific point

Answer

When you want to exit the inner loop only

Question 7

A developer writes a switch statement that checks the day of the week. The code uses fall-through to handle weekdays. What happens if a case does not end with a break?

Accepted Answer

Execution continues to the next case. In Java, when a case in a switch statement does not end with a break statement, execution falls through to the next case, continuing until a break is encountered or the switch block ends. This is known as fall-through behavior, which the developer intentionally uses to handle weekdays collectively.

Answer

The default case is executed

Answer

Compilation error

Answer

Runtime exception is thrown

Question 8

A program needs to read user input until 'quit' is entered. Which loop ensures that the condition is evaluated after executing the body at least once?

Accepted Answer

do-while loop. The do-while loop is the only loop construct in Java that guarantees the loop body executes at least once before the condition is evaluated. This is because the condition is checked after the body runs, making it ideal for scenarios like reading user input until a sentinel value like 'quit' is entered, where the first input must be processed before checking.

Answer

enhanced for loop

Answer

for loop

Answer

while loop

Question 9

A developer writes the following code: for (int i = 0; i < 5; i++) { for (int j = i; j < 5; j++) { System.out.print(j); } } How many times does the inner loop execute in total?

Accepted Answer

15. The outer loop runs with i from 0 to 4 (5 iterations). For each i, the inner loop runs from j = i to j < 5, so the number of inner iterations is 5 - i. Summing these: 5 + 4 + 3 + 2 + 1 = 15. Thus, the inner loop executes 15 times in total.

Answer

5

Answer

10

Answer

20

Question 10

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.

Answer

Do-while loop

Answer

Traditional for loop with index

Answer

While loop with iterator

Question 11

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

Answer

It executes the block if x equals 10

Answer

Runtime exception thrown

Question 12

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.

Answer

Restarting the loop from the beginning

Answer

Implementing fall-through in a switch statement

Answer

Exiting a loop early when a condition is met

Question 13

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

Accepted Answer

It can be used with char variables.. Option A is correct because Java's switch statement supports char (and Character) values, since char is one of the integral types permitted in switch expressions. Option C is correct because the default case is optional; a switch can omit it, and if no case matches, execution simply falls through without entering any branch. Option B is incorrect because break is not mandatory—omitting it causes fall-through, which is legal (though often unintended). Option D is incorrect because case labels must be compile-time constant expressions, not runtime expressions. Option E is incorrect because long (and Long) values are not permitted in a switch statement; only int-compatible types, char, byte, short, String, and enums are allowed.

Answer

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

Answer

Case labels can be runtime expressions.

Answer

It can be used with long variables.

Question 14

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);

Answer

loop (condition) { }

Question 15

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.. Option A is correct because the enhanced for loop (for-each) eliminates the index variable and off-by-one errors, making iteration over arrays and Iterable collections clearer and less error-prone when the index itself is not needed. Option B is correct because a break statement provides a clean, readable way to terminate a loop as soon as its exit condition is satisfied, avoiding unnecessary iterations and often simplifying loop logic. Option C is not a best practice since deeply nested if-else blocks hurt readability and maintainability; guard clauses or early returns are preferred. Option D is wrong because switch statements are generally clearer and more efficient than long else-if chains for multi-way branching on a single value. Option E is wrong because Java has no goto statement (it is a reserved but unused keyword), and labeled break is the proper construct for exiting nested loops.

Answer

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

Answer

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

Answer

Use a goto statement to jump out of nested loops.