1Z0-811 Control Flow and Loops Practice Test 2 — 15 Questions

Question 1

A developer needs to iterate over an array of integers and compute the sum of its elements. Which loop construct is most appropriate for this task?

Accepted Answer

Enhanced for loop. The enhanced for loop (for-each) is the most appropriate construct for iterating over an array of integers to compute a sum because it provides a concise, read-only traversal without needing an explicit index or iterator. It directly accesses each element in sequence, reducing boilerplate and the risk of off-by-one errors, which is ideal for aggregation operations like summation.

Answer

while loop

Answer

switch statement

Answer

do-while loop

Question 2

A programmer writes a switch statement to handle different cases. The code compiles and runs, but the output is unexpected: 'A' prints when the input is 'B'. Which is the most likely cause?

Accepted Answer

A break statement is missing after the case 'B'.. In a switch statement, when a case matches, execution continues sequentially through subsequent cases (fall-through) unless a break statement is encountered. If case 'B' lacks a break, after executing its code, the program falls through to the code for case 'A' (or the next case), printing 'A' even though the input was 'B'. This is the classic fall-through behavior in Java.

Answer

The switch variable type is char but should be String.

Answer

The switch statement is missing a default case.

Answer

The default case is executed instead of the matched case.

Question 3

In a nested loop structure, a developer wants to exit completely from the outer loop when a certain condition is met inside the inner loop. Which approach is correct?

Accepted Answer

Use a labeled break statement (e.g., break outerLabel;).. Java's labeled break statement allows a developer to specify an outer loop label and break out of that loop entirely from within an inner loop. This is the only control flow mechanism designed to exit multiple nested loops at once, as a plain break only exits the innermost loop.

Answer

Use a return statement within the inner loop.

Answer

Use a continue statement with a label.

Answer

Use a break statement inside the inner loop.

Question 4

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

Accepted Answer

while loop. The correct answers are A (while loop), B (for loop), and E (do-while loop) because all three are valid loop constructs in Java. The while loop repeats as long as a condition is true, the for loop provides a compact iteration mechanism, and the do-while loop guarantees at least one execution.

Answer

switch statement

Answer

if statement

Question 5

Which THREE of the following are valid types that can be used as a switch expression in Java (as of Java 8)?

Accepted Answer

String. In Java 8, a switch expression can use `String`, `char`, and `int` as valid types. `String` was added in Java 7, and `char` and `int` are among the original primitive types supported. `long` and `boolean` are not allowed because `long` is a 64-bit type not supported by the switch statement's underlying `tableswitch` or `lookupswitch` bytecode instructions, and `boolean` has only two values, making it unsuitable for switch's multi-branch logic.

Answer

long

Answer

boolean

Question 6

Which TWO statements about the enhanced for loop (for-each) are correct?

Accepted Answer

It can iterate over any object that implements the Iterable interface.. The enhanced for loop (for-each) works with any object that implements the Iterable interface, which includes all Collection classes (like ArrayList, HashSet) and arrays. This allows the loop to iterate over elements without needing an explicit iterator or index, relying on the iterator() method provided by the Iterable contract.

Answer

It can be used to modify the elements of an array.

Answer

It can only be used with collections.

Answer

It provides an implicit counter variable.

Question 7

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 iterates from i=0 to i=4. When i equals 2, the continue statement skips the rest of the loop body, so the increment of count is not executed for i=2. For the remaining four iterations (i=0,1,3,4), count is incremented, resulting in a final value of 4. Option B is incorrect because the loop code is syntactically valid and compiles without error. Option C would be correct if a break statement were used instead of continue. Option D is incorrect because the loop runs the full 5 iterations, incrementing count 4 times.

Answer

The loop does not compile.

Answer

5

Answer

2

Question 8

What is the output of the program?

Accepted Answer

Two Three. The switch statement matches the value 2, executing the case 2 block which prints 'Two'. Since there is no break statement, execution falls through to case 3, printing 'Three'. The default case is not executed because fall-through stops at the end of the switch block. Thus, the output is 'Two Three'.

Answer

Two

Answer

Two Three Default

Answer

Compilation fails because case 2 is missing a break.

Question 9

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 10

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 11

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. The most appropriate loop construct for this scenario is a for loop with a break statement. A for loop provides a concise way to iterate over an array by index, and the break statement allows the loop to terminate immediately once the target value is found, avoiding unnecessary iterations. While a while loop with a flag variable could also work, the for loop is more idiomatic and less error-prone. An enhanced for loop supports break as well, but it lacks access to the loop index, which may be needed. A do-while loop is not suitable because it guarantees at least one iteration even if the array is empty or the target is found early. Therefore, option D is correct.

Answer

While loop with a flag variable

Answer

Enhanced for loop with continue

Answer

Do-while loop

Question 12

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 13

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 14

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 15

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