1Z0-811 Practice Test 33 — 15 Questions

Question 1

A developer is writing a batch processing application that reads a list of orders and processes each one. The orders are stored in an array of Order objects. The processing logic is complex and involves multiple conditional checks. The developer uses a for-each loop to iterate over the array. However, during testing, the application throws an IndexOutOfBoundsException when processing orders that have a status of "CANCELLED". The developer wants to skip the processing of cancelled orders but still record that the order was skipped in a log. The current code is:

for (Order order : orders) {
    if (order.getStatus().equals("CANCELLED")) {
        // Skip
    }
    // process order
    process(order);
    log(order);
}

The developer considers four options:

A. Change the for-each loop to a traditional for loop with an index and increment only when order is not cancelled.
B. Add a continue statement inside the if block.
C. Change the if condition to check for non-cancelled orders and wrap only the process(order) call inside the if block, leaving log(order) outside.
D. Use a while loop with an iterator and remove cancelled orders from the array.

Which option best solves the problem without modifying the array and while still logging all orders?

Accepted Answer

Change the if condition to check for non-cancelled orders and wrap only the process(order) call inside the if block, leaving log(order) outside.. Option A correctly logs all orders, including cancelled ones, by placing log(order) outside the if block. It processes only non-cancelled orders, avoiding the exception. Option C (continue) would skip both process and logging, failing to log cancelled orders. Option B unnecessarily complicates the loop and may still encounter index issues, while Option D modifies the array, which is prohibited. Therefore, A is the best choice.

Answer

Change the for-each loop to a traditional for loop with an index and increment only when order is not cancelled.

Answer

Add a continue statement inside the if block.

Answer

Use a while loop with an iterator and remove cancelled orders from the array.

Question 2

A developer wants to sort an array of primitive ints in descending order. Which approach will work without using third-party libraries?

Accepted Answer

Arrays.sort(arr); // then reverse the array manually. `Arrays.sort(int[])` sorts the array in ascending order, and then manually reversing the array yields descending order. The other options fail because `Arrays.parallelSort()` also sorts ascending, `Collections.reverseOrder()` requires an array of objects (not primitives), and a custom comparator cannot be used with primitive arrays in Java.

Answer

Arrays.parallelSort(arr);

Answer

Arrays.sort(arr, Collections.reverseOrder());

Answer

Arrays.sort(arr, (a,b) -> b - a);

Question 3

A developer is maintaining a Java backend service for order processing. The service uses a third-party library that throws a checked PaymentException when a payment fails. The current processOrder method catches Exception generically, logs the error, and returns null. The business requires that when a payment fails, the order status must be updated to 'FAILED' in the database, and a notification must be sent to the customer. However, due to the generic catch, these actions are not performed. The developer must modify the code to meet the business requirements without changing the external API of the class (i.e., the method signature must remain the same and must not throw any exceptions to the caller). Which course of action should the developer take?

Accepted Answer

In the catch block, check if the exception is an instance of PaymentException, then update the order status and send notification. Do not rethrow the exception.. The correct approach is Option D. The current code catches Exception generically, which prevents the specific handling of PaymentException. Option D catches Exception, checks if it is an instance of PaymentException, updates the order status and sends notification, and then does not rethrow the exception. This satisfies the business requirements without changing the method signature or propagating any exception to the caller. Option A is incorrect because rethrowing a RuntimeException still propagates an exception. Option B is incorrect because declaring throws Exception propagates the checked exception. Option C is incorrect because a finally block would execute even on success, leading to incorrect notifications and status updates.

Answer

Catch PaymentException specifically, update the order status and send notification, then throw a new RuntimeException to indicate failure.

Answer

Remove the try-catch block and declare the method with throws Exception, allowing the caller to handle payment failures.

Answer

Use a finally block to update the order status and send notification regardless of success or failure.

Question 4

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 5

Arrange the steps to declare and initialize a one-dimensional array in Java in the correct order.

Accepted Answer

Step 1: Declare array variable (e.g., int[] arr;), Step 2: Allocate memory using new keyword (e.g., arr = new int[5];), Step 3: Assign values to elements (e.g., arr[0] = 1; arr[1] = 2; ...).. The process involves declaring the array variable, then assigning it a new array or initializer, and optionally providing initial values.

Answer

Step 1: Allocate memory using new keyword, Step 2: Declare array variable, Step 3: Assign values.

Answer

Step 1: Assign values to elements, Step 2: Declare array variable, Step 3: Allocate memory.

Answer

Step 1: Declare array variable, Step 2: Assign values to elements, Step 3: Allocate memory.

Question 6

Arrange the steps to handle an exception using try-catch-finally in Java in the correct order.

Accepted Answer

try block, then catch block, then finally block. The try block contains risky code, catch handles the exception, and finally executes cleanup. The order is try, catch, then finally.

Answer

catch block, then try block, then finally block

Answer

finally block, then try block, then catch block

Answer

try block, then finally block, then catch block

Question 7

Arrange the steps to overload a method in Java in the correct order.

Accepted Answer

Define a method, then define another method with the same name but different parameters, then ensure the method signatures are unique, then call the method with arguments that match one of the signatures.. First define one method, then define another with same name but different parameters, ensure unique signatures, and then call with matching arguments.

Answer

Define a method, then ensure the method signatures are unique, then define another method with the same name but different parameters, then call the method with arguments.

Answer

Define another method with the same name but different parameters, then define a method, then ensure unique signatures, then call the method.

Answer

Call the method with arguments, then define a method, then define another method with the same name but different parameters, then ensure unique signatures.

Question 8

Evaluate the following expression: int x = 5; int y = (x > 5) ? 10 : 20; What is y?

Accepted Answer

20. The ternary operator `(x > 5) ? 10 : 20` evaluates the condition `x > 5`. Since `x` is 5, the condition is false, so the expression returns the value after the colon, which is 20. This value is assigned to `y`, making `y` equal to 20.

Answer

5

Answer

Compilation error

Answer

10

Question 9

What is the output of: int i = 1; i = i++; System.out.println(i);

Accepted Answer

1. In Java, the expression `i = i++` uses the post-increment operator, which first stores the current value of `i` (1) for the assignment, then increments `i` to 2, but the stored original value (1) is then assigned back to `i`. Thus, `i` remains 1, and the output is 1.

Answer

Compilation fails

Answer

0

Answer

2

Question 10

A developer writes: char c = 'A'; int i = c + 1; System.out.println(i); What is the output?

Accepted Answer

66. In Java, when a `char` is involved in arithmetic with an `int`, the `char` is promoted to its Unicode/ASCII numeric value. 'A' has the ASCII value 65, so `c + 1` becomes 66. The result is an `int`, and `System.out.println(i)` prints the integer 66.

Answer

B

Answer

Compilation error: cannot add char and int.

Answer

'A1'

Question 11

Consider a method that takes an int array and modifies it: public static void doubleArray(int[] arr) { for (int i = 0; i < arr.length; i++) { arr[i] *= 2; } }. What is the output of: int[] nums = {1, 2, 3}; doubleArray(nums); System.out.println(nums[1]);

Accepted Answer

4. The method `doubleArray` multiplies each element of the array by 2. The array `nums` is passed by reference, so modifications inside the method affect the original array. After execution, `nums[1]` (originally 2) becomes 4, which is printed.

Answer

8

Answer

2

Answer

3

Question 12

A developer needs to handle a specific checked exception, FileNotFoundException, but also wants to catch any other IOException that might occur. Which catch block ordering is correct?

Accepted Answer

catch (FileNotFoundException e) first, then catch (IOException e).. Checked exceptions must be caught in order from most specific to most general. FileNotFoundException is a subclass of IOException, so it must be caught first; otherwise, the more specific catch block would be unreachable and cause a compilation error. This ordering ensures that the developer can handle the specific FileNotFoundException separately while still catching any other IOException in the second block.

Answer

Use a multi-catch: catch (FileNotFoundException | IOException e).

Answer

catch (IOException e) first, then catch (FileNotFoundException e).

Answer

Use a single catch (Exception e).

Question 13

A developer writes a method that takes a variable number of integer arguments and returns the maximum. Which method signature is correct?

Accepted Answer

public int max(int... numbers). The varargs syntax `int... numbers` allows a method to accept zero or more integer arguments, which are then treated as an array inside the method. This is the standard Java syntax for variable-length argument lists, enabling the developer to pass any number of `int` values and compute the maximum.

Answer

public int max(int[]... numbers)

Answer

public int max(int numbers)

Answer

public int max(int[] numbers)

Question 14

Arrange the steps to compile and run a Java program from the command line in the correct order.

Accepted Answer

Write code, Open terminal, Navigate to file directory, Compile with javac, Run with java. The correct order is to first write the code, then open terminal, navigate to the file location, compile with javac, and run with java.

Answer

Write code, Open terminal, Compile with javac, Navigate to file directory, Run with java

Answer

Open terminal, Write code, Navigate to file directory, Compile with javac, Run with java

Answer

Write code, Open terminal, Navigate to file directory, Run with java, Compile with javac

Question 15

Which approach does NOT create a new array that is independent of the original?

Accepted Answer

int[] copy = original;. Assigning one array variable to another does not create a new array; both variables reference the same array object.

Answer

int[] copy = Arrays.copyOf(original, original.length);

Answer

int[] copy = original.clone();

Answer

int[] copy = new int[original.length]; System.arraycopy(original, 0, copy, 0, original.length);