1Z0-829 Practice Test 8 — 10 Questions

Question 1

Which two statements about the java.time.Duration class are true? (Choose two.)

Accepted Answer

Duration can be negative.. The java.time.Duration class can represent negative durations, such as when the end instant is before the start instant in a Duration.between() call. Option C is correct because all classes in the java.time package, including Duration, are immutable and thread-safe by design, ensuring safe concurrent access without synchronization.

Answer

Duration supports units like months and years.

Answer

Duration.between(LocalDate.now(), LocalDate.now()) returns a Duration.

Answer

Duration uses a days-based representation.

Question 2

Which statement about Collection interface remove methods is correct?

Accepted Answer

Collection.remove(Object) removes the first occurrence and returns boolean.. The Collection interface's remove(Object) method removes the first occurrence of the specified element from the collection, if present, and returns true if the collection was modified (i.e., the element was found and removed). This behavior is defined in the Java Collections Framework and applies to all implementations of Collection, such as ArrayList and HashSet.

Answer

List.remove(int) removes element at index and returns the removed element.

Answer

Collection.remove(Object) removes all occurrences of the element.

Answer

Both B and C

Question 3

Which TWO statements about Arrays.asList() are true? (Select two.)

Accepted Answer

It returns a fixed-size list backed by the original array.. `Arrays.asList()` returns a fixed-size list backed by the original array, meaning the list's size cannot be changed (no add or remove operations allowed). Option E is correct because any modification to the returned list (e.g., setting an element) directly modifies the underlying array, and vice versa, as the list is a view of the array.

Answer

It supports adding and removing elements.

Answer

It returns a new ArrayList with a copy of the elements.

Answer

It can be used to convert an array to a mutable list if wrapped with new ArrayList<>().

Question 4

Which TWO are valid ways to create an immutable list in Java 17? (Choose two.)

Accepted Answer

Collections.unmodifiableList(new ArrayList<>(List.of("a", "b"))). `Collections.unmodifiableList()` wraps a mutable list in an unmodifiable view, preventing any structural modifications. Option D is correct because `List.copyOf()` creates an immutable list from an existing collection, throwing `NullPointerException` if any element is null. Both produce lists that cannot be modified after creation.

Answer

Arrays.asList("a", "b")

Answer

List.of(List.of("a", "b"))

Answer

new ArrayList<>(List.of("a", "b"))

Question 5

A developer creates a module `com.example.app` that requires `java.sql` and `com.example.util`. The module is compiled and packaged into a JAR. When launching the application with `java --module-path app.jar:lib --module com.example.app`, it fails with `java.lang.module.ResolutionException: Module com.example.util not found`. What is the most likely cause?

Accepted Answer

The module `com.example.util` is not in the module path.. The error `Module com.example.util not found` indicates that the module system cannot locate `com.example.util` on the module path. Since the command specifies `--module-path app.jar:lib`, the JAR for `com.example.util` must be present in the `lib` directory (or another directory on that path). If it is missing or not in the correct location, the module resolution fails. Option B correctly identifies that the module is simply not on the module path.

Answer

The module `com.example.util` is an automatic module and requires specific flags.

Answer

The module `com.example.util` is a named module but not exported.

Answer

The module `com.example.util` is on the classpath and not visible to module system.

Question 6

Consider: List list = new LinkedList<>(); list.add(10); list.add(20); list.add(0,5); System.out.println(list); What is the output?

Accepted Answer

[5,10,20]. The code creates a LinkedList and adds 10, then 20. The third call `list.add(0,5)` inserts 5 at index 0, shifting existing elements to the right. The resulting list is [5,10,20], so option B is correct.

Answer

[10,5,20]

Answer

[10,20,5]

Answer

[5,10,20] but with type warning

Question 7

Given: TreeSet set = new TreeSet<>(List.of(3,1,2)); set.add(2); System.out.println(set); What is the output?

Accepted Answer

[1,2,3]. E is correct because TreeSet maintains elements in their natural sorted order (ascending for integers). The list [3,1,2] is sorted to [1,2,3], and adding 2 again has no effect since TreeSet does not allow duplicates. The output is [1,2,3].

Answer

[1,2]

Answer

[1,3,2]

Answer

[3,1,2]

Answer

UnsupportedOperationException

Question 8

Which of the following is a checked exception in Java?

Accepted Answer

SQLException. SQLException is a checked exception because it extends Exception directly (not RuntimeException). Checked exceptions must be either caught with a try-catch block or declared in the method signature using 'throws'. SQLException is thrown by JDBC API methods when database access errors occur, forcing the developer to handle potential SQL failures at compile time.

Answer

NullPointerException

Answer

ArrayIndexOutOfBoundsException

Answer

IllegalArgumentException

Question 9

What happens when a finally block throws an exception?

Accepted Answer

The exception from the try block is suppressed and the finally exception is reported.. When a finally block throws an exception, the JVM suppresses the exception that was thrown from the try block (if any) and propagates the exception thrown from the finally block. This behavior is defined in the Java Language Specification (JLS §14.20.2) and ensures that the finally block's exception takes precedence, as the finally block is executed after the try block completes abruptly.

Answer

The JVM logs both exceptions and then terminates the thread.

Answer

The exception from the try block is propagated and the finally exception is ignored.

Answer

Both exceptions are reported as suppressed exceptions of a new exception.

Question 10

A developer wants to ensure that a block of code always executes regardless of whether an exception occurs or not, and that any exception thrown in the block is not swallowed. Which construct should be used?

Accepted Answer

try-finally. The try-finally construct ensures that the finally block always executes after the try block, regardless of whether an exception occurs, and it does not catch or swallow any exception. This meets the requirement of guaranteed execution without suppressing the exception, as the exception propagates up the call stack.

Answer

try-catch with empty catch block

Answer

try-catch-finally with catch that rethrows the exception

Answer

try-with-resources without catch