1Z0-829 Matching — 10 Questions

Question 1

Match each functional interface to its abstract method signature.

Accepted Answer

Predicate: boolean test(T). The correct matches are Predicate -> boolean test(T), Consumer -> void accept(T), Supplier -> T get(). Common confusions involve swapping method signatures between interfaces.

Answer

Predicate: T get()

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Consumer: boolean test(T)

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Function: void accept(T)

Question 2

Match each Java 17 feature to its description.

Accepted Answer

Sealed Classes: A feature that allows a class or interface to restrict which other classes or interfaces may extend or implement it.. These are key features introduced or enhanced in recent Java versions including 17.

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Enhanced NullPointerExceptions: A feature that allows a class to restrict which subclasses can implement it.

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Switch Expressions: A preview feature that allows testing an expression against a pattern using switch.

Question 3

Match each exception class to its category (checked/unchecked).

Accepted Answer

IOException: Checked. Checked exceptions must be handled or declared; unchecked extend RuntimeException.

Answer

ArrayIndexOutOfBoundsException: Checked

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IllegalArgumentException: Checked

Question 4

Match each annotation to its retention policy.

Accepted Answer

@Override: SOURCE. Retention policies determine how long annotations are retained: SOURCE (discarded by compiler), CLASS (retained in class file but not at runtime), RUNTIME (retained at runtime via reflection). @Override and @SuppressWarnings are SOURCE because they are only used by the compiler. @Deprecated and @FunctionalInterface are RUNTIME because they are accessed via reflection.

Answer

@Override: RUNTIME

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@Deprecated: SOURCE

Question 5

Match each JDBC type to its corresponding Java type.

Accepted Answer

VARCHAR: String. JDBC provides standard mappings from SQL types to Java types: VARCHAR to String, INTEGER to int, DATE to java.sql.Date, BLOB to java.sql.Blob, and CLOB to java.sql.Clob. Common confusions arise from mixing these mappings.

Answer

VARCHAR: java.sql.Date

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INTEGER: String

Question 6

Match each concurrency utility to its purpose.

Accepted Answer

CountDownLatch: A synchronization aid that allows one or more threads to wait until a set of operations being performed in other threads completes.. This question tests understanding of common concurrency utilities in java.util.concurrent such as CountDownLatch, CyclicBarrier, Semaphore, and Exchanger. A common mistake is confusing CountDownLatch (one-time use) with CyclicBarrier (reusable) and mixing up Semaphore's permit-based control with barrier synchronization.

Answer

CyclicBarrier: A synchronization aid that allows one or more threads to wait until a set of operations completes.

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Semaphore: A synchronization aid that allows a set of threads to all wait for each other to reach a common barrier point.

Question 7

Match each Java module directive to its description.

Accepted Answer

requires: Specifies a dependency on another module.. Correct matches: requires specifies dependencies, exports grants compile-time access, opens enables reflective access, provides declares service implementations. Common confusion is between exports and opens due to their related but distinct roles.

Answer

exports: Allows reflective access to a package.

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opens: Makes a package accessible to other modules.

Question 8

Match each I/O stream class to its description.

Accepted Answer

FileInputStream: Reads bytes from a file. The correct matches are based on the direction (read vs write) and type (byte vs character) of the stream. FileInputStream reads bytes; FileOutputStream writes bytes. BufferedReader reads characters with buffering; BufferedWriter writes characters with buffering.

Answer

FileInputStream: Writes bytes to a file

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BufferedReader: Writes text to a character-output stream

Question 9

Match each Java collection class to its underlying data structure.

Accepted Answer

ArrayList: Resizable array. ArrayList uses a resizable array; LinkedList uses a doubly linked list; HashSet uses a hash table; TreeSet uses a red-black tree. Common confusions involve mixing up TreeMap with ArrayList or HashMap with TreeMap.

Answer

HashMap: Red-black tree

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TreeMap: Resizable array

Question 10

Match each Java keyword to its primary purpose.

Accepted Answer

volatile: Ensures that a variable's value is always read from main memory, preventing thread caching.. The correct matches are volatile for visibility, transient for serialization exclusion, and synchronized for locking. Common mistakes include confusing volatile with transient and transient with thread safety.

Answer

volatile: Prevents a field from being serialized.

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transient: Ensures thread safety for a variable.