1Z0-829 Handling Date, Time, Text, Numeric and Boolean Values Practice Test 2 — 15 Questions

Question 1

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.

Answer

transient: Ensures thread safety for a variable.

Question 2

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

Answer

@Deprecated: SOURCE

Question 3

A developer needs to parse a date string '2024-07-04' into a LocalDate object. Which approach is correct?

Accepted Answer

LocalDate.parse("2024-07-04"). `LocalDate.parse("2024-07-04")` uses the default ISO-8601 format (yyyy-MM-dd), which matches the given string exactly. The `LocalDate` class provides a static `parse` method that returns a `LocalDate` object without needing an explicit formatter when the input follows the standard pattern.

Answer

LocalDate.of(2024, 07, 04)

Answer

DateFormat.getDateInstance().parse("2024-07-04")

Answer

new LocalDate(2024, 7, 4)

Question 4

Which method checks if a String is empty or contains only whitespace?

Accepted Answer

isBlank(). The `isBlank()` method, introduced in Java 11, returns `true` if the string is empty or contains only whitespace characters (as defined by `Character.isWhitespace()`). This makes it the correct and most direct way to check for blank strings, unlike older approaches that require combining multiple checks.

Answer

length() == 0

Answer

isEmpty()

Answer

trim().isEmpty()

Question 5

Which of the following correctly creates a text block in Java?

Accepted Answer

"""line1
   line2""". It uses the Java text block syntax, which starts and ends with three double-quote characters (""") and places the content on a new line after the opening delimiter. The text block preserves the line break and indentation, making it ideal for multi-line strings without escape sequences.

Answer

"line1
line2"

Answer

'line1
line2'

Answer

"""line1
line2"""

Question 6

A financial application uses BigDecimal for monetary calculations. Which rounding mode should be used to round to the nearest neighbor, and if both neighbors are equidistant, round to the even neighbor?

Accepted Answer

RoundingMode.HALF_EVEN. RoundingMode.HALF_EVEN rounds to the nearest neighbor, and when both neighbors are equidistant (i.e., the fractional part is exactly 0.5), it rounds to the even neighbor. This is the standard rounding mode for financial calculations to minimize cumulative rounding bias over many operations.

Answer

RoundingMode.HALF_UP

Answer

RoundingMode.HALF_DOWN

Answer

RoundingMode.UNNECESSARY

Question 7

Which of the following correctly formats a LocalDateTime object into a string with pattern 'dd/MM/yyyy HH:mm:ss'?

Accepted Answer

DateTimeFormatter.ofPattern("dd/MM/yyyy HH:mm:ss").format(dateTime). `DateTimeFormatter.ofPattern("dd/MM/yyyy HH:mm:ss")` creates a formatter with the specified pattern, and calling `.format(dateTime)` on that formatter converts a `LocalDateTime` object to a string in the exact requested format. This is the standard approach in Java 8+ using the `java.time` API, which is thread-safe and immutable.

Answer

String.format("%1$td/%1$tm/%1$tY %1$tH:%1$tM:%1$tS", dateTime)

Answer

new SimpleDateFormat("dd/MM/yyyy HH:mm:ss").format(dateTime)

Answer

dateTime.format(DateTimeFormatter.ISO_LOCAL_DATE_TIME)

Question 8

A program reads user input as a string and needs to parse it into an integer, handling invalid input gracefully. Which code snippet correctly uses try-catch to parse and prints the result or 'Invalid number'?

Accepted Answer

try { int num = Integer.parseInt(input); System.out.println(num); } catch (NumberFormatException e) { System.out.println("Invalid number"); }. It uses `Integer.parseInt(input)` which throws a `NumberFormatException` for invalid input, and the catch block specifically catches that exception to print 'Invalid number'. This is the standard, idiomatic Java approach for parsing integers with error handling, as it directly addresses the requirement without unnecessary overhead or false positives.

Answer

try { int num = Integer.valueOf(input).intValue(); System.out.println(num); } catch (Exception e) { System.out.println("Invalid number"); }

Answer

int num = Integer.parseInt(input); System.out.println(num);

Answer

if (input.matches("\d+")) { int num = Integer.parseInt(input); System.out.println(num); } else { System.out.println("Invalid number"); }

Question 9

Given: ZonedDateTime zdt = ZonedDateTime.of(2024, 3, 10, 2, 30, 0, 0, ZoneId.of("America/New_York")); In the US, on March 10, 2024, clocks spring forward at 2:00 AM to 3:00 AM. What is the output of System.out.println(zdt);?

Accepted Answer

2024-03-10T03:30-04:00[America/New_York]. When a ZonedDateTime is created for a time that falls within a DST gap (2:00 AM to 3:00 AM on March 10, 2024, in America/New_York), the Java API automatically adjusts the time forward to the next valid offset. The local time 2:30 AM does not exist because clocks spring forward to 3:00 AM, so the ZonedDateTime is normalized to 3:30 AM with the DST offset -04:00. This behavior is defined by the ZonedDateTime.of method, which resolves invalid local times by shifting to the offset after the gap.

Answer

Throws DateTimeException

Answer

2024-03-10T02:30-05:00[America/New_York]

Answer

2024-03-10T02:30-04:00[America/New_York]

Question 10

Which code correctly reads a line of text from the console using System.console()?

Accepted Answer

Console cons = System.console(); String line = cons.readLine();. `System.console()` returns a `Console` object that provides a direct, secure method for reading text from the console without buffering issues. The `readLine()` method reads a line of text as a `String`, which is the intended approach when using the console API.

Answer

Scanner sc = new Scanner(System.in); String line = sc.nextLine();

Answer

DataInputStream dis = new DataInputStream(System.in); String line = dis.readLine();

Answer

BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); String line = br.readLine();

Question 11

What is the result of executing the following code snippet?

BigDecimal d1 = new BigDecimal("1.00");
BigDecimal d2 = new BigDecimal("1.0");
System.out.println(d1.equals(d2));

Accepted Answer

false. The `equals` method of `BigDecimal` compares both the numeric value and the scale (number of digits after the decimal point). Since `new BigDecimal("1.00")` has a scale of 2 and `new BigDecimal("1.0")` has a scale of 1, they are not considered equal by `equals`, even though they represent the same mathematical value. Therefore, the output is `false`.

Answer

compile error

Answer

true

Answer

1

Question 12

Which three of the following are valid methods in the String class in Java 17? (Choose three.)

Accepted Answer

translateEscapes(). `translateEscapes()` is a valid instance method introduced in Java 14 (and present in Java 17) that translates escape sequences (e.g., `
` to newline) in a string. Option C is correct because `toLowerCase(Locale)` is a standard overloaded method in the String class that converts all characters to lowercase using the specified locale. Option D is correct because `transform(Function<String, String>)` is a valid method added in Java 12 that applies the given function to the string and returns the result.

Answer

substring(int, int, Locale)

Answer

indent(String)

Question 13

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 14

Which two of the following are valid ways to create a LocalDate representing the current date in the system's default timezone? (Choose two.)

Accepted Answer

LocalDate.now(). `LocalDate.now()` is the standard, straightforward method to obtain the current date in the system's default timezone, as defined in the Java Time API (JSR-310). It internally uses the system clock and the default timezone to return a `LocalDate` instance without requiring any additional parameters.

Answer

LocalDate.from(Instant.now())

Answer

new LocalDate()

Answer

LocalDate.ofEpochDay(System.currentTimeMillis() / (24*60*60*1000))

Question 15

Refer to the exhibit. What is the output?

Accepted Answer

true. The code uses `Boolean.valueOf(true)` which returns the `Boolean` constant `Boolean.TRUE`, and `Boolean.TRUE` is a singleton object that is `==` to itself. The `==` operator compares object references, not values, so the comparison `Boolean.valueOf(true) == Boolean.TRUE` evaluates to `true` because both refer to the same cached `Boolean` instance from the `Boolean` class's static final fields.

Answer

compile error

Answer

null

Answer

false