Implement localization using locales and resource bundles. Parse and format messages, dates, times, and numbers, including currency and percentage values.
1. The correct answer is C.
Explanation:
true
true
true
French (Canada)
French (Canada)
French (Canada)
locale2
.false
true
false
French (Canada)
French (Canada, UNIX2024)
French (Canada)
Locale.CANADA_FRENCH
.false
true
false
French (Canada)
French (Canada, UNIX2024)
Canadian French
This option is correct. Let’s break it down:
locale1.equals(locale2)
is false
because locale2
has a variant ("UNIX2024"
) while locale1
doesn’t.locale1.equals(locale3)
is true
because Locale.CANADA_FRENCH
is equivalent to new Locale("fr", "CA")
.locale2.equals(locale3)
is false
because locale2
has a variant while locale3
doesn’t.locale1.getDisplayName(Locale.ENGLISH)
returns "French (Canada)"
.locale2.getDisplayName(Locale.ENGLISH)
returns "French (Canada, UNIX2024)"
, including the variant.locale3.getDisplayName(Locale.ENGLISH)
returns "Canadian French"
, which is the special display name for this constant.false
false
false
French (Canada)
French (Canada, UNIX2024)
Canadian French
locale1
and locale3
are not equal, which they are.IllegalArgumentException
because UNIX2024
is not a valid variant.
UNIX2024
is not a standard ISO 639 variant code, the Locale
constructor accepts any string as a variant without throwing an exception.2. The correct answer is D.
Explanation:
Locale.Category
enum has three values: DISPLAY
, FORMAT
, and LANGUAGE
.
Locale.Category
enum has only two values: DISPLAY
and FORMAT
. There is no LANGUAGE
category.Locale.setDefault(Locale.Category, Locale)
method can only set the default locale for the FORMAT
category.
Locale.setDefault(Locale.Category, Locale)
method can set the default locale for both the DISPLAY
and FORMAT
categories, not just FORMAT
.Locale.getDefault(Locale.Category)
always returns the same locale regardless of the category specified.
Locale.getDefault(Locale.Category)
can return different locales depending on the category specified. The DISPLAY
and FORMAT
categories can have different default locales.DISPLAY
category affects the language used for displaying user interface elements, while the FORMAT
category affects the formatting of numbers, dates, and currencies.
DISPLAY
category indeed affects the language used for displaying user interface elements (like error messages or GUI labels), while the FORMAT
category affects how numbers, dates, currencies, and other locale-sensitive data are formatted.Locale
methods.
Locale
methods.3. The correct answer is D.
Explanation:
.properties
files.
.properties
files are commonly used for resource bundles, Java also supports class-based resource bundles. These are Java classes that extend ResourceBundle
and provide localized resources programmatically.ResourceBundle.getBundle()
method always throws a MissingResourceException
if the requested bundle is not found.
ResourceBundle.getBundle()
method does not always throw a MissingResourceException
if the requested bundle is not found. It follows a fallback mechanism, trying to find the most specific bundle, then falling back to more general bundles, and finally to the default bundle.fr_FR
(French France) bundle, it will look in the fr
(French) bundle, and then in the default bundle..properties
files are immediately reflected in the running application.
ResourceBundle.getBundle()
is called and then cached. Changes to .properties files are not immediately reflected in a running application. The application usually needs to be restarted or the resource bundle cache cleared for changes to take effect.4. The correct answer is A.
Explanation:
red
blue
config.properties
file.props.clear()
removes all properties from the props
object.System.out.println(props.getProperty("color", "red"))
prints red
because the properties have been cleared, so it uses the default value.System.out.println(props.getProperty("color", "red"))
now prints blue
because it’s loaded from the file.blue
blue
clear()
method call which empties the properties before the first print statement.red
red
FileNotFoundException
.
try-with-resources
block, so it should exist for the second block to read from.null
blue
getProperty()
returns the default value red
when the property is not found, not null
.5. The correct answer is B.
Explanation:
IllegalArgumentException
because the date format is invalid.
"long"
is valid in MessageFormat
and will not throw an exception."Alice"
, the number 3, the word "apples"
, and the price in US currency format.
MessageFormat
will correctly format each parameter according to the specified pattern:{0, date, long}
will format the Date
in long format ("June 1, 2023"
){1}
will simply insert "Alice"
{2,number,integer}
will format 3 as an integer{3}
will insert “apples”{4,number,currency}
will format 19.99 as currency according to the US locale ("$19.99"
){2,number,integer}
format will display 3 as "3.0"
.
{2,number,integer}
format will display 3 as "3"
, not "3.0"
. The integer format doesn’t include decimal places.MessageFormat
doesn’t accept a Locale
in its constructor.
MessageFormat
does have a constructor that accepts a Locale
. The code will compile successfully.{4,number,currency}
format will always display the price in USD, regardless of the Locale
.
MessageFormat
constructor, which in this case is Locale.US
. If a different locale were used, the currency symbol and formatting could change.6. The correct answer is A.
Explanation:
NumberFormat.getCurrencyInstance()
method returns a formatter that can format monetary amounts according to the specified locale’s conventions.
getCurrencyInstance()
method of NumberFormat
returns a currency formatter for the specified locale (or the default locale if none is specified). This formatter applies the appropriate currency symbol, digit grouping, and decimal separator according to the locale’s conventions.NumberFormat
is a concrete class that can be instantiated directly using its constructor.
NumberFormat
is an abstract class and cannot be instantiated directly. Instead, you obtain instances through its static factory methods like getInstance()
, getCurrencyInstance()
, or getPercentInstance()
.setMaximumFractionDigits()
method in NumberFormat
can only accept values between 0 and 3.
setMaximumFractionDigits()
method is not limited to the range of 0 to 3.NumberFormat
always throws a ParseException
if the input doesn’t exactly match the expected format.
NumberFormat
is generally lenient when parsing. It will attempt to parse as much of the string as it can recognize as a number, and will only throw a ParseException
if it can’t parse any part of the string as a number.NumberFormat
class can only format and parse integer values, not floating-point numbers.
NumberFormat
can format and parse both integer and floating-point numbers. It provides methods like setMaximumFractionDigits()
and setMinimumFractionDigits()
specifically for handling decimal places in floating-point numbers.7. The correct answer is A.
Explanation:
2023-06-15 10:30 EDT America/New_York
2023-06-15 23:30 JST Asia/Tokyo
"yyyy-MM-dd HH:mm"
formats the date and time"z"
outputs the short name of the zone, like EDT or JST"VV"
outputs the full time zone ID, like America/New_York
or Asia/Tokyo
The second line shows the correct time in Tokyo, which is 13 hours ahead of New York.2023-06-15 10:30 EDT New_York
2023-06-15 23:30 JST Tokyo
"VV"
pattern outputs the full time zone ID, not just the city name.2023-06-15 10:30 -04:00 America/New_York
2023-06-15 23:30 +09:00 Asia/Tokyo
"z"
pattern outputs the short name of the zone (EDT, JST), not the offset.2023-06-15 10:30 America/New_York
2023-06-15 23:30 Asia/Tokyo
"z"
pattern should output.DateTimeException
because the formatter pattern is invalid.
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