Oracle Java SE 21 Developer Professional 認定 1z1-830 試験問題:

1. Given:
java
DoubleStream doubleStream = DoubleStream.of(3.3, 4, 5.25, 6.66);
Predicate<Double> doublePredicate = d -> d < 5;
System.out.println(doubleStream.anyMatch(doublePredicate));
What is printed?

A) true
B) 3.3
C) An exception is thrown at runtime
D) false
E) Compilation fails

2. Given:
java
var frenchCities = new TreeSet<String>();
frenchCities.add("Paris");
frenchCities.add("Marseille");
frenchCities.add("Lyon");
frenchCities.add("Lille");
frenchCities.add("Toulouse");
System.out.println(frenchCities.headSet("Marseille"));
What will be printed?

A) [Lille, Lyon]
B) [Paris]
C) [Paris, Toulouse]
D) [Lyon, Lille, Toulouse]
E) Compilation fails

3. Which two of the following aren't the correct ways to create a Stream?

A) Stream<String> stream = Stream.builder().add("a").build();
B) Stream stream = Stream.generate(() -> "a");
C) Stream stream = new Stream();
D) Stream stream = Stream.empty();
E) Stream stream = Stream.of();
F) Stream stream = Stream.ofNullable("a");
G) Stream stream = Stream.of("a");

4. Given a properties file on the classpath named Person.properties with the content:
ini
name=James
And:
java
public class Person extends ListResourceBundle {
protected Object[][] getContents() {
return new Object[][]{
{"name", "Jeanne"}
};
}
}
And:
java
public class Test {
public static void main(String[] args) {
ResourceBundle bundle = ResourceBundle.getBundle("Person");
String name = bundle.getString("name");
System.out.println(name);
}
}
What is the given program's output?

A) JamesJeanne
B) James
C) Jeanne
D) JeanneJames
E) MissingResourceException
F) Compilation fails

5. What do the following print?
java
public class Main {
int instanceVar = staticVar;
static int staticVar = 666;
public static void main(String args[]) {
System.out.printf("%d %d", new Main().instanceVar, staticVar);
}
static {
staticVar = 42;
}
}

A) 666 42
B) 42 42
C) 666 666
D) Compilation fails

質問と回答：