1z1-830無料問題集「Oracle Java SE 21 Developer Professional」

質問 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）An exception is thrown at runtime

（B）Compilation fails

（C）true

（D）3.3

（E）false

正解：B 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 2

Given:
java
String colors = "red\n" +
"green\n" +
"blue\n";
Which text block can replace the above code?

（A）None of the propositions

（B）java
String colors = """
red
green
blue
""";

（C）java
String colors = """
red \s
green\s
blue \s
""";

（D）java
String colors = """
red \
green\
blue \
""";

（E）java
String colors = """
red \t
green\t
blue \t
""";

正解：B 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 3

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）Compilation fails

（C）666 666

（D）42 42

正解：D 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 4

Given:
java
Object input = 42;
String result = switch (input) {
case String s -> "It's a string with value: " + s;
case Double d -> "It's a double with value: " + d;
case Integer i -> "It's an integer with value: " + i;
};
System.out.println(result);
What is printed?

（A）It's an integer with value: 42

（B）It's a string with value: 42

（C）It's a double with value: 42

（D）It throws an exception at runtime.

（E）null

（F）Compilation fails.

正解：F 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 5

Which three of the following are correct about the Java module system?

（A）If a request is made to load a type whose package is not defined in any known module, then the module system will attempt to load it from the classpath.

（B）We must add a module descriptor to make an application developed using a Java version prior to SE9 run on Java 11.

（C）The unnamed module exports all of its packages.

（D）The unnamed module can only access packages defined in the unnamed module.

（E）If a package is defined in both a named module and the unnamed module, then the package in the unnamed module is ignored.

（F）Code in an explicitly named module can access types in the unnamed module.

正解：A、C、E 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 6

Given:
java
var array1 = new String[]{ "foo", "bar", "buz" };
var array2[] = { "foo", "bar", "buz" };
var array3 = new String[3] { "foo", "bar", "buz" };
var array4 = { "foo", "bar", "buz" };
String array5[] = new String[]{ "foo", "bar", "buz" };
Which arrays compile? (Select 2)

（A）array2

（B）array4

（C）array3

（D）array1

（E）array5

正解：D、E 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 7

Given:
java
List<String> frenchAuthors = new ArrayList<>();
frenchAuthors.add("Victor Hugo");
frenchAuthors.add("Gustave Flaubert");
Which compiles?

（A）Map<String, List<String>> authorsMap4 = new HashMap<String, ArrayList<String>>(); java authorsMap4.put("FR", frenchAuthors);

（B）Map<String, ArrayList<String>> authorsMap1 = new HashMap<>();
java
authorsMap1.put("FR", frenchAuthors);

（C）Map<String, List<String>> authorsMap5 = new HashMap<String, List<String>>(); java authorsMap5.put("FR", frenchAuthors);

（D）var authorsMap3 = new HashMap<>();
java
authorsMap3.put("FR", frenchAuthors);

（E）Map<String, ? extends List<String>> authorsMap2 = new HashMap<String, ArrayList<String>> (); java authorsMap2.put("FR", frenchAuthors);

正解：A、C、D 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

質問 8

Given:
java
var deque = new ArrayDeque<>();
deque.add(1);
deque.add(2);
deque.add(3);
deque.add(4);
deque.add(5);
System.out.print(deque.peek() + " ");
System.out.print(deque.poll() + " ");
System.out.print(deque.pop() + " ");
System.out.print(deque.element() + " ");
What is printed?

（A）1 5 5 1

（B）1 1 2 3

（C）1 1 1 1

（D）5 5 2 3

（E）1 1 2 2

正解：B 解答を投票する

解説: (JPNTest メンバーにのみ表示されます)

1z1-830 無料問題集「Oracle Java SE 21 Developer Professional」

弊社を連絡する

関連リンク

トップ試験