Oracle 1z0-830 Exam With Confidence Using Practice Dumps

Why does the compilation fail?

TheJava switch statement does not support primitive type pattern matchingin switch expressions as of Java 21.

The case pattern case int i -> "integer"; isinvalidbecausepattern matching with primitive types (like int or long) is not yet supported in switch statements.

The error occurs at case int i -> "integer";, leading to acompilation failure.

Correcting the Code

Since myVar is of type Object,autoboxing converts 0 into an Integer.

To make the code compile, we should use Integer instead of int:

java

Object myVar = 0;

String print = switch (myVar) {

case Integer i -> "integer";

case Long l -> "long";

case String s -> "string";

default -> "";

};

System.out.println(print);

Output:

bash

integer

Thus, the correct answer is:Compilation fails.

References:

Java SE 21 - Pattern Matching for switch

Java SE 21 - switch Expressions

In Java's java.nio.file package, the Path class represents a file path in a file system. The Paths.get(String first, String... more) method is used to create a Path instance by converting a path string or URI.

In the provided code snippet, the Path object path is created with the string "C:\\home\\joe\\foo". This represents an absolute path on a Windows system.

The getName(int index) method of the Path class returns a name element of the path as a Path object. The index is zero-based, where index 0 corresponds to the first element in the path's name sequence. It's important to note that the root component (e.g., "C:\" on Windows) is not considered a name element and is not included in this sequence.

Therefore, for the path "C:\\home\\joe\\foo":

Root Component:"C:\"

Name Elements:

Index 0: "home"

Index 1: "joe"

Index 2: "foo"

When path.getName(0) is called, it returns the first name element, which is "home". Thus, the output of the System.out.println statement is home.

The CopyOnWriteArrayList is a thread-safe variant of ArrayList in which all mutative operations (such as add, set, and remove) are implemented by creating a fresh copy of the underlying array. This design allows for safe iteration over the list without requiring external synchronization, as iterators operate over a snapshot of the array at the time the iterator was created. Consequently, modifications made to the list after the creation of an iterator are not reflected in that iterator.

docs.oracle.com

Evaluation of Options:

Option A:Correct. This statement accurately describes the behavior of CopyOnWriteArrayList.

Option B:Incorrect. CopyOnWriteArrayList is thread-safe and is designed to prevent interference among concurrent threads.

Option C:Incorrect. Iterators of CopyOnWriteArrayList do not reflect additions, removals, or changes made to the list after the iterator was created; they operate on a snapshot of the list's state at the time of their creation.

Option D:Incorrect. CopyOnWriteArrayList allows null elements.

Option E:Incorrect. Element-changing operations on iterators, such as remove, set, and add, are not supported in CopyOnWriteArrayList and will throw UnsupportedOperationException.