Oracle 1Z0-830 Certification Sample Questions and Answers

1Z0-830 PDF, 1Z0-830 Dumps PDF Free Download, 1Z0-830 Latest Dumps Free PDF, Java SE Developer Professional PDF DumpsThe Oracle Java SE Developer Professional (1Z0-830) Sample Question Set is designed to help you prepare for the Oracle Certified Professional Java SE 21 Developer certification exam. To become familiar with the actual Oracle Certification exam environment, we suggest you try our Sample Oracle 1Z0-830 Certification Practice Exam.

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Oracle 1Z0-830 Sample Questions:

01. What is the result of executing the following code?
4: var p = Path.of("sloth.schedule");
5: var a = Files.readAttributes(p, BasicFileAttributes.class);
6: Files.mkdir(p.resolve(".backup"));
7: if(a.size()>0 && a.isDirectory()) {
8:    a.setTimes(null,null,null);
9: }
(Choose two.)
a) It compiles and runs without issue.
b) The code will not compile because of line 5.
c) The code will not compile because of line 6.
d) The code will not compile because of line 7.
e) The code will not compile because of line 8.
f) The code will not compile because of line 4.
 
02. Which tool can be used to create a runtime image for a Java application?
a) jlink
b) javac
c) jar
d) jmod
 
03. A class implements an interface but does not provide implementations for all of the interface’s abstract methods.
What must be true for the class to compile?
a) Compilation error
b) The class must be declared abstract
c) The class must implement all methods at runtime
d) The interface methods will be ignored
 
04. Given the following code snippet, which options correctly create a parallel stream?
var c = List.of(19, 66);
var s = ThreadLocalRandom.current().doubles();
var p = ________________;
(Choose two.)
a) new ParallelStream(s)
b) c.parallel()
c) s.parallelStream()
d) c.parallelStream()
e) new ParallelStream(c)
f) s.parallel()
 
05. What is the output of the following code?
public class Demo {
public static void main(String[] args) throws Exception {
var res = new java.io.StringReader("hi");
try (res) {
System.out.print("read ");
}
System.out.print("done");
}
}
a) Compilation fails because the resource variable is declared using var.
b) Compilation fails because a resource must be declared inside the resource specification.
c) read done, and the reader is closed only when the method returns.
d) read done
 
06. Consider the following code.
public class Demo {
public static void main(String[] args) {
try {
Object o = null;
o.toString();
} catch (RuntimeException e) {
System.out.print("runtime");
} catch (NullPointerException e) {
System.out.print("npe");
}
}
}
What is the result?
a) Compilation fails because the second catch block is unreachable.
b) The code compiles and prints runtime.
c) The code compiles and prints runtimenpe.
d) The code compiles and prints npe.
 
07. Which loop declares its initialization outside the loop and evaluates its condition before the first iteration?
a) for-each loop
b) for loop
c) while loop
d) do-while loop
 
08. Two modules on the module path each contain a package named com.shared.util, and a third module requires both.
What is the result?
a) The module graph fails to resolve because a package may be defined in only one module.
b) The packages are merged, and the reading module sees the union of their public types.
c) The module declared first on the module path wins, and the other package is ignored.
d) Both packages are visible, and any ambiguous type must be referenced by its fully qualified name.
 
09. Which two statements are true about sealed types in Java SE 21?
(Choose two.)
a) A switch over a sealed type needs no default branch if every permitted subtype is covered.
b) Every direct subclass of a sealed class must be declared final, sealed, or non-sealed.
c) A permits clause may be omitted only when the permitted subtypes are in a different package.
d) Sealing a type prevents it from being used as the selector of a switch expression.
e) A sealed interface cannot be implemented by a record.
f) A sealed class may be extended by any class in the same package without being permitted.
 
10. Suppose you have separate modules for a service provider interface, service provider, service locator, and consumer.
If you add a second service provider module, how many of the existing modules do you need to recompile?
a) Two
b) One
c) Zero
d) Three
e) Four

Answers:

Question: 01

Answer: c, e

Question: 02

Answer: a

Question: 03

Answer: b

Question: 04

Answer: d, f

Question: 05

Answer: d

Question: 06

Answer: a

Question: 07

Answer: c

Question: 08

Answer: a

Question: 09

Answer: a, b

Question: 10

Answer: c

 

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