Free Oracle 1Z0-829 Practice Questions

Question 1

Which statement is true?

1. IllegalStateException is thrown if a thread in waiting state is moved back to runnable.
2. A thread in waiting state consumes CPU cycles.
3. After the timed wait expires, the waited thread moves to the terminated state.
4. A thread in waiting state must handle InterruptedException.

Question 2

Given the code fragment: List<Integer> listOfNumbers = List.of(1, 2, 3, 4, 5, 6, 7, 8, 9, 10); Which code fragment returns different values?

1. int sum = listOfNumbers.stream().reduce(0, Integer::sum) + 5;
2. int sum = listOfNumbers.parallelStream().reduce(0, Integer::sum) + 5 ;
3. int sum = listOfNumbers.parallelStream().reduce((m, n) -> m + n).orElse(5) + 5;
4. int sum = listOfNumbers.parallelStream().reduce(5, Integer::sum);
5. int sum = listOfNumbers.stream().reduce(5, (a, b) -> a+ b);

Question 3

Which statement is true about modules?

1. Only unnamed modules are on the module path.
2. Automatic and named modules are on the module path.
3. Only automatic modules are on the module path.
4. Only named modules are on the module path.
5. Automatic and unnamed modules are on the module path.

Question 4

Which statement is true?

1. The --add-exports option is always recommended in a Java command.
2. The --add-exports option is not allowed in a Java command.
3. The --add-requires option is not allowed in a Java command.
4. The --add-requires option is allowed but not recommended in a Java command.

Question 5

Assume you have an automatic module from the module path display-ascii-0.2.jar. Which name is given to the automatic module based on the given JAR file?

1. display-ascii-0
2. display-ascii
3. display.ascii
4. display-ascii-0.2

Question 6

Given:

import java.io.Serializable;
public class Software implements Serializable {
    private String title;
    public Software(String title) {
        this.title = title;
        System.out.print("Software ");
    }
    public String toString() { return title; }
}

public class Game extends Software {
    private int players;
    public Game(String title, int players) {
        super(title);
        this.players = players;
        System.out.print("Game ");
    }
    public String toString() { return super.toString() + " " + players; }
}

import java.io.*;
public class AppStore {
    public static void main(String[] args) {
        Software s = new Game("Chess", 2);
        try (ObjectOutputStream out =
                new ObjectOutputStream(new FileOutputStream("game.ser"))) {
            out.writeObject(s);
        } catch (Exception e) {
            System.out.println("write error");
        }
        try (ObjectInputStream in =
                new ObjectInputStream(new FileInputStream("game.ser"))) {
            s = (Software) in.readObject();
        } catch (Exception e) {
            System.out.println("read error");
        }
        System.out.println(s);
    }
}

What is the result?

1. Software Game read error
2. Software Game Chess 0
3. Software Game Software Game Chess 2
4. Software Game Chess 2
5. Software Game write error
6. Software Game Software Game Chess 0

Question 7

Which two statements are true about modules in the Java Platform Module System? (Choose two.)

1. The module-info.java has to be located in the Java bin directory.
2. They are a group of related Java packages and resources such as XML files, images, and properties file.
3. The classes in a module are loaded using class-path.
4. They support versioning of Java modules.
5. Packages within the module are hidden by default.

Question 8

Assuming that the data.txt file exists and has the following content:

text1
text2
text3

Given the code fragment:

try {
    Path p = new File("data.txt").toPath();
    Stream<String> lines = Files.lines(p);
    String data = lines.collect(Collectors.joining("-"));
    System.out.println(data);
    String data2 = Files.readAllLines(p).get(3);
    System.out.println(data2);
} catch (IOException ex) {
    System.out.println(ex);
}

What is the result?

1. text1text2text3text3
2. text1-text2-text3 A java.lang.IndexOutOfBoundsException is thrown.
3. text1-text2-text3 text1 text2 text3
4. text1-text2-text3 text3

Question 9

Given the code fragment:

ExecutorService executorService = Executors.newSingleThreadExecutor();
Set<Callable<String>> workers = new HashSet<Callable<String>>();
workers.add(new Callable<String>() {
    public String call() throws Exception {
        return "1";
    }
});
workers.add(new Callable<String>() {
    public String call() throws Exception {
        return "2";
    }
});
workers.add(new Callable<String>() {
    public String call() throws Exception {
        return "3";
    }
});

Which code fragment invokes all callable objects in the workers set?

1. for (int i=0; i<3;i++) { String result = executorService.invokeAny(cThreads); System.out.println(result); }
2. executorService.submit(cThreads);
3. List<Future<String>> futures = executorService.invokeAny(workers); for (Future<String> future : futures) { System.out.println(future.get()); }
4. List<Future<String>> futures = executorService.invokeAll(workers); for (Future<String> future : futures) { System.out.println(future.get()); }

Question 10

Which statement is true?

1. The lock() method returns a boolean indicator immediately regardless if it has or has not managed to acquire the lock.
2. The lock() method returns a boolean indicator immediately if it has managed to acquire the lock, otherwise it waits for the lock acquisition.
3. The tryLock() method returns a boolean indicator immediately if it has managed to acquire the lock, otherwise it waits for the lock acquisition.
4. The tryLock() method returns a boolean indicator immediately regardless if it has or has not managed to acquire the lock.

Question 11

Which statement is true about migration?

1. Every module is moved to the module path in a bottom-up migration.
2. Every module is moved to the module path in a top-down migration.
3. Unnamed modules are automatic modules in a top-down migration.
4. The required modules migrate before the modules that depend on them in a top-down migration.