Java Quizz Dive into our tech quiz zone and put your technical skills to the test! Our quizzes cover a wide array of technical topics, perfect for sharpening your knowledge and challenging your understanding. Compete with others, see your rankings, and boost your technical proficiency. Start quizzing today! 1 / 56 1. Which of the following statements are true? A return keyword is always required in a lambda expression A return keyword is always optional in a lambda expression Curly brackets are required whenever the return keyword is used in a lambda expression Lambda expressions don't return values 2 / 56 2. Which of the following is correct about setFetchSize(int)? setFetchSize(int) defines the number of rows that will be read from the database when the ResultSet needs more rows. setFetchSize(int) affects how the database returns the ResultSet data. None of the above. Both of the above. 3 / 56 3. Which of the following methods can be used to make a thread pause execution for a specific amount of time? yield() wait() pause() sleep() 4 / 56 4. You cannot use ... inside lambda expressions. this keyword arithmetic operations return statement break and continue 5 / 56 5. In which of the following type of ResultSet, the cursor can only move forward in the result set? ResultSet.TYPE_SCROLL_SENSITIVE None of the above. ResultSet.TYPE_FORWARD_ONLY ResultSet.TYPE_SCROLL_INSENSITIVE 6 / 56 6. Which of the following is a checked exception? ArrayIndexOutOfBoundsException IOException ArithmeticException NullPointerException 7 / 56 7. Which of the following are valid ChronoField values for LocalDate? MILLI_OF_SECOND DAY_OF_MONTH Both A & C HOUR_OF_DAY DAY_OF_WEEK 8 / 56 8. Which method is used to start a thread in Java? run() init() execute() start() 9 / 56 9. What is the output of the following code?int[] arr = {1, 2, 3, 4, 5};System.out.println(arr[2]); 1 3 2 4 10 / 56 10. Which of these collectors is used for grouping elements of a Stream? Collectors.toList() Collectors.joining() Collectors.toSet() Collectors.groupingBy() 11 / 56 11. Which of the following keywords is used to manually throw an exception? throws throw catch try 12 / 56 12. Which of the following is a valid lambda expression? (int x, int y) -> x + y x -> x*x All of the above (x, y) -> return x + y; 13 / 56 13. Lambda expressions can be used with the Java Collections API primarily in ... Iterating Filtering Sorting All of the above 14 / 56 14. What will be the output of the below statements?public class Test { public static void main(String[] args) { String s1 = null; System.out.println(s1); //line 2 System.out.println(s1.toString()); //line 3 }} None null null null NullPointerException NullPointerException NullPointerException 15 / 56 15. What is the main advantage of multithreading in Java? Simplified program structure. Improved program performance. Elimination of runtime errors. Reduced memory usage. 16 / 56 16. Which one of the following classes is best suited for storing timestamp values of application events in a file? java.time.ZoneId class java.time.Period class java.time.Instant class java.time.ZoneOffset class java.time.Duration class 17 / 56 17. Consider this code segment?DateTimeFormatter formatter =DateTimeFormatter.ofPattern("EEEE", Locale.US);System.out.println(formatter.format(LocalDateTime.now()));Which of the following outputs matches the string pattern "EEEE" given in this code segment? Sept Friday September F 18 / 56 18. Which one of the following options correctly describes the behavior of this program? When executed, the program prints “Worker ”, and after that the program hangs (i.e., does not terminate). When executed, the program prints the following: “Worker Master ”. When executed, the program throws an IllegalMonitorStateException. The program does not compile and fails with multiple compiler errors. When executed, the program prints “Worker ” and then terminates. 19 / 56 19. What is the default priority of a thread in Java? 5 10 0 1 20 / 56 20. Consider the following program and predict the output:public class Test { public static void main(String[] args) { String s = new String("5"); System.out.println(1 + 10 + s + 1 + 10); }} 11511 27 115110 1105110 21 / 56 21. What is the output of the following program?public class Question { public static void main(String[] args) { Question q = new Question(); List l = new ArrayList(); l.add(20); l.add(30); q.m1(l); } private void m1(List l) { m2(l); // 1 } private void m2(List l) { l.set(1, l.get(0)); // 2 System.out.println(l); }} [20, 20] Compilation fails on the line marked as // 1 An exception occurs at runtime Compilation fails on the line marked as // 2 22 / 56 22. Which of the following type of JDBC driver, uses database native protocol? JDBC-ODBC Bridge plus ODBC driver JDBC-Net, pure Java driver Native-API, partly Java driver Native-protocol, pure Java driver 23 / 56 23. GivenList list = new ArrayList(); // 1list.add(new Integer(2)); // 2list.add(new Object()); // 3Which line will generate a compile-time error? Line marked as // 2 Line marked as // 1 Line marked as // 3 No compile-time error is generated 24 / 56 24. What is the output of the following program?public class Question { T t; public static void main(String[] args) { Question q = new Question(); // 1 q.t = new Float(1); // 2 System.out.println(q.t); }} Compilation fails on the line marked as // 1 An exception occurs at runtime Compilation fails on the line marked as // 2 1.0 25 / 56 25. Which of the following correctly declares an array of integers in Java? int arr = new int[10]; int arr[]; All of the above int[] arr; 26 / 56 26. What type of operation is Stream.filter? Terminal Intermediate Source Mutable 27 / 56 27. Which of these is a terminal operation in the Stream API? forEach filter flatMap map 28 / 56 28. Consider the following program and predict the output:class MyThread extends Thread { public MyThread(String name) { this.setName(name); start(); System.out.println("in constructor " + getName()); } @Override public void start() { System.out.println("in start " + getName()); } public void run() { System.out.println("in run " + getName()); }}public class ThreadTest { public static void main(String[] args) { new MyThread("oops"); }} in start oops in run oops in constructor oops in constructor oops in start oops in run oops in start oops in constructor oops in run oops in start oops in constructor oops 29 / 56 29. Which of the following is correct about Statement class of JDBC? none of the above. Both of the above. Statement encapsulates an SQL statement which is passed to the database to be parsed and compiled. Statement encapsulates an SQL statement which is passed to the database to be planned and executed. 30 / 56 30. Which method is used to transform each element of a Stream using a provided function? map reduce flatMap filter 31 / 56 31. Consider the following program and choose the right option:class MyThread extends Thread { public void run() { System.out.println("Running"); }}public class ThreadTest { public static void main(String args[]) throws InterruptedException { Runnable r = new MyThread(); // #1 Thread myThread = new Thread(r); // #2 myThread.start(); }} The program will compile with no errors and will print “Running” in the console. The program will compile with no errors but does not print any output in the console. The program will result in a compilation error at statement #1. The program will result in a compilation error at statement #2. 32 / 56 32. Consider the following program and predict its output:public class Test { public static void main(String[] args) { String str = null; switch (str) { // #1 case "null": System.out.println("null string"); // #2 break; } }} This program results in throwing a NullPointerException. This program results in a compiler error in statement #2. This program prints the following: null string. This program results in a compiler error in statement #1. 33 / 56 33. What is the purpose of the wait() method in Java threads? To notify other threads to resume execution. To pause the execution of a thread. To terminate a thread. To release the lock held by the thread. 34 / 56 34. Which method is used to start the execution of a thread? run() start() execute() begin() 35 / 56 35. Which method is used to compare two strings, ignoring case considerations? equalsIgnoreCase() equals() compareToIgnoreCase() compareTo() 36 / 56 36. What is the purpose of the join() method in Java threads? To notify a thread to stop execution. To wait for a thread to finish its execution. To schedule the execution of a thread. To interrupt the execution of a thread. 37 / 56 37. What will be the output of the following code?String str = "Hello";str.concat(" World");System.out.println(str); Hello World World Compilation Error Hello 38 / 56 38. What is the output of the following code?try { int a = 10 / 0;} catch (ArithmeticException e) { System.out.println("Exception caught");} finally { System.out.println("Finally block");} Finally block Exception caught Finally block Exception caught 39 / 56 39. How can synchronization be achieved in Java threads? Using the final keyword. Using the volatile keyword. Using the static keyword. Using the synchronized keyword. 40 / 56 40. What does the Stream.peek method do? Reduces the stream to a single summary element Performs an action on each element of the stream without modifying it Filters elements based on a predicate Consumes and removes an element from the stream 41 / 56 41. Which of the following is correct about PreparedStatement? None of the above. Both of the above. PreparedStatement allows mapping different requests with same prepared statement but different arguments to execute the same execution plan. Prepared statements are more secure because they use bind variables, which can prevent SQL injection attack. 42 / 56 42. Consider the following program:public class StrEqual { public static void main(String[] args) { String s1 = "hello"; String s2 = new String("hello"); String s3 = "hello"; if (s1 == s2) { System.out.println("s1 and s2 equal"); } else { System.out.println("s1 and s2 not equal"); } if (s1 == s3) { System.out.println("s1 and s3 equal"); } else { System.out.println("s1 and s3 not equal"); } }}Which one of the following options provides the output of this program when executed? s1 and s2 equal s1 and s3 equal s1 and s2 not equal s1 and s3 not equal s1 and s2 equal s1 and s3 not equal s1 and s2 not equal s1 and s3 equal 43 / 56 43. Select all the classes that extend the String class None StringBuffer StringBuilder StringWriter 44 / 56 44. Which of the following are valid ChronoUnit values for LocalTime? Both B & D HALF_DAYS DAY YEAR NANOS 45 / 56 45. Which of the following state(s) is/are NOT legitimate thread state(s)? (Select all that apply.) EXECUTING TERMINATED WAITING RUNNABLE NEW 46 / 56 46. What is the result of applying the Stream.reduce operation? A list of elements that were reduced A new stream with elements reduced according to a provided accumulator function An Optional describing the reduced value, if any A boolean indicating if any stream elements match a given predicate 47 / 56 47. Which of the following statements correctly describes the behavior of this program? This program will print null in the console. This program will result in a compiler error. This program will print 10 in the console. This program will throw a NullPointerException. 48 / 56 48. Consider the following program and predict the output:class MyThread implements Runnable { @Override public void run() { System.out.println(Thread.currentThread().getName()); }}public class ThreadTest { public static void main(String arg[]) { Thread thread = new Thread(new MyThread()); thread.run(); thread.run(); thread.start(); }} main Thread-0 Thread-1 Thread-0 Thread-1 Thread-2 Thread-0 main Thread-1 main main Thread-0 49 / 56 49. What is the purpose of the Stream.flatMap method? To map each element to a new value To filter elements based on a flat structure To merge multiple streams into one To replace each element with a stream and then flatten the streams into a single stream 50 / 56 50. Consider the following program and choose the correct answer:class MyThread extends Thread { public MyThread(String name) { this.setName(name); } @Override public void run() { try { sleep(100); } catch (InterruptedException e) { e.printStackTrace(); } play(); } private void play() { System.out.print(getName()); System.out.print(getName()); }}public class ThreadTest { public static void main(String args[]) throws InterruptedException { Thread tableThread = new MyThread("Table"); Thread tennisThread = new MyThread("Tennis"); tableThread.start(); tennisThread.start(); }} This program will throw an IllegalStateException. This program will always print the following: Table Table Tennis Tennis. This program will always print the following: Tennis Tennis Table Table. The output of this program cannot be predicted; it depends on thread scheduling. 51 / 56 51. What does the following lambda expression represent?() -> {} A lambda that accepts two parameters and does nothing A lambda that does nothing and returns void None of the above A lambda that throws an exception 52 / 56 52. Which method is used to transform each element of a Stream using a provided function? map filter flatMap reduce 53 / 56 53. Consider the following program and predict the output:class MyThread extends Thread { @Override public void run() { System.out.println("In run method; thread name is: " + Thread.currentThread().getName()); }}public class ThreadTest { public static void main(String args[]) { Thread myThread = new MyThread(); myThread.run(); // #1 System.out.println("In main method; thread name is: " + Thread.currentThread().getName()); }} The program prints the following: In run method; thread name is: main In main method; thread name is: main The program results in a runtime exception. The program prints: In the run method; the thread name is: thread-0 In the main method; the thread name is: main The program results in a compiler error at statement #1. 54 / 56 54. What is the main purpose of the Stream.sorted method? To sort the elements of the stream in their natural order or by a provided comparator To reverse the order of elements in the stream To randomly shuffle the elements of the stream To remove duplicate elements from the stream 55 / 56 55. What is the maximum number of threads that can be created in a Java program? There is no fixed limit. It depends on the amount of available memory. It depends on the number of CPU cores. It is limited to 100 threads. 56 / 56 56. What will be the output of the below statements?public class Test { public static void main(String[] args) { String s1 = "abc"; StringBuffer s2 = new StringBuffer(s1); System.out.println(s1.equals(s2)); }} Compile-time error true ClassCastException at runtime false Your score is 0%
