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? Lambda expressions don't return values Curly brackets are required whenever the return keyword is used in a lambda expression A return keyword is always optional in a lambda expression A return keyword is always required in a lambda expression 2 / 56 2. Which of the following are valid ChronoUnit values for LocalTime? NANOS Both B & D YEAR HALF_DAYS DAY 3 / 56 3. What will be the output of the following code?String str = "Hello";str.concat(" World");System.out.println(str); Compilation Error Hello World Hello World 4 / 56 4. How can synchronization be achieved in Java threads? Using the final keyword. Using the static keyword. Using the volatile keyword. Using the synchronized keyword. 5 / 56 5. Select all the classes that extend the String class StringBuffer None StringBuilder StringWriter 6 / 56 6. Which method is used to start a thread in Java? execute() run() start() init() 7 / 56 7. 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 }} null NullPointerException NullPointerException NullPointerException null null None 8 / 56 8. Which method is used to transform each element of a Stream using a provided function? map reduce filter flatMap 9 / 56 9. What is the purpose of the join() method in Java threads? To interrupt the execution of a thread. To notify a thread to stop execution. To schedule the execution of a thread. To wait for a thread to finish its execution. 10 / 56 10. What type of operation is Stream.filter? Mutable Intermediate Source Terminal 11 / 56 11. What is the main advantage of multithreading in Java? Simplified program structure. Reduced memory usage. Improved program performance. Elimination of runtime errors. 12 / 56 12. Which of the following is a checked exception? ArithmeticException IOException ArrayIndexOutOfBoundsException NullPointerException 13 / 56 13. 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 14 / 56 14. Which of the following type of JDBC driver, uses database native protocol? Native-protocol, pure Java driver Native-API, partly Java driver JDBC-ODBC Bridge plus ODBC driver JDBC-Net, pure Java driver 15 / 56 15. Which method is used to compare two strings, ignoring case considerations? compareToIgnoreCase() compareTo() equals() equalsIgnoreCase() 16 / 56 16. Which method is used to transform each element of a Stream using a provided function? flatMap reduce filter map 17 / 56 17. 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); }} 115110 27 11511 1105110 18 / 56 18. Which of the following are valid ChronoField values for LocalDate? DAY_OF_MONTH HOUR_OF_DAY MILLI_OF_SECOND DAY_OF_WEEK Both A & C 19 / 56 19. What is the result of applying the Stream.reduce operation? A list of elements that were reduced An Optional describing the reduced value, if any A boolean indicating if any stream elements match a given predicate A new stream with elements reduced according to a provided accumulator function 20 / 56 20. 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? September F Sept Friday 21 / 56 21. 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 22 / 56 22. Which of these collectors is used for grouping elements of a Stream? Collectors.joining() Collectors.toSet() Collectors.groupingBy() Collectors.toList() 23 / 56 23. Which method is used to start the execution of a thread? begin() start() run() execute() 24 / 56 24. Which of the following is correct about PreparedStatement? 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. None of the above. 25 / 56 25. Which of the following statements correctly describes the behavior of this program? This program will throw a NullPointerException. This program will print 10 in the console. This program will print null in the console. This program will result in a compiler error. 26 / 56 26. Which of the following is correct about Statement class of JDBC? 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. none of the above. 27 / 56 27. Which of the following state(s) is/are NOT legitimate thread state(s)? (Select all that apply.) RUNNABLE TERMINATED EXECUTING WAITING NEW 28 / 56 28. 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 // 2 1.0 Compilation fails on the line marked as // 1 An exception occurs at runtime 29 / 56 29. Which one of the following options correctly describes the behavior of this program? When executed, the program prints the following: “Worker Master ”. The program does not compile and fails with multiple compiler errors. When executed, the program prints “Worker ”, and after that the program hangs (i.e., does not terminate). When executed, the program throws an IllegalMonitorStateException. When executed, the program prints “Worker ” and then terminates. 30 / 56 30. Which of the following is a valid lambda expression? x -> x*x (x, y) -> return x + y; All of the above (int x, int y) -> x + y 31 / 56 31. What does the Stream.peek method do? Filters elements based on a predicate Reduces the stream to a single summary element Consumes and removes an element from the stream Performs an action on each element of the stream without modifying it 32 / 56 32. In which of the following type of ResultSet, the cursor can only move forward in the result set? ResultSet.TYPE_SCROLL_INSENSITIVE ResultSet.TYPE_SCROLL_SENSITIVE ResultSet.TYPE_FORWARD_ONLY None of the above. 33 / 56 33. 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(); }} Thread-0 main Thread-1 Thread-0 Thread-1 Thread-2 main main Thread-0 main Thread-0 Thread-1 34 / 56 34. Lambda expressions can be used with the Java Collections API primarily in ... Iterating All of the above Filtering Sorting 35 / 56 35. What is the purpose of the wait() method in Java threads? To terminate a thread. To pause the execution of a thread. To notify other threads to resume execution. To release the lock held by the thread. 36 / 56 36. 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 always print the following: Table Table Tennis Tennis. This program will throw an IllegalStateException. The output of this program cannot be predicted; it depends on thread scheduling. This program will always print the following: Tennis Tennis Table Table. 37 / 56 37. What is the default priority of a thread in Java? 0 5 10 1 38 / 56 38. 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); }} An exception occurs at runtime Compilation fails on the line marked as // 1 Compilation fails on the line marked as // 2 [20, 20] 39 / 56 39. What is the purpose of the Stream.flatMap method? To filter elements based on a flat structure To map each element to a new value To merge multiple streams into one To replace each element with a stream and then flatten the streams into a single stream 40 / 56 40. You cannot use ... inside lambda expressions. this keyword arithmetic operations return statement break and continue 41 / 56 41. 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 results in a compiler error at statement #1. The program prints: In the run method; the thread name is: thread-0 In the main method; the thread name is: main 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. 42 / 56 42. Which of the following keywords is used to manually throw an exception? catch throw throws try 43 / 56 43. 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 not 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 equal s1 and s3 equal 44 / 56 44. 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)); }} true false Compile-time error ClassCastException at runtime 45 / 56 45. GivenList list = new ArrayList(); // 1list.add(new Integer(2)); // 2list.add(new Object()); // 3Which line will generate a compile-time error? Line marked as // 1 Line marked as // 2 Line marked as // 3 No compile-time error is generated 46 / 56 46. Which of these is a terminal operation in the Stream API? flatMap map forEach filter 47 / 56 47. 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 result in a compilation error at statement #1. 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 #2. The program will compile with no errors and will print “Running” in the console. 48 / 56 48. Which of the following methods can be used to make a thread pause execution for a specific amount of time? pause() yield() sleep() wait() 49 / 56 49. What is the output of the following code?int[] arr = {1, 2, 3, 4, 5};System.out.println(arr[2]); 4 3 1 2 50 / 56 50. 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 prints the following: null string. This program results in a compiler error in statement #2. This program results in a compiler error in statement #1. 51 / 56 51. Which of the following correctly declares an array of integers in Java? int arr[]; int[] arr; int arr = new int[10]; All of the above 52 / 56 52. What is the maximum number of threads that can be created in a Java program? It depends on the amount of available memory. It depends on the number of CPU cores. It is limited to 100 threads. There is no fixed limit. 53 / 56 53. Which of the following is correct about setFetchSize(int)? None of the above. 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. Both of the above. 54 / 56 54. 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 constructor oops in start oops in run oops in start oops in run oops in constructor oops in start oops in constructor oops in run oops in start oops in constructor oops 55 / 56 55. What does the following lambda expression represent?() -> {} A lambda that does nothing and returns void A lambda that accepts two parameters and does nothing A lambda that throws an exception None of the above 56 / 56 56. Which one of the following classes is best suited for storing timestamp values of application events in a file? java.time.Period class java.time.ZoneId class java.time.Duration class java.time.ZoneOffset class java.time.Instant class Your score is 0%
