Java FPT Software (Fsoft) Academy Practice Test

These questions are part of the practice quiz. Start practicing

• What will happen when you compile and run the following Java code? abstract class Base { abstract void amethod(); static int i; } public class Derived extends Base { public static void main(String[] argv) { int[] ar = new int[5]; for (i = 0; i < ar.length; i++) System.out.print(ar[i]); } }
• Generics basics and an example of a bounded wildcard.
• Which class is used to read characters and strings in Java from the console?
• What is the result of compiling code that declares a raw List and calls sort() without a comparator?
• Which statement about the enum-based singleton pattern is true?
• When repeatedly calling readLine() on a BufferedReader until no more data remains, what is returned at end of stream?
• Which statement about CopyOnWriteArrayList is true?
• Which type of dependency injection in Spring provides dependencies via the class constructor?
• Which approach is commonly used to propagate checked exceptions from a stream operation without altering method signatures?
• Evaluate the following do-while loop behavior: do{ if(count % 3 == 0) continue; sum += count; } while(count++ < 11); System.out.println(sum); If sum starts at 0 and count starts at 0, what is printed?
• If you store the result of d.substring(1,7) into a new variable t while d is 'bookkeeper', what is t?
• What do wait(), notify(), and notifyAll() do in Java concurrency?
• Which tool is used to compile Java code?
• Which statement best differentiates method overloading from method overriding?
• Which statement best describes what happens when you compile and run the following code? class Triangle { public int base; public int height; private final double ANGLE; public void setAngle(double a) { ANGLE = a; } public static void main(String[] args) { Triangle t = new Triangle(); t.setAngle(90); } }
• Which expression creates a String at compile time due to constant folding?
• Which statement demonstrates a concise way to create a comparator that sorts by name using Java 8 features?
• In Java, if a method receives an int parameter and prints the parameter value after applying the pre-increment operator (++), what value is printed first?
• Which statement prints to the standard output in Java?
• In Java, when a subclass is instantiated, in what order are the constructors invoked?
• Which singleton pattern approach provides thread-safety with lazy initialization using the Initialization-on-demand Holder idiom?
• If a list l contains at least two elements, what does l.subList(1, 1) return?
• Which annotation meta-annotation controls whether an annotation is retained at runtime?
• Which statement initializes a list with two string elements "Name 1" and "Name 2"?
• What will be printed by the two showMe() calls on the Data class, the first with an integer argument 10 and the second with the string argument 'Z'?
• What will be printed when iterating a two-dimensional array {{1,2,3},{4,5}} with a nested loop that prints elements and breaks the inner loop when an element equals 2, followed by a continue for the outer loop?
• Which is correct format of writing JSON name/value pair?
• Which statement will throw a NullPointerException when executed?
• Which statement will cause the Travel.go() method to compile? public class Travel { ArrayList<Hotel> go() { // insert code here } }
• What does Java serialization do?
• In a ragged two-dimensional array declared as int[][] a = new int[2][]; a[0] = new int[3]; a[1] = new int[2]; What is a[1].length?
• If a String d initially holds 'bookkeeper', you call substring(1,7) but do not assign the result, then set d to 'w' + d, and then call append on d; what happens?
• In the given Java snippet, the line creating an ObjectOutputStream uses ObjectOutputstream (lowercase s). What is the result?
• Given a class A with a method baz and a subclass B that overrides baz, what is the result when you execute A a = new B(); a.baz()?
• Which practice most improves Java performance by reducing boxing and unnecessary synchronization?
• What is the main purpose of the double-checked locking pattern with volatile in lazy initialization?
• Which statement about interfaces and inheritance in Java is correct?
• Which import statement is required to use ArrayList in Java?
• Consider a snippet that creates a StringBuilder sb with '12345678', sets its length to 5, then attempts to set length to 10, and then prints sb.length() with an invalid argument; will it compile?
• What is the behavior of a static field in a class?
• Given i = 0 and j = 11, after a loop that decrements j and increments i in the condition, what is printed?
• Which pattern is commonly used for thread-safe lazy initialization using a static inner class?
• Which statement is true about eager initialization of a singleton?
• After executing sb = new StringBuilder('12345678'); sb.setLength(5); sb.setLength(10); what is sb.length()?
• Which line can be added to the following class to ensure the final boolean field is properly initialized so the code compiles? public class InitTest { static int si = 10; int i; final boolean bool; // 1 }
• Which class is used to read characters from a text file?
• Which annotation is used to indicate that a method overrides a method in a superclass?
• If s1 is assigned 'abc', s2 is assigned 'def', s3 is set to s2, then s2 is changed to 'ghi'; what is printed when concatenating s1, s2, and s3?
• If you reassign a parameter that holds an object reference inside a method, does the original reference in the caller change?
• Can null value be added to a List?
• Which tool is used to execute Java code?
• If the code compiles and reaches the try block, what will be printed?
• Which pairing is a typical combination in the Java Collections Framework?
• What does File.length() return?
• Which of the following demonstrates polymorphism?
• Explain fail fast versus fail safe iterators with examples.
• Which statement correctly describes the differences among String, StringBuilder, and StringBuffer?
• Which feature of java.util.concurrent Locks allows configuring thread acquisition order?
• In Java, how are primitive arguments passed to methods?
• What does List<? extends Number> mean for type safety?
• What happens to the monitor when a thread calls wait() on an object?
• Which operator or keyword is used to determine the type of an object at runtime in Java?
• Which statement best describes type erasure in Java generics?
• What was the earlier name of the Java programming language?
• Which of the following is considered a common SQL anti-pattern in Java applications?
• What will happen when adding null to a List<Integer> and then summing with auto-unboxing?
• What is the value of a[3] for the array int[] a = {1, 2, 3, 4};
• How can Java achieve multiple inheritance?
• In Java, what are the results of the following comparison: a = new String('x'); b = new String('x'); System.out.println(a == b); System.out.println(a.equals(b));
• Which statement about inheritance in Java is true?
• JSON stands for which of the following?
• Which statement about lambda expressions is true?
• After execution of the code fragment where int x, a = 6, b = 7; x = a++ + b++; what are the values of x, a, and b?
• What is the default value of each element in a newly created int[] array?
• Which of the following is a valid JSON representation for an object with name 'Alice' ?
• Which of the following command sequences will compile a Java class named MyFirstClass and run it with the arguments hello and hello?
• What will happen when you compile and run code that prints a five-element int array where no values are assigned?
• In Java, what is the difference between the equality operator and the equals method?
• What is printed by the following Java code snippet? int[] ar = new int[5]; for (int i = 0; i < ar.length; i++) System.out.print(ar[i]);
• Which of the following is a valid way to declare a String with content 'Hello'?
• Which statement about interfaces best describes their role?
• Which statement about ObjectOutputStream's writeObject method is true?
• Which command prints Hello! when run with the arguments open and someone?
• In a scenario with nested loops, if the inner loop runs three times for each outer iteration, how many total inner iterations occur across all outer iterations?
• Which statement about Runnable and Callable is correct?
• In a two-dimensional array example where the inner loop breaks on the value 2, what is the printed sequence?
• What is the result of evaluating the following expression? String s = "ab"; String t = "a" + "b"; System.out.println(s == t);
• Which JDBC interface is used to call stored procedures?
• Which characteristic defines a functional interface in Java?
• What is the result of the following primes code, considering the line 'List p = = new ArrayList();' is in the program?
• Which of the following is not a primitive data type in Java?
• Which memory area in the JVM stores Java objects?
• Which File method tests the existence of a file or directory?
• Which expression correctly provides a default value using Optional when x might be null?
• What is the result of the expression new String("Hello").equals("Hello")?
• Which line creates an Employee instance?
• How many times will the value 2 be printed in a nested loop where the outer loop iterates over three elements and the inner loop runs with a counter from 0 to 2 for each element?
• If a method assigns its String parameter to a new value, does the original variable in the caller reflect that change?
• What is the purpose of a database connection pool?
• What is the key difference between map() and flatMap() in Java Streams?
• To use FileReader and BufferedReader, which import is necessary?
• In the following Java code, which lines are printed? for (int i = 0; i < 2; i++) { for (int j = 0; j < 3; j++) { if (i == j) { continue; } System.out.println("i = " + i + " j " + j); } }
• Given the following code, what is the result when compiling and running? A subclass attempts to override a method with a different primitive return type, and the code uses the subclass instance to call the method.
• Which statement accurately describes PreparedStatement in JDBC?
• In Java, which statement best describes the difference between shallow copies and deep copies?
• Which of the following keywords cannot be used when declaring a class?
• In Java Streams, which operation is terminal and triggers evaluation?
• What value is printed by the program that initializes var to 20 and uses a do-while with inner loops, finally printing var?
• Which technique can help prevent deadlocks by using a timeout when acquiring locks?
• Which statement best describes Dependency Injection and how a DI container works in Spring (basic)?
• Which package contains the File class?
• Which statement about try-with-resources with multiple resources is true?
• Consider a class that declares int[] ia = new int[1]; Object[] oA = new Object[1]; boolean bool; and prints ia[0] + ' ' + oA[0] + bool. What is the printed result?
• From a Java perspective, which statement best contrasts REST and SOAP web services?
• Which method is used to call the constructors of the superclass from the subclass?
• Given a = 5 and b = 9; x = a++ + b++; what are x, a, b after the expression?
• Which class is used to write objects to a file?
• Which statement best describes inheritance in Java?
• If a static int field is declared but not initialized, what is its default value?
• Which keyword is used to create an instance of a class?
• Is String considered a wrapper class in Java?
• In a class SomeClass with methods of varying access modifiers, which set of method calls from another class in the same package are valid?
• In a Java program where i is initialized to 10 and a static variable j is initialized to 20, a method doubles its parameter and doubles j. After calling the method with i, what values are printed for i and j?
• What does System.out.println(5 + 3); print?
• What is the value of d after calling substring(1,7) on the string 'bookkeeper' if the returned value is not assigned to any variable?
• What is the default access modifier for an interface method?
• Which exception is typically caught for I/O operations in Java?
• What is the difference between HashMap and ConcurrentHashMap?
• String[] seasons = {"winter", "spring", "summer", "fall"}; What is seasons.length?
• Which method reads a line of text from a BufferedReader?
• Given a List<String> al that has two elements added, what is al.size()?
• Which statement makes a class serializable?
• What is autoboxing and unboxing in Java, and what are potential performance implications?
• If b starts as 8 and c starts as 3, what is the value of b after performing b = (byte) (b ^ c)?
• Who is considered the father of the Java programming language?
• Which statement best characterize a deep copy?
• Which declaration would allow the code that uses a 2D List named table to compile when inserting at the designated declaration point?
• Which statement is true about primitive types and wrapper classes in the context of autoboxing?
• Which Java class is a widely used example of immutability?
• What is printed when running a program with no command-line arguments that computes k = m1(args.length); k += 3 + ++k; System.out.println(k);?
• Consider the following code snippet: StringBuffer s = new StringBuffer("Hello"); if ((s.length() > 5) && s.append("there").equals("Fa1se")); // do nothing System.out.println("value is " + s); What is the output?
• What is the output of this code fragment? int x = 3; int y = 10; System.out.println(y % x);
• In a do-while loop, which statement best describes how many times the loop body is executed?
• In a loop that contains a break inside the inner loop, which loop is terminated by the break?
• Which Optional expression correctly transforms a present value using a map to lower case?
• Which declaration initializes an array in a single statement with five elements?
• Which statement best describes encapsulation with a simple example?
• Which statement is true about comparing arrays with Arrays.equals(a, b) versus using a.equals(b)?
• Given the snippet: String s = "Hello"; if (s.length() > 5) { s += "There"; } System.out.println("value is " + s); What is printed?
• What is the value of j after executing the following? int i = 0; int j = i++ + ++i; System.out.println(j);
• Given the method skeleton with invalid syntax in Java, such as int radix 2; and misused else blocks, what is the result of compiling this method?
• JSON stands for JavaScript Object Notation.
• What will the following program print? The variable c starts at 0 and a flag is true; within a loop the counter increments until certain conditions deactivate the flag. What is printed?
• Which statement describes try-with-resources in Java?
• If a subclass overrides a method and an object is referenced by its superclass type, which implementation is executed at runtime?
• Which statement about volatile variables is false?
• In the example where a static integer a is initialized to 40, what is printed by the program?
• What are the default values for elements of int[] and boolean[] when a new array is created in Java?
• Which statement about abstract methods is true?
• In Java, attempting to override a method in a subclass by changing its primitive return type results in what?
• If the serialVersionUID of a class changes and you attempt to deserialize an older serialized form, what happens?
• In Java, what is the purpose of the super keyword in a subclass constructor?
• In the Computer class, the field k is declared as a Keyboard and initialized with new Keyboard(). This demonstrates what concept?
• Which singleton pattern is most resistant to reflection attacks and serialization issues?
• Given a superclass with a constructor Dog(String name) and a subclass Beagle that defines only one constructor, which Beagle constructor would be legal?
• If a program defines s as 'hello' (String) and sb as StringBuilder('hello'), then sb.reverse() is called and s.reverse() is attempted; what happens?
• Which statement about List, Set, and Map is correct?
• Which statement about comparing arrays with the operator '==' is true?
• What is printed when the following method is invoked with an argument 4?
• Which technique is commonly used to implement pagination in JDBC queries?
• Consider the code snippet: int arr[2]; System.out.println(arr[0]); System.out.println(arr[1]); What happens when compiling and running this code in Java?
• If an array has length n, what is the index of its last element?
• Which statement correctly describes method overloading?
• Which statement about protected access in Java is true?
• When do Java static initialization blocks execute?
• Which checked exception must be handled or declared when performing file I/O operations in Java?
• Can you extend an interface in Java?
• What happens if you try to instantiate an abstract class?
• Which statement about garbage collection in Java is correct?
• What results from running the following code where b is 10 and c is 15, and b is assigned as (byte) (b ^ c)?
• Which statement about the default constructor in Java is true?
• Which statement correctly describes typical error handling for file I/O in Java?
• When overriding a method, which statement is true about its visibility?
• Given this code: int x = 0, y = 4, z = 5; if (x > 2) { if (y < 5) { System.out.println("message one"); } else { System.out.println("message two"); } } else if (z > 5) { System.out.println("message three"); } else { System.out.println("message four"); } What is printed?
• After the method returns, what value is printed for the original int variable in the caller when printing it in main?
• Can an abstract class be declared final?
• Which statement about static fields is true?
• Which statement correctly describes checked versus unchecked exceptions in Java?
• What is true about static fields in Java?
• Which statement best describes volatile variables in Java in terms of visibility and ordering?
• In a nested loop that builds 11 rows (i from 0 to 10) each row containing 11 elements (j from 0 to 10), how many elements are in each inner row?
• Assuming the declarations int i = 10, j = 12, k = 1; k += i++ - --j; what is the value printed for k?
• Which option is commonly used to read a string from standard input in Java?
• Which Map implementation maintains keys in natural order or by a comparator?
• Which statement about reading and writing files with NIO is true?
• Which technique is commonly used to perform a deep copy by converting an object graph to a byte stream and back?
• Which class declaration is valid in a Java file named Example.java?
• Which statement accurately reflects the equals/hashCode contract?
• Which feature was introduced in Java 9 as part of the module system?
• What is the difference between default methods in interfaces and abstract classes in Java?
• Given int[] a = {1, 2, 3}; int[] b = {1, 2, 3}; System.out.println(a == b);
• When used as a stack or queue, which statement is most accurate?
• Which statement best describes how Java passes arguments to methods?
• Given two strings created as follows: String s1 = "abc" + "def"; String s2 = new String(s1); Which statement is true?
• Given int[] arr = new int[3]; System.out.println(arr.length); What is printed?
• Given the following switch structure, what is printed when i equals 5? switch (i) { default: case 1: System.out.println(1); case 0: System.out.println(0); case 2: System.out.println(2); break; case 3: System.out.println(3); }
• What is the output of the following snippet: int a=1; int b=a++; int c=++a; System.out.println(a + " " + b + " " + c);
• Which statement about the modulo operator is true in Java?
• Given two int arrays arr1 and arr2 initialized as {1, 2, 3} and {1, 2, 3} respectively, what is the result of Arrays.equals(arr1, arr2) in Java?
• Which class is used to write primitive data types to a stream in Java?
• Which statement about Java wrapper types like Integer is true?
• Which description best captures the Java Collections Framework?
• What is a key advantage of Lock over synchronized blocks in Java?
• Which of the following is a valid way to declare an array in Java?
• Which constructor initializes x when given an integer argument?
• Given a superclass MySuper with a constructor that prints values and a subclass MySub that calls super(2) and then prints, what is the output when creating a new MySub()?
• For the following program snippet, what happens when run with the command line arguments java Test closed?
• Which of the following is a valid JSON object literal with name Bob and age 30?
• Which statement is true about serialization of transient and static fields in Java?
• Which statement accurately describes immutability in Java?
• Which statement best describes the compilation result of the code snippet that initializes an integer with syntax int k 2; while(--k) { System.out.println(k); } ?
• When two int variables are passed to a method that attempts to swap their values by parameter, which statement is true?
• If a class has a static int count initialized to 0, and its constructor increments count, what is the printed value after creating three objects and printing count?
• Assume a Java program declares int size = 10; int[] arr = new int[size]; and prints each element in sequence with no separators. Without any assignment to arr, what is printed?
• Which statement about Java Streams is true?
• Which memory area in the JVM stores loaded class metadata?
• What is a primary benefit of using a thread pool in Java?
• How does ArrayList resize when its capacity is reached?
• Which approach is commonly used to expose different API versions in RESTful URLs?
• Which statement about Path and Files APIs is true?
• Which keyword is used to inherit a class?
• What is the primary purpose of serialVersionUID in Java serialization?
• Which statement best describes the goal of the G1 garbage collector?
• Which statement is the canonical Java main method signature for the program entry point?
• Which RESTful practice is specifically aimed at enabling efficient client-side caching?
• Which constructor initializes y when given a string argument?
• What does List.subList(int fromIndex, int toIndex) return?
• Which declaration initializes an array in a single statement with exactly five elements?
• Which statement best describes the difference between character streams and byte streams in Java?