Java Basics and Syntax

A method is declared as: public void setAge(int age) { this.age = age; } Which statement is correct about this code assuming the class has an instance variable age?

Which method overloading is valid?

A developer uses the following array initialization: int[] nums = new int[]{1, 2, 3}; Which of the following is true?

Arrange the steps to use the Scanner class to read user input in Java in the correct order.

Given the loop: for (int i=0; i<5; i++) { if (i==2) continue; System.out.print(i); } What is the output?

Given method: static void change(String s) { s = "new"; } What is output of: String name = "original"; change(name); System.out.println(name);

Which TWO of the following are valid Java identifiers?

Arrange the steps to declare and initialize a one-dimensional array in Java in the correct order.

What is the result of the expression 10 % 3?

Which statement about try-catch is true?

What is the output of this program?

Which TWO keywords are used for decision-making in Java? (Choose two.)

A subclass overrides a method from its superclass. Which annotation should be used to indicate the overriding intention?

A team decides to use a single Java source file for a small application. Which statement is true about the file structure?

Which TWO are valid Java identifiers? (Choose two.)

Which TWO statements about constructors are true? (Choose two.)

Which assignment requires an explicit cast to compile?

A financial trading application processes high-volume transactions. The system uses a multithreaded architecture where multiple threads update a shared Account object's balance field. Recently, intermittently incorrect balance calculations have been reported. Developers suspect a race condition on the balance field. The Account class is defined as follows: public class Account { private double balance = 0.0; public void deposit(double amount) { balance += amount; } public void withdraw(double amount) { balance -= amount; } public double getBalance() { return balance; } } Threads are created using ExecutorService with a fixed thread pool. The issue occurs only under heavy load. Which course of action should the development team take to resolve the issue while maintaining performance?

What is the result of compiling and running this code?

Which TWO are valid ways to create a String object?

Refer to the exhibit. What is the output?

Which THREE are primitive data types in Java? (Choose three.)

A developer is writing a program to find the maximum value in an array of integers. The code is: int[] nums = {10, 20, 5, 30, 15}; int max = 0; for (int i = 0; i < nums.length; i++) { if (nums[i] > max) { max = nums[i]; } } System.out.println(max); The output is 30, which is correct for this array. However, the developer is concerned that if all numbers are negative, the output would be 0 instead of the highest negative number. Which modification ensures the algorithm works correctly for all integer arrays?

A method receives an int parameter and modifies its value inside the method. Does this change affect the caller's argument?

Which access modifier allows members to be accessed only by classes in the same package?

Which TWO of the following are valid Java identifiers? (Choose two.)

Refer to the exhibit. What is the likely cause of this error?

Which THREE are valid ways to declare and initialize an integer variable in Java? (Choose three.)

Given two String objects s1 = "Hello" and s2 = "Hello", what does the expression (s1 == s2) return?

Which is the correct way to declare an array of integers in Java?

Which THREE of the following are primitive data types in Java?

Which loop construct guarantees that the body executes at least once?

A method is declared as: public static void main(String[] args) { }. Which statement is true?

Which TWO of the following are legal ways to declare and initialize an array?

Which TWO statements are true about the main method?

A developer declares an integer variable inside a method but does not assign a value. What is the result of attempting to print the variable?

A developer writes code to calculate the average of two integers: int a = 5; int b = 10; int avg = a / b;. Which change ensures the average is correctly calculated as a double?

Which access modifier makes a member visible only within its own class?

Given: String s = "Java"; s.concat(" Rocks"); System.out.println(s); What prints?

A class defines a static variable initialized at declaration: static int count = 10;. A static method attempts to modify it: count = 20;. Which statement is true?

The code does not compile. What is the error?

A method is expected to receive an integer and return its square. Which method signature is correct?

Given: int day = 3; switch(day) { case 1: System.out.print("A"); case 2: System.out.print("B"); case 3: System.out.print("C"); case 4: System.out.print("D"); } What prints?

You are developing a Java application for a library management system. The system must track the number of books in each genre. You need to store genre names (String) and their counts (int). The data will be accessed frequently and modified rarely. Which Java data structure should you use to store this mapping efficiently, while ensuring that genre names are unique?

A junior developer wrote the following code to calculate the sum of an array: int[] numbers = {1, 2, 3, 4, 5}; int sum = 0; for (int i = 1; i <= numbers.length; i++) { sum += numbers[i]; } System.out.println("Sum: " + sum); The developer expects the output to be 15, but the program throws an exception. What is the root cause and the correct fix?

A team is developing a library management system. They have a base class 'Item' with a method 'getTitle()' that returns the title. They also have a subclass 'Book' that overrides 'getTitle()'. In some places, they have a method that accepts an Item reference but actually receives a Book object. They want to call a method specific to Book, such as 'getISBN()', that is not in Item. They attempt to cast the parameter: ((Book) item).getISBN(). However, occasionally the program crashes with ClassCastException. What is the best practice to avoid this exception?

A class defines two methods with the same name but different parameter lists. This is known as:

A class has a static variable counter initialized to 0. Two threads increment counter 1000 times each using counter++. What is a possible final value of counter?

A mobile app backend uses Java streams to process user data. The code snippet filters users who are active and older than 18, then collects them into a list: List<User> result = users.stream() .filter(u -> u.isActive()) .filter(u -> u.getAge() > 18) .collect(Collectors.toList()); Performance metrics show that this stream operation is slow when the user list has millions of entries. The team wants to improve performance without changing the business logic. Which change would most likely improve performance?

A web application uses a HashMap to cache user session data. The keys are String objects representing session IDs, and values are Session objects. After some time, the cache memory usage grows excessively, causing OutOfMemoryError. The cache is never cleared. The team decides to implement a cache eviction policy. Which approach is best suited for this scenario in terms of Java standard library?

Given methods: void print(Integer i) { System.out.println("Integer"); } void print(int i) { System.out.println("int"); } What is output of print(10);?

Which THREE are valid Java identifiers?

Refer to the exhibit. What is the result of attempting to compile and run the code?

Consider: for(int i=0;i<10;i++) { int x = i; } System.out.println(x); What is the result?

A package named com.example.util is declared in a file. Where should the file be placed in the directory structure?

A parent class has a static method display() and an instance method show(). A child class attempts to override both. What is the outcome?

Given the code: String s1 = "Java"; String s2 = new String("Java"); if (s1 == s2) { System.out.print("Equal"); } else { System.out.print("Not Equal"); } What is the output?

Which loop construct guarantees that the loop body executes at least once?

Given: int[] arr = {10,20,30}; System.out.println(arr[3]); What is the result?

A developer wants to iterate over an array of integers named 'numbers'. Which loop declaration will correctly access each element?

Which THREE statements about the final keyword in Java are true?

A developer writes the following code: int x = 5; int y = x++; What are the values of x and y after execution?

Refer to the exhibit. What is the output?

Which THREE are valid ways to declare and initialize a two-dimensional int array in Java?

Refer to the exhibit. What is the output?

What likely caused this compilation error?

Match each Java collection interface to its characteristics.

A company requires a method that accepts an integer and returns true if the integer is even, otherwise false. Which implementation best follows Java conventions?

Which THREE of the following are primitive data types in Java?

Refer to the exhibit. What happens when you compile this code?

What is the value printed?

Refer to the exhibit. What is the most likely cause?

A developer writes the following code to compare two strings: String s1 = "Java"; String s2 = new String("Java"); if (s1 == s2) { System.out.println("Equal"); } else { System.out.println("Not equal"); } What is the output?

Which TWO are valid identifiers in Java? (Choose two.)

Match each access modifier to its visibility level.

Refer to the exhibit. What is the output?

Which primitive data type should be used to store a single character?

You are writing a program that processes a list of transactions. Each transaction has a timestamp (long), amount (double), and type (String). The program needs to iterate through the transactions in the order they were added. Which collection should you use to maintain insertion order and allow fast iteration?

Given the following code: class A { A() { System.out.print("A "); } } class B extends A { B() { System.out.print("B "); } } class C extends B { C() { System.out.print("C"); } public static void main(String[] args) { new C(); } } What is the output when running the main method?

What is the result of: Integer a = null; int b = (a != null) ? a : 0; System.out.println(b);

A developer writes: int x = 5; int y = x++ + ++x; What is the value of y after execution?

A developer writes: if (x = 5) { System.out.println("x is 5"); } What is the result?

Which TWO keywords are used to control access to class members? (Choose two.)

What is the result of: int[] arr = new int[5]; System.out.println(arr[5]);

Which data type should be used to store a single character like 'A'?

A developer is working on a Java application that processes user input. The application reads an integer from the command line using args[0], converts it to an int, and uses it in a loop. When testing, the application throws a NumberFormatException when the user provides an alphabetic string. The developer needs to handle this exception gracefully by prompting the user to enter a valid number and retrying. However, the developer must avoid infinite loops. The current code uses a while loop with a flag. Which approach ensures the code handles the exception, provides feedback, and terminates if the user enters 'quit'? The environment is a standard Java SE 11 application. The developer wants a robust solution without using external libraries.

Given the code: int[] arr = {1,2,3}; for(int x : arr) { if(x==2) continue; System.out.print(x); } What is the output?

Which THREE are primitive data types in Java? (Choose three.)

A developer writes the following code: int x = 5; System.out.println(x++); What is the output?

What is the result of the following code? String s1 = "Hello"; String s2 = " World"; String s3 = s1 + s2; System.out.println(s3);

Given int[] arr = {1,2,3}; which correctly creates a new array with length 5 and copies the contents of arr?

What is the scope of a variable declared inside a for loop?

What is the output? ```java public class Test { public static void main(String[] args) { String s1 = "hello"; String s2 = "hello"; System.out.println(s1.equals(s2)); } } ```

What is the value of the expression (10 > 5) && (3 < 2)?

A developer writes: int x; System.out.println(x); What is the result?

A developer uses a switch statement with a String variable. Which is true about this usage?