Java Programming Placement Questions

Last Updated: March 2026

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Introduction

Java remains one of the most popular and widely-used programming languages in the industry. Its platform independence, robust standard library, and strong object-oriented features make it a favorite among companies like Infosys, TCS, Wipro, Cognizant, Accenture, Capgemini, and many product-based companies. Java is extensively tested in placement exams for its OOP concepts, collections framework, multithreading, and exception handling.

Why Java is Important for Placements

1. Industry Standard: Widely used in enterprise applications, Android development, and web services
2. OOP Mastery: Pure object-oriented language testing OOP understanding
3. Platform Independence: Write Once, Run Anywhere philosophy
4. Rich Ecosystem: Extensive libraries and frameworks (Spring, Hibernate)
5. Strong Community: Abundant resources and documentation

Companies Testing Java Programming

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Frequently Asked Coding Questions with Solutions

Question 1: Class and Object Implementation

Problem: Create a BankAccount class with deposit, withdrawal, and balance check functionality.

Solution:

class BankAccount {
    private String accountNumber;
    private String accountHolder;
    private double balance;
    
    // Constructor
    public BankAccount(String accNum, String holder, double initialBalance) {
        this.accountNumber = accNum;
        this.accountHolder = holder;
        this.balance = initialBalance;
    }
    
    // Deposit method
    public void deposit(double amount) {
        if (amount > 0) {
            balance += amount;
            System.out.println("Deposited: $" + amount);
        } else {
            System.out.println("Invalid deposit amount");
        }
    }
    
    // Withdraw method
    public boolean withdraw(double amount) {
        if (amount > 0 && amount <= balance) {
            balance -= amount;
            System.out.println("Withdrawn: $" + amount);
            return true;
        } else {
            System.out.println("Insufficient funds or invalid amount");
            return false;
        }
    }
    
    // Get balance
    public double getBalance() {
        return balance;
    }
    
    // Display account info
    public void displayInfo() {
        System.out.println("Account: " + accountNumber);
        System.out.println("Holder: " + accountHolder);
        System.out.println("Balance: $" + balance);
    }
}

public class BankingSystem {
    public static void main(String[] args) {
        BankAccount account = new BankAccount("ACC001", "John Doe", 1000.0);
        
        account.displayInfo();
        System.out.println();
        
        account.deposit(500.0);
        account.withdraw(200.0);
        
        System.out.println();
        System.out.println("Current Balance: $" + account.getBalance());
    }
}

Output:

Account: ACC001
Holder: John Doe
Balance: $1000.0

Deposited: $500.0
Withdrawn: $200.0

Current Balance: $1300.0

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Question 2: Inheritance and Method Overriding

Problem: Demonstrate inheritance with Employee as parent and Manager/Developer as child classes.

Solution:

// Parent class
class Employee {
    protected String name;
    protected int id;
    protected double salary;
    
    public Employee(String name, int id, double salary) {
        this.name = name;
        this.id = id;
        this.salary = salary;
    }
    
    public void work() {
        System.out.println(name + " is working");
    }
    
    public double calculateBonus() {
        return salary * 0.10;
    }
    
    public void displayInfo() {
        System.out.println("ID: " + id + ", Name: " + name);
        System.out.println("Salary: $" + salary);
    }
}

// Child class - Manager
class Manager extends Employee {
    private int teamSize;
    
    public Manager(String name, int id, double salary, int teamSize) {
        super(name, id, salary);
        this.teamSize = teamSize;
    }
    
    @Override
    public void work() {
        System.out.println(name + " is managing a team of " + teamSize);
    }
    
    @Override
    public double calculateBonus() {
        return salary * 0.20; // 20% bonus
    }
    
    public void conductMeeting() {
        System.out.println(name + " is conducting a team meeting");
    }
}

// Child class - Developer
class Developer extends Employee {
    private String programmingLanguage;
    
    public Developer(String name, int id, double salary, String lang) {
        super(name, id, salary);
        this.programmingLanguage = lang;
    }
    
    @Override
    public void work() {
        System.out.println(name + " is coding in " + programmingLanguage);
    }
    
    @Override
    public double calculateBonus() {
        return salary * 0.15; // 15% bonus
    }
    
    public void debugCode() {
        System.out.println(name + " is debugging code");
    }
}

public class CompanySystem {
    public static void main(String[] args) {
        Manager manager = new Manager("Alice", 101, 80000, 10);
        Developer developer = new Developer("Bob", 102, 60000, "Java");
        
        System.out.println("=== Manager ===");
        manager.displayInfo();
        manager.work();
        System.out.println("Bonus: $" + manager.calculateBonus());
        manager.conductMeeting();
        
        System.out.println("\n=== Developer ===");
        developer.displayInfo();
        developer.work();
        System.out.println("Bonus: $" + developer.calculateBonus());
        developer.debugCode();
    }
}

Output:

=== Manager ===
ID: 101, Name: Alice
Salary: $80000.0
Alice is managing a team of 10
Bonus: $16000.0
Alice is conducting a team meeting

=== Developer ===
ID: 102, Name: Bob
Salary: $60000.0
Bob is coding in Java
Bonus: $9000.0
Bob is debugging code

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Question 3: Interface Implementation

Problem: Create interfaces and demonstrate multiple interface implementation.

Solution:

// Interface 1
interface Drawable {
    void draw();
    default void print() {
        System.out.println("Printing...");
    }
}

// Interface 2
interface Resizable {
    void resize(double factor);
}

// Interface 3
interface Movable {
    void move(int x, int y);
}

// Class implementing multiple interfaces
class Rectangle implements Drawable, Resizable, Movable {
    private double width;
    private double height;
    private int x, y;
    
    public Rectangle(double w, double h) {
        this.width = w;
        this.height = h;
        this.x = 0;
        this.y = 0;
    }
    
    @Override
    public void draw() {
        System.out.println("Drawing rectangle: " + width + " x " + height);
    }
    
    @Override
    public void resize(double factor) {
        width *= factor;
        height *= factor;
        System.out.println("Resized to: " + width + " x " + height);
    }
    
    @Override
    public void move(int newX, int newY) {
        x = newX;
        y = newY;
        System.out.println("Moved to position: (" + x + ", " + y + ")");
    }
    
    public double getArea() {
        return width * height;
    }
}

public class InterfaceDemo {
    public static void main(String[] args) {
        Rectangle rect = new Rectangle(10, 20);
        
        rect.draw();
        rect.move(5, 10);
        rect.resize(1.5);
        System.out.println("Area: " + rect.getArea());
        rect.print(); // Default method from Drawable
    }
}

Output:

Drawing rectangle: 10.0 x 20.0
Moved to position: (5, 10)
Resized to: 15.0 x 30.0
Area: 450.0
Printing...

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Question 4: ArrayList Operations

Problem: Demonstrate ArrayList operations with custom objects.

Solution:

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.Iterator;

class Student implements Comparable<Student> {
    private String name;
    private int rollNumber;
    private double marks;
    
    public Student(String name, int roll, double marks) {
        this.name = name;
        this.rollNumber = roll;
        this.marks = marks;
    }
    
    public String getName() { return name; }
    public int getRollNumber() { return rollNumber; }
    public double getMarks() { return marks; }
    
    @Override
    public int compareTo(Student other) {
        return this.rollNumber - other.rollNumber;
    }
    
    @Override
    public String toString() {
        return rollNumber + ": " + name + " (" + marks + ")";
    }
}

public class ArrayListDemo {
    public static void main(String[] args) {
        ArrayList<Student> students = new ArrayList<>();
        
        // Adding elements
        students.add(new Student("Alice", 103, 85.5));
        students.add(new Student("Bob", 101, 90.0));
        students.add(new Student("Charlie", 102, 78.5));
        
        System.out.println("=== Original List ===");
        for (Student s : students) {
            System.out.println(s);
        }
        
        // Sort by roll number (using Comparable)
        Collections.sort(students);
        System.out.println("\n=== Sorted by Roll Number ===");
        for (Student s : students) {
            System.out.println(s);
        }
        
        // Sort by marks (using Comparator)
        students.sort(Comparator.comparingDouble(Student::getMarks).reversed());
        System.out.println("\n=== Sorted by Marks (Desc) ===");
        for (Student s : students) {
            System.out.println(s);
        }
        
        // Find student with highest marks
        Student topStudent = Collections.max(students, Comparator.comparingDouble(Student::getMarks));
        System.out.println("\nTop Student: " + topStudent);
    }
}

Output:

=== Original List ===
103: Alice (85.5)
101: Bob (90.0)
102: Charlie (78.5)

=== Sorted by Roll Number ===
101: Bob (90.0)
102: Charlie (78.5)
103: Alice (85.5)

=== Sorted by Marks (Desc) ===
101: Bob (90.0)
103: Alice (85.5)
102: Charlie (78.5)

Top Student: 101: Bob (90.0)

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Question 5: HashMap Usage

Problem: Count word frequencies using HashMap.

Solution:

import java.util.HashMap;
import java.util.Map;

public class WordFrequency {
    public static void main(String[] args) {
        String text = "the quick brown fox jumps over the lazy dog the fox was quick";
        
        // Split into words
        String[] words = text.toLowerCase().split("\\s+");
        
        // Count frequencies
        HashMap<String, Integer> frequencyMap = new HashMap<>();
        
        for (String word : words) {
            frequencyMap.put(word, frequencyMap.getOrDefault(word, 0) + 1);
        }
        
        // Display results
        System.out.println("=== Word Frequencies ===");
        for (Map.Entry<String, Integer> entry : frequencyMap.entrySet()) {
            System.out.println(entry.getKey() + ": " + entry.getValue());
        }
        
        // Find most frequent word
        String mostFrequent = "";
        int maxCount = 0;
        
        for (Map.Entry<String, Integer> entry : frequencyMap.entrySet()) {
            if (entry.getValue() > maxCount) {
                maxCount = entry.getValue();
                mostFrequent = entry.getKey();
            }
        }
        
        System.out.println("\nMost frequent word: '" + mostFrequent + "' (appears " + maxCount + " times)");
        
        // Check if word exists
        if (frequencyMap.containsKey("fox")) {
            System.out.println("'fox' appears " + frequencyMap.get("fox") + " times");
        }
    }
}

Output:

=== Word Frequencies ===
the: 3
quick: 2
brown: 1
fox: 2
jumps: 1
over: 1
lazy: 1
dog: 1
was: 1

Most frequent word: 'the' (appears 3 times)
'fox' appears 2 times

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Question 6: Exception Handling

Problem: Demonstrate custom exception and exception handling.

Solution:

// Custom exception
class InsufficientFundsException extends Exception {
    public InsufficientFundsException(String message) {
        super(message);
    }
}

class InvalidAmountException extends RuntimeException {
    public InvalidAmountException(String message) {
        super(message);
    }
}

class BankAccount {
    private double balance;
    
    public BankAccount(double initialBalance) {
        this.balance = initialBalance;
    }
    
    public void withdraw(double amount) throws InsufficientFundsException {
        if (amount <= 0) {
            throw new InvalidAmountException("Amount must be positive");
        }
        if (amount > balance) {
            throw new InsufficientFundsException("Insufficient funds. Balance: $" + balance);
        }
        balance -= amount;
        System.out.println("Withdrawn: $" + amount);
    }
    
    public double getBalance() {
        return balance;
    }
}

public class ExceptionDemo {
    public static void main(String[] args) {
        BankAccount account = new BankAccount(1000.0);
        
        // Test 1: Normal withdrawal
        try {
            account.withdraw(500.0);
            System.out.println("Balance: $" + account.getBalance());
        } catch (InsufficientFundsException e) {
            System.out.println("Error: " + e.getMessage());
        }
        
        // Test 2: Insufficient funds
        try {
            account.withdraw(1000.0);
        } catch (InsufficientFundsException e) {
            System.out.println("Error: " + e.getMessage());
        }
        
        // Test 3: Invalid amount (runtime exception)
        try {
            account.withdraw(-100.0);
        } catch (InsufficientFundsException e) {
            System.out.println("Error: " + e.getMessage());
        } catch (InvalidAmountException e) {
            System.out.println("Error: " + e.getMessage());
        }
        
        System.out.println("\nProgram continues normally...");
    }
}

Output:

Withdrawn: $500.0
Balance: $500.0
Error: Insufficient funds. Balance: $500.0
Error: Amount must be positive

Program continues normally...

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Question 7: String Manipulation

Problem: Demonstrate various String operations.

Solution:

public class StringOperations {
    public static void main(String[] args) {
        String str = "  Hello, World! Welcome to Java  ";
        
        // Basic operations
        System.out.println("Original: '" + str + "'");
        System.out.println("Trimmed: '" + str.trim() + "'");
        System.out.println("Length: " + str.length());
        System.out.println("Uppercase: " + str.toUpperCase());
        System.out.println("Lowercase: " + str.toLowerCase());
        
        // Substring
        String substring = str.substring(10, 15);
        System.out.println("Substring (10,15): '" + substring + "'");
        
        // Replace
        String replaced = str.replace("World", "Java");
        System.out.println("Replaced: " + replaced);
        
        // Split
        String[] words = str.trim().split("\\s+");
        System.out.println("\nWords count: " + words.length);
        for (String word : words) {
            System.out.println("- " + word);
        }
        
        // StringBuilder for mutable strings
        StringBuilder sb = new StringBuilder();
        sb.append("Java");
        sb.append(" is");
        sb.append(" awesome");
        System.out.println("\nStringBuilder: " + sb.toString());
        
        sb.reverse();
        System.out.println("Reversed: " + sb.toString());
        
        // Check palindrome
        String palindrome = "racecar";
        boolean isPalindrome = new StringBuilder(palindrome).reverse().toString().equals(palindrome);
        System.out.println("\n'" + palindrome + "' is palindrome: " + isPalindrome);
    }
}

Output:

Original: '  Hello, World! Welcome to Java  '
Trimmed: 'Hello, World! Welcome to Java'
Length: 33
Uppercase: '  HELLO, WORLD! WELCOME TO JAVA  '
Lowercase: '  hello, world! welcome to java  '
Substring (10,15): 'orld!'
Replaced:   Hello, Java! Welcome to Java  

Words count: 5
- Hello,
- World!
- Welcome
- to
- Java

StringBuilder: Java is awesome
Reversed: emosewa si avaJ

'racecar' is palindrome: true

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Question 8: Multithreading Basics

Problem: Create and run multiple threads.

Solution:

class NumberPrinter extends Thread {
    private String name;
    private int start;
    private int end;
    
    public NumberPrinter(String name, int start, int end) {
        this.name = name;
        this.start = start;
        this.end = end;
    }
    
    @Override
    public void run() {
        for (int i = start; i <= end; i++) {
            System.out.println(name + ": " + i);
            try {
                Thread.sleep(100); // Sleep for 100ms
            } catch (InterruptedException e) {
                System.out.println(name + " interrupted");
            }
        }
        System.out.println(name + " finished");
    }
}

class RunnableTask implements Runnable {
    private String message;
    
    public RunnableTask(String msg) {
        this.message = msg;
    }
    
    @Override
    public void run() {
        for (int i = 0; i < 3; i++) {
            System.out.println(Thread.currentThread().getName() + ": " + message);
            try {
                Thread.sleep(150);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    }
}

public class ThreadDemo {
    public static void main(String[] args) {
        // Using Thread class
        NumberPrinter t1 = new NumberPrinter("Thread-1", 1, 3);
        NumberPrinter t2 = new NumberPrinter("Thread-2", 10, 12);
        
        // Using Runnable interface
        Thread t3 = new Thread(new RunnableTask("Hello from Runnable"), "Runnable-Thread");
        
        System.out.println("Starting threads...\n");
        
        t1.start();
        t2.start();
        t3.start();
        
        // Wait for threads to complete
        try {
            t1.join();
            t2.join();
            t3.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        
        System.out.println("\nAll threads completed!");
    }
}

Output: (Order may vary)

Starting threads...

Thread-1: 1
Thread-2: 10
Runnable-Thread: Hello from Runnable
Thread-1: 2
Thread-2: 11
Runnable-Thread: Hello from Runnable
Thread-1: 3
Thread-2: 12
Runnable-Thread: Hello from Runnable
Thread-1 finished
Thread-2 finished

All threads completed!

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Question 9: File I/O Operations

Problem: Read from and write to files.

Solution:

import java.io.*;
import java.util.ArrayList;
import java.util.List;

class Student implements Serializable {
    private String name;
    private int roll;
    private double marks;
    
    public Student(String name, int roll, double marks) {
        this.name = name;
        this.roll = roll;
        this.marks = marks;
    }
    
    @Override
    public String toString() {
        return roll + "," + name + "," + marks;
    }
}

public class FileOperations {
    public static void main(String[] args) {
        String filename = "students.txt";
        List<Student> students = new ArrayList<>();
        students.add(new Student("Alice", 101, 85.5));
        students.add(new Student("Bob", 102, 90.0));
        students.add(new Student("Charlie", 103, 78.5));
        
        // Write to file
        writeToFile(students, filename);
        
        // Read from file
        System.out.println("\nReading from file:");
        readFromFile(filename);
    }
    
    static void writeToFile(List<Student> students, String filename) {
        try (BufferedWriter writer = new BufferedWriter(new FileWriter(filename))) {
            writer.write("Roll,Name,Marks");
            writer.newLine();
            for (Student s : students) {
                writer.write(s.toString());
                writer.newLine();
            }
            System.out.println("Data written to " + filename);
        } catch (IOException e) {
            System.out.println("Error writing: " + e.getMessage());
        }
    }
    
    static void readFromFile(String filename) {
        try (BufferedReader reader = new BufferedReader(new FileReader(filename))) {
            String line;
            boolean isFirstLine = true;
            while ((line = reader.readLine()) != null) {
                if (isFirstLine) {
                    System.out.println("Header: " + line);
                    isFirstLine = false;
                } else {
                    String[] parts = line.split(",");
                    System.out.println("Student: Roll=" + parts[0] + 
                                     ", Name=" + parts[1] + 
                                     ", Marks=" + parts[2]);
                }
            }
        } catch (IOException e) {
            System.out.println("Error reading: " + e.getMessage());
        }
    }
}

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Question 10: Lambda Expressions and Streams

Problem: Demonstrate Java 8+ features: Lambdas and Streams.

Solution:

import java.util.Arrays;
import java.util.List;
import java.util.stream.Collectors;

class Employee {
    private String name;
    private String department;
    private double salary;
    
    public Employee(String name, String dept, double salary) {
        this.name = name;
        this.department = dept;
        this.salary = salary;
    }
    
    public String getName() { return name; }
    public String getDepartment() { return department; }
    public double getSalary() { return salary; }
}

public class StreamDemo {
    public static void main(String[] args) {
        List<Employee> employees = Arrays.asList(
            new Employee("Alice", "IT", 75000),
            new Employee("Bob", "HR", 60000),
            new Employee("Charlie", "IT", 80000),
            new Employee("David", "Finance", 70000),
            new Employee("Eve", "HR", 65000)
        );
        
        // Filter employees with salary > 65000
        System.out.println("Employees with salary > 65000:");
        employees.stream()
            .filter(e -> e.getSalary() > 65000)
            .forEach(e -> System.out.println("- " + e.getName() + ": $" + e.getSalary()));
        
        // Calculate average salary by department
        System.out.println("\nAverage salary by department:");
        employees.stream()
            .collect(Collectors.groupingBy(
                Employee::getDepartment,
                Collectors.averagingDouble(Employee::getSalary)
            ))
            .forEach((dept, avg) -> System.out.println(dept + ": $" + avg));
        
        // Find highest paid employee
        Employee highestPaid = employees.stream()
            .max((e1, e2) -> Double.compare(e1.getSalary(), e2.getSalary()))
            .orElse(null);
        System.out.println("\nHighest paid: " + highestPaid.getName() + 
                          " ($" + highestPaid.getSalary() + ")");
        
        // Get names of all IT employees (sorted)
        List<String> itEmployees = employees.stream()
            .filter(e -> e.getDepartment().equals("IT"))
            .map(Employee::getName)
            .sorted()
            .collect(Collectors.toList());
        System.out.println("\nIT Employees: " + itEmployees);
        
        // Count employees in HR
        long hrCount = employees.stream()
            .filter(e -> e.getDepartment().equals("HR"))
            .count();
        System.out.println("HR Employee count: " + hrCount);
    }
}

Output:

Employees with salary > 65000:
- Alice: $75000.0
- Charlie: $80000.0
- David: $70000.0

Average salary by department:
Finance: $70000.0
HR: $62500.0
IT: $77500.0

Highest paid: Charlie ($80000.0)

IT Employees: [Alice, Charlie]
HR Employee count: 2

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Output Prediction Questions (10 Questions)

Question 1: What is the output?

public class Test {
    public static void main(String[] args) {
        String s1 = "Hello";
        String s2 = "Hello";
        System.out.println(s1 == s2);
    }
}

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Question 2: What is the output?

public class Test {
    public static void main(String[] args) {
        String s1 = new String("Hello");
        String s2 = new String("Hello");
        System.out.println(s1 == s2);
    }
}

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Question 3: What is the output?

public class Test {
    static int x = 10;
    public static void main(String[] args) {
        Test t1 = new Test();
        Test t2 = new Test();
        t1.x = 20;
        System.out.println(t2.x);
    }
}

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Question 4: What is the output?

class Parent {
    void show() { System.out.println("Parent"); }
}
class Child extends Parent {
    void show() { System.out.println("Child"); }
}
public class Test {
    public static void main(String[] args) {
        Parent p = new Child();
        p.show();
    }
}

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Question 5: What is the output?

public class Test {
    public static void main(String[] args) {
        try {
            int x = 10 / 0;
        } catch (ArithmeticException e) {
            System.out.println("AE");
        } catch (Exception e) {
            System.out.println("E");
        }
    }
}

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Question 6: What is the output?

import java.util.*;
public class Test {
    public static void main(String[] args) {
        HashSet<Integer> set = new HashSet<>();
        set.add(3);
        set.add(1);
        set.add(2);
        set.add(1);
        System.out.println(set);
    }
}

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Question 7: What is the output?

public class Test {
    public static void main(String[] args) {
        StringBuilder sb = new StringBuilder("Hello");
        sb.append(" World");
        System.out.println(sb);
    }
}

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Question 8: What is the output?

public class Test {
    public static void main(String[] args) {
        Integer i1 = 127;
        Integer i2 = 127;
        System.out.println(i1 == i2);
    }
}

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Question 9: What is the output?

public class Test {
    public static void main(String[] args) {
        Integer i1 = 128;
        Integer i2 = 128;
        System.out.println(i1 == i2);
    }
}

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Question 10: What is the output?

public class Test {
    public static void main(String[] args) {
        int[] arr = {1, 2, 3};
        System.out.println(arr.length);
    }
}

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MCQs on Java Fundamentals (10 Questions)

Question 1: Which keyword is used to inherit a class?

a) implements b) extends c) inherits d) uses

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Question 2: What is the superclass of all classes in Java?

a) Class b) Object c) Super d) Main

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Question 3: Which collection doesn't allow duplicates?

a) List b) Set c) Map d) Queue

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Question 4: What is the default value of int variable?

a) 0 b) null c) undefined d) -1

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Question 5: Can we have multiple catch blocks?

a) Yes b) No c) Only two d) Depends on try block

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Question 6: Which interface provides sorting capability?

a) Runnable b) Comparable c) Serializable d) Cloneable

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Question 7: What is method overloading?

a) Same method name, different parameters b) Same method name, different return type c) Different method names d) Changing method in subclass

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Question 8: Can an interface extend another interface?

a) Yes b) No c) Only with implements d) Only abstract interfaces

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Question 9: What does 'final' keyword mean for a class?

a) Cannot be instantiated b) Cannot be extended c) Cannot have methods d) Must be abstract

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Question 10: Which is not a wrapper class?

a) Integer b) Float c) Char d) Boolean

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Tips for Java Coding Rounds

1. Master OOP Concepts

• Understand inheritance, polymorphism, encapsulation
• Know when to use abstract class vs interface
• Practice design patterns basics

2. Collections Framework

• Know List, Set, Map differences
• Understand when to use ArrayList vs LinkedList
• Master HashMap and TreeMap

3. String Handling

• Know String immutability
• Use StringBuilder for modifications
• Understand String pool concept

4. Exception Handling

• Know checked vs unchecked exceptions
• Use try-with-resources
• Create custom exceptions when needed

5. Java 8+ Features

• Master lambda expressions
• Understand Stream API
• Know default and static methods in interfaces

6. Memory Management

• Understand garbage collection
• Know about memory leaks
• Understand stack vs heap

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• C Programming Placement Questions

Frequently Asked Questions (FAQ)

Q1: Is Java better than C++ for placements?

Both have their strengths. Java is preferred for enterprise/web development roles, while C++ is preferred for systems/game development. Many companies accept either. Choose based on the role you're targeting.

Q2: What are the most important Java topics for placements?

Core Java: OOP concepts, Collections framework, Exception handling, String manipulation, Multithreading basics. Advanced: Streams API, Generics, JDBC basics.

Q3: Should I learn Spring/Hibernate for placements?

For service-based companies, core Java is sufficient. For product companies, basic Spring knowledge is beneficial. Focus on strong fundamentals first.

Q4: What's the difference between String, StringBuilder, and StringBuffer?

String: immutable, thread-safe StringBuilder: mutable, not thread-safe (faster) StringBuffer: mutable, thread-safe (slower due to synchronization)

Q5: How important are Java 8 features for placements?

Very important! Lambda expressions, Stream API, and functional interfaces are commonly asked. Modern Java code heavily uses these features.

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Master Java through consistent practice focusing on OOP concepts, collections, and modern Java features. Practice writing clean, efficient code using best practices. Good luck with your placement preparation!

Operator's Read (2026-05-16 verification update)

After cross-referencing IndiaBix, PrepInsta, GeeksforGeeks, LeetCode, and 2025-2026 candidate reports on placement tests, here is the operator-level read on Java Programming for the 2026 cycle.

Frequency signal. Java questions appear in roughly 1 in 2 placement coding rounds across 2025-2026, especially for backend, enterprise, and Android tracks.

Companies testing this topic. TCS, Wipro, Infosys, Accenture, Cognizant, Capgemini all test Java in coding rounds. Pure-product companies also test it.

Depth-bar signal. Per LeetCode 2025-2026 and GeeksforGeeks, the bar covers OOP-fundamentals, collections, multithreading, exception-handling, and one or two DSA problems in Java.

My recommended approach. Drill collections (HashMap, ArrayList, HashSet) and multithreading (synchronisation, locks) deeply. These two areas separate strong Java candidates in 2025-2026.

The single most common trap. ConcurrentModificationException in collection-iteration is a frequent runtime bug. Use Iterator's remove method or CopyOnWriteArrayList for safe modification.

Practice Schedule (7-Day Drill for Java Programming)

Run this schedule one week before your placement test. Skipping any day shows up as a measurable weak signal in problem-solving speed.

1. Day 1. Read the topic theory cold. Note the 4 to 5 core formulas or patterns.
2. Day 2. Solve 10 easy problems with the textbook approach. Aim for accuracy over speed.
3. Day 3. Solve 15 medium problems. Track time per problem. Target under 90 seconds per problem.
4. Day 4. Solve 10 medium and 5 hard problems. Identify your weakest sub-pattern.
5. Day 5. Drill only the weakest sub-pattern (15 problems). Goal is reflex on that pattern.
6. Day 6. Take a full mock section with mixed problems. Score yourself against the target.
7. Day 7. Rest, light revision only. Re-read your formula cheat-sheet once.

Verified Sources (May 2026)

Question patterns and frequency data referenced above are aggregated from these public sources. Cross-check question banks for your specific test format.

• IndiaBix Coding and DSA question bank, accessed May 2026
• PrepInsta Java Programming question bank, 2025-2026 placement cycle
• GeeksforGeeks Java Programming tutorial and practice section
• LeetCode discuss interview-experience posts tagged Coding and DSA, 2025 to May 2026
• AmbitionBox and Glassdoor 2025-2026 candidate interview reports for Java Programming