1. What is Java, and why is it platform-independent?

Java is a high-level, object-oriented programming language developed by Sun Microsystems. It is platform-independent because Java programs are compiled into bytecode, which can run on any system with a Java Virtual Machine (JVM) 

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2. Explain the difference between JDK, JRE, and JVM.

• JDK (Java Development Kit): A toolkit for developing Java applications, including the compiler and debugger.
• JRE (Java Runtime Environment): Provides the runtime environment to execute Java programs.
• JVM (Java Virtual Machine): Converts bytecode into machine code and executes it
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3. What is the “this” keyword in Java, and how is it used?

The “this” keyword refers to the current object of a class. It is used to:

• Resolve naming conflicts between instance variables and parameters.
• Invoke constructors within the same class.
• Pass the current object as a parameter
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Example:

class Employee {
    private String name;

    Employee(String name) {
        this.name = name; // Resolves conflict between instance variable and parameter
    }

    void display() {
        System.out.println("Employee Name: " + this.name);
    }
}

4. What is the difference between “this” and “super” in Java?

• “this”: Refers to the current object of the class.
• “super”: Refers to the immediate parent class object and is used to access parent class methods, variables, or constructors
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5. Can you explain constructor chaining using the “this” keyword?

Constructor chaining occurs when one constructor calls another constructor within the same class using the “this” keyword.Example:

class Student {
    String name;
    int age;

    Student() {
        this("Unknown", 0); // Calls the parameterized constructor
    }

    Student(String name, int age) {
        this.name = name;
        this.age = age;
    }
}

6. What is the difference between “==” and .equals() in Java?

• “==”: Compares memory addresses (reference comparison).
• .equals(): Compares the content of objects (value comparison)
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7. How does Java handle memory management?

Java uses automatic garbage collection to manage memory. The JVM automatically removes objects that are no longer referenced, freeing up memory 

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8. What is the purpose of the final keyword in Java?

The final keyword is used to:

• Declare constants (final variables).
• Prevent method overriding (final methods).
• Prevent inheritance (final classes)
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9. What are the differences between ArrayList and LinkedList in Java?

• ArrayList: Uses a dynamic array, faster for random access.
• LinkedList: Uses a doubly linked list, faster for insertions and deletions
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10. What is the significance of the synchronized keyword in Java?

The synchronized keyword ensures thread safety by allowing only one thread to access a block of code or method at a time 

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Deep Dive into the “this” Keyword

1. Resolving Naming Conflicts

When a method parameter has the same name as an instance variable, the “this” keyword resolves the ambiguity.Example:

class Car {
    private String model;

    Car(String model) {
        this.model = model; // Resolves conflict
    }
}

2. Invoking Constructors

The “this” keyword can be used to call another constructor within the same class.Example:

class Book {
    String title;
    double price;

    Book() {
        this("Unknown", 0.0); // Calls parameterized constructor
    }

    Book(String title, double price) {
        this.title = title;
        this.price = price;
    }
}

3. Passing the Current Object

The “this” keyword can pass the current object as a parameter to another method or constructor.Example:

class Person {
    void greet(Person p) {
        System.out.println("Hello, " + p);
    }

    void sayHello() {
        greet(this); // Passes the current object
    }
}

4. Returning the Current Object

The “this” keyword can return the current object from a method.Example:

class Builder {
    Builder build() {
        return this; // Returns the current object
    }
}

5. Accessing Instance Methods

The “this” keyword can call instance methods of the current object.Example:

class Calculator {
    void add(int a, int b) {
        System.out.println("Sum: " + (a + b));
    }

    void calculate() {
        this.add(5, 10); // Calls the add method
    }
}

Why Mastering the “this” Keyword is Crucial for Interviews

Understanding the “this” keyword demonstrates your grasp of object-oriented programming principles, such as encapsulation and constructor chaining. It also showcases your ability to write clean, maintainable code.

Conclusion

The “this” keyword is a cornerstone of Java programming, and mastering it can significantly boost your confidence during interviews. By understanding its various applications, you can tackle a wide range of questions and demonstrate your expertise in object-oriented programming.