Java Multiple Choice Questions

What is a thread in Java? a) A method in Java b) A class in Java c) A lightweight sub-process d) A data structure

Answer: c) A lightweight sub-process
Which class is used to create a thread in Java? a) Thread b) Runnable c) Process d) Executor

Answer: a) Thread
What is the maximum number of threads that can be created in Java? a) 256 b) 512 c) Unlimited d) Depends on the system

Answer: d) Depends on the system
Which method is used to start a thread in Java? a) run() b) start() c) execute() d) launch()

Answer: b) start()
What is the default priority of a thread in Java? a) MIN_PRIORITY b) MAX_PRIORITY c) NORM_PRIORITY d) DEFAULT_PRIORITY

Answer: c) NORM_PRIORITY

What is the output of the following code?

 class MyThread extends Thread {
     public void run() {
         System.out.println("Hello, World!");
     }
 }

 public class Main {
     public static void main(String[] args) {
         MyThread thread = new MyThread();
         thread.run();
     }
 }

a) Hello, World! b) Compiler error c) Runtime error d) No output

Answer: a) Hello, World!

What is an object in object-oriented programming (OOP)? a) A data type b) A method c) An instance of a class d) A keyword

Answer: c) An instance of a class
What is encapsulation in Java? a) A way to achieve inheritance b) A way to hide implementation details c) A way to create multiple objects d) A way to achieve polymorphism

Answer: b) A way to hide implementation details
Which access modifier allows a class to be accessed from any other class in the same package? a) private b) protected c) public d) default

Answer: d) default
Which keyword is used to inherit a class in Java? a) super b) this c) extends d) implements

Answer: c) extends

What is the output of the following code?

class Base {
    public void print() {
        System.out.println("Base");
    }
}

class Derived extends Base {
    public void print() {
        System.out.println("Derived");
    }
}

public class Main {
    public static void main(String[] args) {
        Base obj = new Derived();
        obj.print();
    }
}

a) Base b) Derived c) Compiler error d) Runtime error

Answer: b) Derived

Which method is used to compare two strings in Java? a) compare() b) equals() c) compareTo() d) equalsIgnoreCase()

Answer: c) compareTo()
What is the output of the following code?
```
String str = "Hello";
str.concat(" World");
System.out.println(str);
```
a) Hello World b) World c) Hello d) Compiler error

Answer: c) Hello
Which method is used to convert a string to uppercase in Java? a) toUpperCase() b) toUpper() c) uppercase() d) upperCase()

Answer: a) toUpperCase()
What is a constructor in Java? a) A method that returns a value b) A method that is used to create objects c) A method that is used to destroy objects d) A method that is used to override superclass methods

Answer: b) A method that is used to create objects
Which keyword is used to refer to the current instance of a class in Java? a) self b) this c) current d) here

Answer: b) this
What is method overloading in Java? a) Defining the same method multiple times with different return types b) Defining the same method multiple times with different parameters c) Defining the same method multiple times in different classes d) Defining a method with the same name as a predefined Java method

Answer: b) Defining the same method multiple times with different parameters
What is the return type of the main() method in Java? a) void b) int c) String d) float

Answer: a) void
What is recursion in Java? a) A process of repeating code multiple times b) A process of defining a method inside another method c) A process of calling a method inside the same method d) A process of executing multiple threads simultaneously

Answer: c) A process of calling a method inside the same method
Which keyword is used to prevent a method from being overridden in Java? a) final b) static c) abstract d) private

Answer: a) final

What is the output of the following code?

class A {
    public void method() {
        System.out.println("A");
    }
}

class B extends A {
    public void method() {
        System.out.println("B");
    }
}

class C extends B {
    public void method() {
        System.out.println("C");
    }
}

public class Main {
    public static void main(String[] args) {
        A obj = new C();
        obj.method();
    }
}

a) A b) B c) C d) Compiler error

Answer: c) C

Which keyword is used to access the superclass methods and variables from a subclass in Java? a) super b) this c) extends d) implements

Answer: a) super
What is the purpose of the static keyword in Java? a) To indicate that a method can be overridden b) To indicate that a variable can be accessed without creating an object c) To indicate that a class cannot be instantiated d) To indicate that a class implements an interface

Answer: b) To indicate that a variable can be accessed without creating an object

What is the output of the following code?

class Test {
    public static void print() {
        System.out.println("Test");
    }
}

public class Main {
    public static void main(String[] args) 
{ 
Test.print();
 } 
}

a) Test b) Compiler error c) Runtime error d) No output

Answer: a) Test

What is a method signature in Java? a) The return type of a method b) The name of a method c) The parameters of a method d) The combination of a method name and parameters

Answer: d) The combination of a method name and parameters

What is the output of the following code?

class Base {
    public void display() {
        System.out.println("Base");
    }
}

class Derived extends Base {
    public void display() {
        super.display();
        System.out.println("Derived");
    }
}

public class Main {
    public static void main(String[] args) {
        Derived obj = new Derived();
        obj.display();
    }
}

a) Base Derived b) Derived Base c) Base d) Derived

Answer: a) Base Derived

What is the purpose of the synchronized keyword in Java? a) To prevent method overloading b) To indicate that a method can be overridden c) To prevent multiple threads from accessing a shared resource simultaneously d) To define a block of code that can be executed by only one thread at a time

Answer: c) To prevent multiple threads from accessing a shared resource simultaneously

What is the output of the following code?

class Base {
    protected int x;

    public Base() {
        x = 5;
    }
}

class Derived extends Base {
    private int x;

    public Derived() {
        x = 10;
    }

    public void display() {
        System.out.println(super.x);
        System.out.println(x);
    }
}

public class Main {
    public static void main(String[] args) {
        Derived obj = new Derived();
        obj.display();
    }
}

a) 5 10 b) 10 10 c) Compiler error d) Runtime error

Answer: a) 5 10

What is the output of the following code?

class Test {
    private int x;

    public Test(int x) {
        this.x = x;
    }

    public int getX() {
        return x;
    }
}

public class Main {
    public static void main(String[] args) {
        Test obj = new Test(5);
        System.out.println(obj.getX());
    }
}

a) 0 b) 5 c) Compiler error d) Runtime error

Answer: b) 5

What is the purpose of the finalize() method in Java? a) To free system resources before an object is garbage collected b) To call the superclass constructor from a subclass c) To prevent a method from being overridden d) To handle exceptions thrown by a method

Answer: a) To free system resources before an object is garbage collected

What is the output of the following code?

class Test {
    public void method1() {
        System.out.println("Method 1");
    }

    public void method2() {
        method1();
    }
}

public class Main {
    public static void main(String[] args){ 
        Test obj = new Test(); 
        obj.method2(); 
    } 
}

a) Method 1 b) Method 2 c) Compiler error d) Runtime error

Answer: a) Method 1

Which keyword is used to handle exceptions in Java? a) try b) catch c) finally d) all of the above

Answer: d) all of the above

What is the output of the following code?

public class Main {
    public static void main(String[] args) {
        System.out.println(Math.sqrt(25));
    }
}

a) 5 b) 25 c) 0 d) Compiler error

Answer: a) 5

What is the purpose of the break statement in Java? a) To exit a loop or switch statement b) To skip the current iteration of a loop c) To continue to the next iteration of a loop d) To return a value from a method

Answer: a) To exit a loop or switch statement

What is the output of the following code?

public class Main {
    public static void main(String[] args) {
        int i = 0;
        while (i < 5) {
            System.out.println(i);
            i++;
        }
    }
}

a) 0 1 2 3 4 b) 5 c) Compiler error d) Runtime error

Answer: a) 0 1 2 3 4

What is the purpose of the continue statement in Java? a) To exit a loop or switch statement b) To skip the current iteration of a loop c) To continue to the next iteration of a loop d) To return a value from a method

Answer: c) To continue to the next iteration of a loop

What is the output of the following code?

public class Main {
    public static void main(String[] args) {
        for (int i = 0; i < 5; i++) {
            if (i == 2) {
                continue;
            }
            System.out.println(i);
        }
    }
}

a) 0 1 3 4 b) 2 c) Compiler error d) Runtime error

Answer: a) 0 1 3 4

What is the purpose of the try-catch-finally block in Java? a) To handle exceptions b) To define a block of code that must be executed regardless of whether an exception is thrown or not c) To define a block of code that is always executed d) All of the above

Answer: d) All of the above

What is the output of the following code?

public class Main {
    public static void main(String[] args) {
        try {
            int result = 10 / 0;
            System.out.println(result);
        } catch (ArithmeticException e) {
            System.out.println("Divide by zero error");
        }
    }
}

a) 10 b) Divide by zero error c) Compiler error d) Runtime error

Answer: b) Divide by zero error

What is the purpose of the throw statement in Java? a) To throw an exception b) To terminate the program c) To define a new class d) To define a new method

Answer: a) To throw an exception

What is the output of the following code?

public class Main {
    public static void main(String[] args) {
        try {
            throw new Exception("Custom Exception");
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }
}

a) Custom Exception b) Exception c) Compiler error d) Runtime error

Answer: a) Custom Exception

What is the purpose of the throws keyword in Java? a) To indicate that a method can throw an exception b) To indicate that a method can be overridden c) To indicate that a class implements an interface d) To indicate that a class cannot be instantiated

Answer: a) To indicate that a method can throw an exception

What is the output of the following code?

public class Main {
    public static void main(String[] args) {
        int[] numbers = {1, 2, 3, 4, 5};
        try {
            System.out.println(numbers[10]);
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("Array index out of bounds");
        }
    }
}

a) 10 b) Array index out of bounds c) Compiler error d) Runtime error

Answer: b) Array index out of bounds

What is the purpose of the finally block in Java? a) To handle exceptions b) To define a block of code that must be executed regardless of whether an exception is thrown or not c) To define a block of code that is always executed d) All of the above

Answer: b) To define a block of code that must be executed regardless of whether an exception is thrown or not

What is the output of the following code?

public class Main {
    public static void main(String[] args) {
        try {
            System.exit(0);
        } finally {
            System.out.println("Finally block");
        }
    }
}

a) Finally block b) Compiler error c) Runtime error d) No output

Answer: d) No output

What is the difference between method overloading and method overriding in Java? a) Method overloading occurs within the same class, while method overriding occurs in different classes b) Method overloading is defined in the superclass, while method overriding is defined in the subclass c) Method overloading involves defining the same method multiple times with different parameters, while method overriding involves defining a method in the subclass with the same name and parameters as a method in the superclass d) Method overloading is a static binding, while method overriding is a dynamic binding

Answer: c) Method overloading involves defining the same method multiple times with different parameters, while method overriding involves defining a method in the subclass with the same name and parameters as a method in the superclass
What is the difference between an instance variable and a local variable in Java? a) Instance variables are declared inside a method, while local variables are declared outside a method b) Instance variables are static, while local variables are non-static c) Instance variables are accessible within the class, while local variables are accessible within the method where they are declared d) Instance variables are initialized with a default value, while local variables must be initialized before they are used

Answer: c) Instance variables are accessible within the class, while local variables are accessible within the method where they are declared
What is the difference between a class variable and an instance variable in Java? a) Class variables are static, while instance variables are non-static b) Class variables are declared inside a method, while instance variables are declared outside a method c) Class variables are shared among all instances of a class, while instance variables have separate copies for each instance d) Class variables are initialized with a default value, while instance variables must be initialized before they are used

Answer: c) Class variables are shared among all instances of a class, while instance variables have separate copies for each instance
What is the difference between the equals() method and the == operator in Java? a) The equals() method is used to compare objects for equality, while the == operator is used to compare primitive types for equality b) The equals() method compares the memory addresses of objects, while the == operator compares the values of objects c) The equals() method is used for reference comparison, while the == operator is used for value comparison d) The equals() method compares the values of objects, while the == operator compares the memory addresses of objects

Answer: a) The equals() method is used to compare objects for equality, while the == operator is used to compare primitive types for equality
What is the difference between the StringBuffer class and the StringBuilder class in Java? a) The StringBuffer class is mutable, while the StringBuilder class is immutable b) The StringBuffer class is synchronized, while the StringBuilder class is not synchronized c) The StringBuffer class is faster than the StringBuilder class d) The StringBuffer class can be used in a multi-threaded environment, while the StringBuilder class cannot

Answer: b) The StringBuffer class is synchronized, while the StringBuilder class is not synchronized
What is the difference between the throw and throws keywords in Java? a) The throw keyword is used to throw an exception, while the throws keyword is used to declare an exception that a method can throw b) The throw keyword is used in a try-catch block, while the throws keyword is used in a method signature c) The throw keyword is used for checked exceptions, while the throws keyword is used for unchecked exceptions d) The throw keyword is used in a catch block, while the throws keyword is used in a try block

Answer: a) The throw keyword is used to throw an exception, while the throws keyword is used to declare an exception that a method can throw
What is the difference between checked exceptions and unchecked exceptions in Java? a) Checked exceptions are checked at compile-time, while unchecked exceptions are checked at runtime b) Checked exceptions must be caught or declared, while unchecked exceptions do not need to be caught or declared c) Checked exceptions are subclasses of RuntimeException, while unchecked exceptions are subclasses of Exception d) Checked exceptions are caused by programming errors, while unchecked exceptions are caused by external factors

Answer: b) Checked exceptions must be caught or declared, while unchecked exceptions do not need to be caught or declared
What is method chaining in Java? a) Calling multiple methods on the same object in a single line of code b) Calling methods with the same name but different parameters c) Calling methods of different classes in a sequential manner d) Calling methods with a return type of void

Answer: a) Calling multiple methods on the same object in a single line of code
What is polymorphism in Java? a) The ability of a subclass to inherit fields and methods from a superclass b) The ability to define multiple methods with the same name but different parameters in a class c) The ability of an object to take on many forms and be treated as an instance of its own class or its superclass d) The ability to define a method in multiple classes with the same name but different implementations

Answer: c) The ability of an object to take on many forms and be treated as an instance of its own class or its superclass
What is method overriding in Java? a) Defining a method with the same name but different parameters in a subclass b) Defining a method in a subclass with the same name and parameters as a method in the superclass c) Calling a method in a superclass from a subclass d) Hiding a method in the superclass with a method in the subclass

Answer: b) Defining a method in a subclass with the same name and parameters as a method in the superclass
What is method overloading in Java? a) Defining a method with the same name but different parameters in a subclass b) Defining a method in a subclass with the same name and parameters as a method in the superclass c) Calling a method in a superclass from a subclass d) Hiding a method in the superclass with a method in the subclass

Answer: a) Defining a method with the same name but different parameters in a subclass
What is the final keyword used for in Java? a) To indicate that a class cannot be subclassed b) To indicate that a method cannot be overridden in a subclass c) To indicate that a variable cannot be reassigned once it is initialized d) All of the above

Answer: d) All of the above
What is the static keyword used for in Java? a) To indicate that a variable is an instance variable b) To indicate that a method can be overridden c) To indicate that a variable or method belongs to the class rather than an instance of the class d) To indicate that a class is an interface

Answer: c) To indicate that a variable or method belongs to the class rather than an instance of the class
What is the purpose of the this keyword in Java? a) To refer to the current class instance b) To refer to the superclass instance c) To refer to a static variable or method d) To refer to a local variable

Answer: a) To refer to the current class instance
What is the purpose of the super keyword in Java? a) To refer to the current class instance b) To refer to the superclass instance c) To refer to a static variable or method d) To refer to a local variable

Answer: b) To refer to the superclass instance
What is encapsulation in Java? a) The process of combining data and methods into a single unit called a class b) The process of hiding the internal implementation details of a class and providing access to the class through public methods c) The process of creating multiple instances of a class d) The process of defining methods with the same name but different parameters

Answer: b) The process of hiding the internal implementation details of a class and providing access to the class through public methods
What is inheritance in Java? a) The process of combining data and methods into a single unit called a class b) The process of hiding the internal implementation details of a class and providing access to the class through public methods c) The process of creating multiple instances of a class d) The process of one class acquiring the properties and methods of another class

Answer: d) The process of one class acquiring the properties and methods of another class
What is abstraction in Java? a) The process of combining data and methods into a single unit called a class b) The process of hiding the internal implementation details of a class and providing access to the class through public methods c) The process of creating multiple instances of a class d) The process of defining methods with the same name but different parameters

Answer: b) The process of hiding the internal implementation details of a class and providing access to the class through public methods
What is a constructor in Java? a) A method that is used to initialize an object of a class b) A method that is used to define the behavior of a class c) A method that is used to define the properties of a class d) A method that is used to define the superclass of a class

Answer: a) A method that is used to initialize an object of a class
Can a constructor be inherited in Java? a) Yes, a constructor can be inherited b) No, a constructor cannot be inherited c) Only the default constructor can be inherited d) Constructors are not inherited, but they can be overridden

Answer: b) No, a constructor cannot be inherited
What is method hiding in Java? a) The process of defining a method in a subclass with the same name and parameters as a method in the superclass b) The process of defining a method with the same name but different parameters in a subclass c) The process of calling a method in a superclass from a subclass d) The process of overriding a method in the superclass with a method in the subclass

Answer: a) The process of defining a method in a subclass with the same name and parameters as a method in the superclass
Can a subclass override a private method of its superclass? a) Yes, a subclass can override a private method b) No, a subclass cannot override a private method c) Only if the private method is marked with the "final" keyword d) Only if the private method is marked with the "abstract" keyword

Answer: b) No, a subclass cannot override a private method
What is the difference between method overriding and method hiding in Java? a) Method overriding occurs within the same class, while method hiding occurs in different classes b) Method overriding is defined in the superclass, while method hiding is defined in the subclass c) Method overriding involves defining the same method multiple times with different parameters, while method hiding involves defining a method in the subclass with the same name and parameters as a method in the superclass d) Method overriding is a dynamic binding, while method hiding is a static binding

Answer: d) Method overriding is a dynamic binding, while method hiding is a static binding
Can a class be both abstract and final in Java? a) Yes, a class can be both abstract and final b) No, a class cannot be both abstract and final c) Only if the class has no abstract methods d) Only if the class is marked with the "static" keyword

Answer: b) No, a class cannot be both abstract and final
Can an abstract class have a constructor in Java? a) Yes, an abstract class can have a constructor b) No, an abstract class cannot have a constructor c) Only if the constructor is marked with the "abstract" keyword d) Only if the constructor is marked with the "final" keyword

Answer: a) Yes, an abstract class can have a constructor
Can an abstract class be instantiated in Java? a) Yes, an abstract class can be instantiated b) No, an abstract class cannot be instantiated c) Only if all the methods in the abstract class are marked with the "abstract" keyword d) Only if the abstract class is marked with the "final" keyword

Answer: b) No, an abstract class cannot be instantiated
Can an interface have instance variables in Java? a) Yes, an interface can have instance variables b) No, an interface cannot have instance variables c) Only if the instance variables are marked with the "final" keyword d) Only if the interface is marked with the "abstract" keyword

Answer: b) No, an interface cannot have instance variables
Can an interface have constructors in Java? a) Yes, an interface can have constructors b) No, an interface cannot have constructors c) Only if the constructors are marked with the "abstract" keyword d) Only if the interface is marked with the "final" keyword

Answer: b) No, an interface cannot have constructors
Can a class implement multiple interfaces in Java? a) Yes, a class can implement multiple interfaces b) No, a class can implement only one interface c) Only if the interfaces have the same method signatures d) Only if the interfaces have the same instance variables

Answer: a) Yes, a class can implement multiple interfaces
What is the purpose of the default keyword in Java interfaces? a) To indicate that a method can have a default implementation in the interface b) To indicate that a method is accessible only within the interface c) To indicate that a method is accessible only within the class that implements the interface d) To indicate that a method is final and cannot be overridden

Answer: a) To indicate that a method can have a default implementation in the interface
Can an interface extend another interface in Java? a) Yes, an interface can extend another interface b) No, an interface cannot extend another interface c) Only if the interfaces have the same method signatures d) Only if the interfaces have the same instance variables

Answer: a) Yes, an interface can extend another interface
What is the difference between composition and inheritance in Java? a) Composition allows classes to acquire properties and methods from other classes, while inheritance allows classes to be combined into a single unit b) Composition allows classes to be combined into a single unit, while inheritance allows classes to acquire properties and methods from other classes c) Composition is a form of runtime polymorphism, while inheritance is a form of compile-time polymorphism d) Composition is a way to achieve code reusability, while inheritance is a way to achieve code modularity

Answer: b) Composition allows classes to be combined into a single unit, while inheritance allows classes to acquire properties and methods from other classes
What is the difference between aggregation and composition in Java? a) Aggregation is a weak form of composition, while composition is a strong form of aggregation b) Aggregation allows classes to acquire properties and methods from other classes, while composition allows classes to be combined into a single unit c) Aggregation is a form of runtime polymorphism, while composition is a form of compile-time polymorphism d) Aggregation is a way to achieve code reusability, while composition is a way to achieve code modularity

Answer: a) Aggregation is a weak form of composition, while composition is a strong form of aggregation
What is the difference between method overloading and method overriding in Java? a) Method overloading occurs within the same class, while method overriding occurs in different classes b) Method overloading involves defining the same method multiple times with different parameters, while method overriding involves defining a method in a subclass with the same name and parameters as a method in the superclass c) Method overloading is a static binding, while method overriding is a dynamic binding d) Method overloading is used to achieve polymorphism, while method overriding is used to achieve code reuse

Answer: b) Method overloading involves defining the same method multiple times with different parameters, while method overriding involves defining a method in a subclass with the same name and parameters as a method in the superclass
What is the purpose of the final keyword in Java? a) To indicate that a class cannot be subclassed b) To indicate that a method cannot be overridden c) To indicate that a variable or reference cannot be changed once it is assigned d) All of the above

Answer: d) All of the above
What is the purpose of the static keyword in Java? a) To indicate that a variable is an instance variable b) To indicate that a method can be overridden c) To indicate that a variable or method belongs to the class rather than an instance of the class d) To indicate that a class is an interface

Answer: c) To indicate that a variable or method belongs to the class rather than an instance of the class
What is the difference between the final and abstract keywords in Java? a) The final keyword is used to mark a class as abstract, while the abstract keyword is used to mark a class as final b) The final keyword is used to prevent a class from being subclassed or a method from being overridden, while the abstract keyword is used to indicate that a class or method has no implementation and must be overridden c) The final keyword is used to indicate that a class or method has no implementation and must be overridden, while the abstract keyword is used to prevent a class from being subclassed or a method from being overridden d) The final keyword is used to mark a class as static, while the abstract keyword is used to mark a class as dynamic

Answer: b) The final keyword is used to prevent a class from being subclassed or a method from being overridden, while the abstract keyword is used to indicate that a class or method has no implementation and must be overridden
What is the purpose of the synchronized keyword in Java? a) To indicate that a variable or method can be accessed by multiple threads simultaneously b) To indicate that a variable or method cannot be accessed by multiple threads simultaneously c) To indicate that a variable or method is thread-safe d) To indicate that a variable or method is volatile

Answer: c) To indicate that a variable or method is thread-safe
What is the purpose of the transient keyword in Java? a) To indicate that a variable or method can be accessed by multiple threads simultaneously b) To indicate that a variable or method cannot be accessed by multiple threads simultaneously c) To indicate that a variable or method is thread-safe d) To indicate that a variable should not be serialized during object serialization

Answer: d) To indicate that a variable should not be serialized during object serialization
What is the purpose of the volatile keyword in Java? a) To indicate that a variable or method can be accessed by multiple threads simultaneously b) To indicate that a variable or method cannot be accessed by multiple threads simultaneously c) To indicate that a variable or method is thread-safe d) To indicate that a variable's value may be modified by different threads

Answer: d) To indicate that a variable's value may be modified by different threads
What is the difference between a shallow copy and a deep copy in Java? a) A shallow copy creates a new object with the same references as the original object, while a deep copy creates a new object with new copies of the referenced objects b) A shallow copy creates a new object with new copies of the referenced objects, while a deep copy creates a new object with the same references as the original object c) A shallow copy is performed using the clone() method, while a deep copy is performed using the copy() method d) A shallow copy copies the contents of the object, while a deep copy copies the object itself

Answer: a) A shallow copy creates a new object with the same references as the original object, while a deep copy creates a new object with new copies of the referenced objects
What is the purpose of the equals() method in Java? a) To compare the memory addresses of two objects b) To compare the values of two objects for equality c) To compare the references of two objects d) To compare the sizes of two objects

Answer: b) To compare the values of two objects for equality
What is the purpose of the hashCode() method in Java? a) To return the memory address of an object b) To return a unique identifier for an object c) To compare the memory addresses of two objects d) To compare the sizes of two objects

Answer: b) To return a unique identifier for an object
What is the purpose of the toString() method in Java? a) To return the memory address of an object b) To return a unique identifier for an object c) To return a string representation of an object d) To compare the sizes of two objects

Answer: c) To return a string representation of an object
What is the purpose of the finalize() method in Java? a) To return the memory address of an object b) To release system resources held by an object before it is garbage collected c) To compare the memory addresses of two objects d) To compare the sizes of two objects

Answer: b) To release system resources held by an object before it is garbage collected
What is the difference between the == operator and the equals() method in Java? a) The == operator compares the memory addresses of two objects, while the equals() method compares the values of two objects for equality b) The == operator compares the values of two objects for equality, while the equals() method compares the memory addresses of two objects c) The == operator is used to assign values to variables, while the equals() method is used to compare the values of two variables d) The == operator is used to compare primitive data types, while the equals() method is used to compare objects

Answer: a) The == operator compares the memory addresses of two objects, while the equals() method compares the values of two objects for equality
What is the purpose of the super keyword in Java? a) To call the superclass constructor b) To call the subclass constructor c) To access the superclass's instance variables and methods d) To access the subclass's instance variables and methods

Answer: c) To access the superclass's instance variables and methods
What is the difference between checked exceptions and unchecked exceptions in Java? a) Checked exceptions are checked at compile-time, while unchecked exceptions are checked at runtime b) Checked exceptions are explicitly declared in the method signature or caught in a try-catch block, while unchecked exceptions are not explicitly declared or caught c) Checked exceptions must be handled or declared, while unchecked exceptions can be handled or ignored d) Checked exceptions are always fatal, while unchecked exceptions are non-fatal

Answer: b) Checked exceptions are explicitly declared in the method signature or caught in a try-catch block, while unchecked exceptions are not explicitly declared or caught
What is the purpose of the throws keyword in Java? a) To declare that a method may throw an exception b) To declare that a method must throw an exception c) To catch an exception and handle it gracefully d) To indicate that a method is not allowed to throw any exceptions

Answer: a) To declare that a method may throw an exception
What is the purpose of the try-catch-finally block in Java? a) To handle checked exceptions b) To handle unchecked exceptions c) To specify code that may throw exceptions and provide a mechanism for handling those exceptions d) To specify code that should always be executed, regardless of whether an exception occurs or not

Answer: c) To specify code that may throw exceptions and provide a mechanism for handling those exceptions
What is the difference between the throw and throws keywords in Java? a) The throw keyword is used to throw an exception, while the throws keyword is used to declare that a method may throw an exception b) The throw keyword is used to catch an exception, while the throws keyword is used to handle an exception c) The throw keyword is used to handle checked exceptions, while the throws keyword is used to handle unchecked exceptions d) The throw keyword is used to handle runtime exceptions, while the throws keyword is used to handle compile-time exceptions

Answer: a) The throw keyword is used to throw an exception, while the throws keyword is used to declare that a method may throw an exception
What is the purpose of the finally block in Java exception handling? a) To specify code that should always be executed, regardless of whether an exception occurs or not b) To catch and handle exceptions c) To declare that a method may throw an exception d) To throw an exception

Answer: a) To specify code that should always be executed, regardless of whether an exception occurs or not
What is the difference between a checked exception and an error in Java? a) Checked exceptions are checked at compile-time, while errors are checked at runtime b) Checked exceptions are caused by programming errors, while errors are caused by environmental conditions or system failures c) Checked exceptions must be explicitly caught or declared, while errors do not need to be caught or declared d) Checked exceptions are fatal, while errors are non-fatal

Answer: b) Checked exceptions are caused by programming errors, while errors are caused by environmental conditions or system failures
What is the purpose of the this keyword in Java? a) To access the superclass's instance variables and methods b) To access the subclass's instance variables and methods c) To refer to the current object within a class's instance method d) To refer to the current class within a static method

Answer: c) To refer to the current object within a class's instance method
What is the purpose of the package keyword in Java? a) To indicate that a class belongs to a specific package b) To indicate that a class is an abstract class c) To indicate that a class is a final class d) To indicate that a class is an interface

Answer: a) To indicate that a class belongs to a specific package

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Java Multiple Choice Questions