What does the PreparedStatement interface provide that Statement does not?

The correct answer is D: Both B and C. PreparedStatement provides both parameterized queries (preventing SQL injection) and precompilation of SQL statements, resulting in better security and performance compared to Statement.

Which wildcard usage follows the Producer pattern?

The correct answer is B: List. Producer (Get-Only pattern) uses upper-bounded wildcard (? extends T). It's used when you want to read/produce elements of specific types.

What is the output of the following code? public class ExceptionTest { public static void main(String[] args) { try { int x = 10 / 0; } catch (ArithmeticException e) { System.out.println("Caught"); } finally { System.out.println("Finally"); } } }

The correct answer is A: Caught Finally. ArithmeticException is caught by the catch block printing 'Caught', then finally block executes printing 'Finally'.

Which of the following lambda expressions is syntactically incorrect?

The correct answer is C: (x, y,) -> x + y. The syntax (x, y,) is incorrect because there's a trailing comma after y. The correct syntax would be (x, y) -> x + y.

What is the output of multiple catch blocks? try { int[] arr = {1, 2, 3}; System.out.println(arr[5]); } catch(ArrayIndexOutOfBoundsException e) { System.out.println("Index"); } catch(Exception e) { System.out.println("Exception"); }

The correct answer is A: Index. ArrayIndexOutOfBoundsException is thrown and caught by the first catch block. The second catch block is not executed. Only the most specific matching catch block executes.

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Java Programming
Basics & Syntax

Java OOP, collections, multithreading

50 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 21–30 of 50

Topics in Java Programming

All Basics & Syntax 100 OOP in Java 100 Collections Framework 100 Multithreading 100 Exception Handling 100 I/O Streams 100 JDBC 100 Generics 100 Lambda Expressions 100 Spring Framework Basics 58

Q.21 Medium Basics & Syntax

What is the output of: System.out.println(true && false || true);

A true

B false

C null

D Compilation Error

Correct Answer: A. true

EXPLANATION

Evaluation: (true && false) || true = false || true = true. AND operator (&& has higher precedence than OR (||).

Test

Q.22 Medium Basics & Syntax

Which of the following will result in a compilation error? class Test { public void method1() { } public void method1(int x) { } }

A Method overloading

B Method overriding

C No error, valid code

D Syntax error

Correct Answer: C. No error, valid code

EXPLANATION

This is valid method overloading. Two methods with same name but different parameters (method signature) is allowed in Java.

Test

Q.23 Medium Basics & Syntax

What is the scope of a variable declared inside a method in Java?

A Global

B Local

C Static

D Package-level

Correct Answer: B. Local

EXPLANATION

Variables declared inside a method have local scope and are only accessible within that method. They are destroyed when the method returns.

Test

Q.24 Medium Basics & Syntax

Consider: class A { static int x = 5; } How many times is x initialized when you create multiple A objects?

A Once per object creation

B Once when the class is loaded

C Multiple times depending on object count

D Twice (once for class, once for object)

Correct Answer: B. Once when the class is loaded

EXPLANATION

Static variables are initialized only once when the class is first loaded into memory, regardless of object creation.

Test

Q.25 Medium Basics & Syntax

Which of the following cannot be inherited in Java?

A Public methods

B Protected methods

C Private methods

D Static methods can be inherited

Correct Answer: C. Private methods

EXPLANATION

Private members are not inherited. They remain accessible only within the class they are declared in.

Test

Q.26 Medium Basics & Syntax

Which of the following about static variables is incorrect?

A Static variables are shared among all instances

B Static variables are initialized when class loads

C Each object has its own copy of static variables

D Static variables can be accessed using class name

Correct Answer: C. Each object has its own copy of static variables

EXPLANATION

Static variables are shared among ALL instances of a class, not individual copies per object.

Test

Q.27 Medium Basics & Syntax

What is the output of: System.out.println(5 % 2 + 3 * 2 - 1);?

A 6

B 7

C 8

D 10

Correct Answer: A. 6

EXPLANATION

Following operator precedence: 5%2=1, 3*2=6, then 1+6-1=6

Test

Q.28 Medium Basics & Syntax

Which statement about constructor overloading is true?

A Constructors cannot be overloaded

B Constructors can be overloaded with different parameter types and counts

C Only one constructor is allowed per class

D Constructor return type must differ for overloading

Correct Answer: B. Constructors can be overloaded with different parameter types and counts

EXPLANATION

Constructors can be overloaded based on parameter count and types, but not on return type.

Test

Q.29 Medium Basics & Syntax

Which access modifier allows access within the same package and subclasses?

A public

B private

C protected

D default

Correct Answer: C. protected

EXPLANATION

protected allows access within the same package and to subclasses even outside the package.

Test

Q.30 Medium Basics & Syntax

What is the difference between == and .equals() for String comparison?

A Both check string content

B == checks reference, .equals() checks content

C == checks content, .equals() checks reference

D They are identical in functionality

Correct Answer: B. == checks reference, .equals() checks content

EXPLANATION

== compares object references (memory location), while .equals() compares the actual string content.

Test

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