What is the primary advantage of using PreparedStatement over Statement?

The correct answer is A: Faster execution and SQL injection prevention. PreparedStatement offers faster execution due to precompilation and prevents SQL injection through parameterized queries using placeholders (?).

What will be the output? class Test { int x = 5; { x = 10; } Test() { x = 15; } public static void main(String[] args) { Test t = new Test(); System.out.println(t.x); } }

The correct answer is C: 15. Instance initializer block executes after variable initialization but before constructor. Constructor executes last, setting x = 15.

In Java OOP, which principle ensures that internal details of a class are hidden from the outside world?

The correct answer is C: Encapsulation. Encapsulation is the bundling of data and methods into a single unit (class) while hiding internal implementation details using access modifiers.

Consider: Function curry = x -> y -> x + y; What does curry.apply(5).apply(3) return?

The correct answer is A: 8. This is a curried function. curry.apply(5) returns a function that adds 5. Applying that with 3 gives 5 + 3 = 8.

Which collection would you use if you need to maintain a sorted order of elements and also need O(log n) insertion/deletion time complexity?

The correct answer is C: TreeSet. TreeSet maintains elements in sorted order using a Red-Black tree internally, providing O(log n) for add, remove, and contains operations.

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Java Programming
Basics & Syntax

Java OOP, collections, multithreading

34 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 31–34 of 34

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.31 Easy Basics & Syntax

What will be the output of: boolean flag = true; System.out.println(!flag);

A true

B false

C !true

D Compilation error

Correct Answer: B. false

EXPLANATION

The logical NOT operator (!) inverts the boolean value. !true becomes false.

Test

Q.32 Easy Basics & Syntax

What will be the output of the following code? int x = 5; x += 3; System.out.println(x);

A 3

B 5

C 8

D 53

Correct Answer: C. 8

EXPLANATION

The += operator adds the right operand to the left operand. x += 3 is equivalent to x = x + 3, so 5 + 3 = 8.

Test

Q.33 Easy Basics & Syntax

Which keyword is used to create a constant variable in Java?

A const

B constant

C final

D immutable

Correct Answer: C. final

EXPLANATION

The 'final' keyword is used to declare constants in Java. Once assigned, the value cannot be changed.

Test

Q.34 Easy Basics & Syntax

Which of the following is the correct syntax to declare a variable in Java?

A int x = 10;

B int x: 10;

C x int = 10;

D int: x = 10;

Correct Answer: A. int x = 10;

EXPLANATION

Java uses the syntax 'datatype variableName = value;' for variable declaration.

Test

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Basics & Syntax