Which of the following exceptions is a checked exception?

The correct answer is B: FileNotFoundException. FileNotFoundException is a checked exception (extends IOException). Others are unchecked - ClassCastException and NullPointerException are RuntimeExceptions, StackOverflowError is an Error.

What will be the result of: int a = 10; int b = 20; System.out.println(a + b + "Java");?

The correct answer is A: "30Java". When + operator is used with numeric values first, they are added (10 + 20 = 30), and then concatenated with the string "Java", resulting in "30Java".

Which method must be called to move cursor to the next row in ResultSet?

The correct answer is A: next(). The next() method moves the ResultSet cursor to the next row and returns true if a row exists, false if no more rows. It's essential for iterating through results.

Which exception is thrown when attempting to access an index outside the bounds of an array?

The correct answer is B: ArrayIndexOutOfBoundsException. ArrayIndexOutOfBoundsException is thrown when attempting to access array elements with invalid indices. It's an unchecked exception extending RuntimeException.

Consider a method signature: public void readFile() throws IOException. Which statement is correct?

The correct answer is B: This method may throw IOException that caller must handle. throws declaration indicates the method may throw IOException. The caller is responsible for handling it with try-catch or declaring throws. The method doesn't always throw it.

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Java Programming

Java OOP, collections, multithreading

476 Q 10 Topics Take Mock Test

Difficulty: All Easy Medium Hard 431–440 of 476

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.431 Medium Basics & Syntax

Consider a scenario where you need to create a variable that can hold references to objects of any type. Which of the following approaches would be most appropriate in Java 2024 standards?

A Use raw type: List myList = new ArrayList();

B Use generics: List myList = new ArrayList();

C Use Object type: Object obj = new Object();

D Use var keyword: var myList = new ArrayList();

Correct Answer: B. Use generics: List myList = new ArrayList();

EXPLANATION

Using generics with wildcards (List<?>) is the safest and most type-safe approach to handle objects of any type in modern Java. The 'var' keyword is also acceptable but wildcards provide better type checking.

Test

Q.432 Medium Basics & Syntax

What will be the output of the following code?
String str1 = "Hello";
String str2 = new String("Hello");
System.out.println(str1 == str2);

A true

B false

C null

D Compilation error

Correct Answer: B. false

EXPLANATION

The '==' operator compares object references, not content. str1 refers to the string pool while str2 is a new object in heap memory, hence they have different references.

Test

Q.433 Medium Basics & Syntax

Which method is called automatically when an object is garbage collected?

A finalize()

B destroy()

C delete()

D cleanup()

Correct Answer: A. finalize()

EXPLANATION

The finalize() method is called by the garbage collector before an object is destroyed. It can be used to perform cleanup operations, though it's generally not recommended in modern Java.

Test

Q.434 Medium Basics & Syntax

Which of the following will compile and run without errors?

A public static void main() { }

B public static void main(String[] args) { }

C public void main(String[] args) { }

D static void main(String[] args) { }

Correct Answer: B. public static void main(String[] args) { }

EXPLANATION

The correct signature for the main method is 'public static void main(String[] args)'. It must be public, static, void, named 'main', and accept a String array parameter. Any deviation will not be recognized as the entry point.

Test

Q.435 Medium Basics & Syntax

Which of the following correctly represents variable declaration and initialization in Java?

A int x; x = 5.5;

B double y = 10;

C boolean flag = true;

D String name = 123;

Correct Answer: C. boolean flag = true;

EXPLANATION

Option C is correct. Option A causes a compilation error (cannot assign double to int). Option B works but there's implicit conversion. Option D causes a compilation error (cannot assign int to String).

Test

Q.436 Medium Basics & Syntax

Which statement about constructors is INCORRECT?

A Constructors can be overloaded

B Constructors must return a value

C Constructors are called automatically when an object is created

D A class can have multiple constructors

Correct Answer: B. Constructors must return a value

EXPLANATION

Constructors do NOT have a return type, not even void. They automatically initialize objects when created. They can be overloaded and a class can have multiple constructors with different parameters.

Test

Q.437 Medium Basics & Syntax

What is the difference between 'break' and 'continue' in loop statements?

A Both terminate the loop

B break exits the loop; continue skips current iteration

C continue exits the loop; break skips current iteration

D They have the same functionality

Correct Answer: B. break exits the loop; continue skips current iteration

EXPLANATION

'break' immediately exits the loop, while 'continue' skips the remaining statements in the current iteration and jumps to the next iteration.

Test

Q.438 Medium Basics & Syntax

Which access modifier allows a member to be accessible only within the same package?

A public

B private

C protected

D default (no modifier)

Correct Answer: D. default (no modifier)

EXPLANATION

When no access modifier is specified, it's called package-private or default access. Members with default access are accessible only within the same package, not from other packages.

Test

Q.439 Medium Basics & Syntax

What will happen if you try to access an index out of bounds in an array?

A Returns 0

B Returns null

C Throws ArrayIndexOutOfBoundsException

D Compilation error

Correct Answer: C. Throws ArrayIndexOutOfBoundsException

EXPLANATION

Accessing an array index that doesn't exist throws an ArrayIndexOutOfBoundsException at runtime. This is a checked exception that must be handled or declared.

Test

Q.440 Medium Basics & Syntax

Which of the following statements about static methods is correct?

A Static methods can access instance variables directly

B Static methods can be overridden by subclasses

C Static methods can only be called using the class name

D Static methods must have a return type

Correct Answer: C. Static methods can only be called using the class name

EXPLANATION

Static methods belong to the class, not to any instance. They are called using the class name (e.g., ClassName.methodName()). They cannot directly access instance variables and cannot be overridden (though they can be hidden).

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