1Z0-811 Practice Test 5 — 10 Questions

Question 1

Refer to the exhibit. Which statement is true about the InvalidInputException class?

Accepted Answer

It is a checked exception.. The InvalidInputException class extends Exception, which makes it a checked exception. Checked exceptions must be either caught or declared in the method signature using 'throws', otherwise the code will not compile. This is the core reason why option B is correct.

Answer

It cannot be thrown by a method.

Answer

It is an unchecked exception.

Answer

It can only be caught in a finally block.

Question 2

Which THREE statements are true about passing arrays to methods in Java?

Accepted Answer

Varargs parameters allow passing zero or more arguments of the specified type.. Varargs (variable-length arguments) in Java allow a method to accept zero or more arguments of a specified type, using the syntax `Type... param`. This is syntactic sugar for an array parameter, and the method body treats it as an array. This enables flexible method invocation without requiring the caller to explicitly create an array.

Answer

If the method modifies elements of the array, the caller does not see the changes.

Answer

If the method assigns a new array to the parameter, the caller's variable is updated.

Question 3

Which THREE are valid ways to declare and initialize an integer variable in Java? (Choose three.)

Accepted Answer

int x = 1_000;. Java allows underscores in numeric literals (introduced in Java 7) to improve readability, and `1_000` is a valid integer literal representing 1000. The compiler simply ignores the underscores during parsing.

Answer

int x = 2.0;

Answer

int x = 0xG;

Question 4

Which design principle is violated by making all fields public in a class?

Accepted Answer

Encapsulation. Making all fields public violates the principle of encapsulation, which requires that an object's internal state be hidden from external access and only modifiable through controlled methods (getters/setters). In Java, public fields allow any class to directly read or modify the field, breaking data integrity and the ability to enforce invariants. Encapsulation is a core OOP concept that protects the internal representation of an object.

Answer

Inheritance

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Abstraction

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Polymorphism

Question 5

A Java class named 'Helper' is defined in package 'utils'. Another class in a different package tries to access a public method of Helper but receives a compilation error. The Helper class is declared as 'class Helper' (without public modifier). What is the likely issue?

Accepted Answer

The class has package-private access. The Helper class is declared with default (package-private) access because no access modifier is specified. Therefore, it is only accessible within the utils package. A class in a different package cannot access it, even if it tries to call a public method of that class, because the class itself is not accessible. The method's access modifier is irrelevant if the class is not accessible. Option A is incorrect because final does not affect access. Option B is incorrect because static is unrelated to access across packages. Option C is incorrect because abstract does not restrict access.

Answer

The method is declared as final

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The method is not static

Answer

The class is abstract

Question 6

What is the output of this program?

Accepted Answer

30
Sum: 1020. The code compiles and runs without error. The first line prints 30 because the loop variable 'i' ends up as 30 due to a bug in the loop logic. The second line prints 'Sum: 1020' because the variable 'sum' holds the value 10 (the loop only sums certain values incorrectly), and the expression 'Sum: ' + sum + '20' concatenates the string 'Sum: ', the integer 10, and the string '20' to produce 'Sum: 1020'. Therefore, option C is correct.

Answer

Runtime exception

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Compilation error

Answer

30
Sum: 30

Question 7

A developer writes a method that accepts a variable number of int arguments and returns their product. Which method signature correctly implements this?

Accepted Answer

public static int product(int... nums). The syntax `int... nums` is the proper Java varargs syntax, allowing a method to accept zero or more `int` arguments, which are then treated as an array inside the method. This enables the developer to call `product(2, 3, 4)` or `product()` and compute the product by iterating over the array.

Answer

public static int product(int[] nums)

Answer

public static int product(int nums...)

Answer

public static int product(int... nums, int extra)

Question 8

A company is developing a configuration manager that must be shared across all components to ensure consistent settings. The manager should prevent direct instantiation and provide a single access point. Which design pattern and implementation should be used?

Accepted Answer

Singleton pattern with a private constructor and a static getInstance() method. The Singleton pattern ensures a class has only one instance and provides a global point of access. A private constructor prevents direct instantiation, and a static getInstance() method provides controlled access.

Answer

Prototype pattern with cloning

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Builder pattern with a static inner class

Answer

Factory pattern with a public constructor

Question 9

Given two String objects s1 = "Hello" and s2 = "Hello", what does the expression (s1 == s2) return?

Accepted Answer

true. The `==` operator compares object references, not string content. Since both `s1` and `s2` are string literals, Java's string interning ensures they refer to the same `String` object in the string constant pool, so `s1 == s2` returns `true`.

Answer

Compilation error

Answer

false

Answer

It depends on the JVM

Question 10

Which two statements about the break statement in Java are true?

Accepted Answer

break can be used inside a switch case. The break statement is used inside a switch case to terminate the switch block and prevent fall-through to subsequent cases. Without break, execution would continue into the next case, which is often unintended.

Answer

break can be used without any enclosing loop

Answer

break is used to skip to next iteration

Answer

break exits the current loop iteration