1Z0-811 Practice Test 4 — 25 Questions

Question 1

What is the output of the program?

Accepted Answer

4. Option A is correct. The loop iterates from i=0 to i=4. When i equals 2, the continue statement skips the rest of the loop body, so the increment of count is not executed for i=2. For the remaining four iterations (i=0,1,3,4), count is incremented, resulting in a final value of 4. Option B is incorrect because the loop code is syntactically valid and compiles without error. Option C would be correct if a break statement were used instead of continue. Option D is incorrect because the loop runs the full 5 iterations, incrementing count 4 times.

Answer

The loop does not compile.

Answer

5

Answer

2

Question 2

A developer receives a ticket that a batch processing job is running indefinitely. The job reads records from a database and processes them in a loop. The code uses a while(true) loop with a break condition when a sentinel value is encountered. However, due to a data anomaly, the sentinel value is never reached, causing the loop to run forever. The developer needs to fix the loop to prevent infinite execution while still allowing processing of all records until the sentinel is reached. Which approach is most appropriate?

Accepted Answer

Add a counter variable and break after a maximum number of iterations. Option D is correct because adding a counter variable and breaking after a maximum number of iterations provides a safety net against infinite loops while still allowing the loop to process all records until the sentinel is reached under normal conditions. This approach is a common defensive programming technique in Java to handle unexpected data anomalies without altering the core loop logic.

Answer

Use a do-while loop that checks the condition at the end

Answer

Change the loop to a for loop with a fixed range based on the expected number of records

Answer

Throw an exception when the loop runs too long

Question 3

Which of the following scenarios demonstrates the most appropriate use of a continue statement?

Accepted Answer

Skipping the current iteration and moving to the next when a condition is met. Option D is correct because the `continue` statement in Java is specifically designed to skip the remaining code in the current iteration of a loop and proceed directly to the next iteration. This is the most appropriate use case, as it allows you to bypass certain iterations based on a condition without breaking out of the loop entirely.

Answer

Restarting the loop from the beginning

Answer

Implementing fall-through in a switch statement

Answer

Exiting a loop early when a condition is met

Question 4

Which TWO statements are true about the switch statement in Java? (Choose two.)

Accepted Answer

It can be used with char variables.. Options A and C are correct. A: Switch supports char, int, short, byte, String, and enum types, so char is valid. B is false because the break statement is optional; without it, execution falls through to the next case. C is true: the default case is optional. D is false because case labels must be compile-time constant expressions, not runtime expressions. E is false because long variables are not allowed in switch statements.

Answer

The break statement is mandatory at the end of each case.

Answer

Case labels can be runtime expressions.

Answer

It can be used with long variables.

Question 5

Refer to the exhibit. What is the result?

Accepted Answer

ArrayIndexOutOfBoundsException. Option B is correct because the loop condition i <= data.length causes i to become 5 when data.length is 5, but valid indices are 0-4. This results in an ArrayIndexOutOfBoundsException. Option A is wrong because the exception occurs before sum reaches 15. Option C is wrong because sum is not 0. Option D is wrong because the code compiles successfully.

Answer

15

Answer

0

Answer

Compilation fails

Question 6

Which TWO statements about interfaces in Java are true?

Accepted Answer

An interface can extend another interface. Interfaces can extend other interfaces and can have default methods with a body.

Answer

An interface can have instance variables

Answer

An interface can implement another interface

Answer

An interface can have final methods

Question 7

Which access modifier allows a member to be accessed only within the same class?

Accepted Answer

private. Private members are accessible only within the same class.

Answer

static

Answer

public

Answer

default (no modifier)

Answer

protected

Question 8

Refer to the exhibit.

What is the output?

Accepted Answer

Photo. The object is Photo, and print() is overridden, so dynamic binding calls Photo's print method.

Answer

Runtime error

Answer

No output

Answer

Compilation error

Answer

Document

Question 9

A developer creates an interface 'Drawable' with a single abstract method 'draw()'. They then create a class 'Circle' that implements Drawable but forgets to provide the draw() method. Circle is not declared abstract. What will happen when compiling Circle?

Accepted Answer

Compilation fails because Circle must either implement draw() or be declared abstract. A class that implements an interface must provide implementations for all abstract methods, or it must be declared abstract. Without the implementation and without being abstract, the class does not compile.

Answer

Compilation fails because interfaces cannot be implemented without overriding all methods

Answer

Compilation succeeds, a default empty method is generated

Answer

Compilation succeeds but a warning is issued

Question 10

A developer wants to achieve loose coupling between components. Which two practices support loose coupling? (Choose two.)

Accepted Answer

Using interfaces to define contracts. Loose coupling is promoted by coding to interfaces and favoring composition over inheritance, as both reduce dependency on concrete implementations.

Answer

Using inheritance to share implementation

Answer

Using private fields with public getters

Answer

Using static methods extensively

Question 11

A class that does not define any constructor has:

Accepted Answer

A default no-argument constructor. Java automatically provides a default no-arg constructor with the same access as the class.

Answer

A private constructor

Answer

A public constructor with arguments

Answer

It cannot be instantiated

Answer

No constructor

Question 12

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 correct answer is D. 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

Answer

The method is not static

Answer

The class is abstract

Question 13

class Parent { void show() { System.out.print("Parent"); } }
class Child extends Parent { void show() { System.out.print("Child"); } }
public class Test { public static void main(String[] args) { Parent p = new Child(); p.show(); } }

What is the output?

Accepted Answer

Child. Although the reference is Parent, the object is Child, and show() is overridden, so Child's version is called.

Answer

Compilation error

Answer

No output

Answer

Parent

Answer

Runtime error

Question 14

A calculator class has two overloaded methods: add(int a, int b) and add(double a, double b). A call to add(3, 4) will invoke which method?

Accepted Answer

add(int, int). Overloaded method resolution is based on compile-time types. The literal 3 and 4 are ints, so the int version is the most specific match and is called.

Answer

add(double, double)

Answer

Runtime decision based on actual parameters

Answer

Compilation error: ambiguous

Question 15

A company's HR system uses an Employee class with sensitive salary information. The team wants to allow other classes to read the salary but not modify it. Which approach best preserves encapsulation?

Accepted Answer

Provide a public getSalary() getter method and keep salary private. Encapsulation is achieved by keeping fields private and providing public getters. A getter allows read-only access without exposing the internal representation.

Answer

Declare the salary field as public

Answer

Create a private method that returns salary only when called from within the same package

Answer

Provide a public setSalary() setter method and keep salary private

Question 16

A security-sensitive class should not be extended by any other class. Which modifier should be applied to the class declaration?

Accepted Answer

final. The final modifier prevents a class from being subclassed, which is appropriate for security or design reasons.

Answer

abstract

Answer

static

Answer

private

Question 17

A logging utility class keeps track of the number of log entries using a static integer variable. The class is instantiated multiple times in the application. How does the count variable behave?

Accepted Answer

All instances share the same count variable. Static variables are shared among all instances of a class. There is only one copy of the variable, regardless of the number of instances.

Answer

Each instance has its own copy of count

Answer

count is reset each time a new instance is created

Answer

count cannot be accessed from static methods

Question 18

Which three statements about constructors in Java are true? (Choose three.)

Accepted Answer

The default constructor has no parameters. Constructors can be overloaded to provide different initialization options, they cannot return a value (not even void), and if no constructor is defined, the compiler provides a default no-arg constructor.

Answer

Constructors can be abstract

Answer

Constructors can be final

Question 19

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

Answer

Builder pattern with a static inner class

Answer

Factory pattern with a public constructor

Question 20

A junior developer writes a method that attempts to modify a String: public void update() { String s = "Hello"; s.concat(" World"); System.out.println(s); } What will be printed when update() is called?

Accepted Answer

Hello. Strings are immutable in Java. The concat() method returns a new String but the original object remains unchanged because the result is not assigned.

Answer

Hello World

Answer

Hello World (no space)

Answer

Compilation error

1Z0-811 Practice Test 4 — 25 Questions

Exhibit

1Z0-811 Practice Test 4 — 25 Questions

Exhibit