1Z0-811 Practice Test 2 — 30 Questions

Question 1

A class has a method that is marked as protected. Which statement is true about its accessibility?

Accepted Answer

Within the same package and subclasses. In Java, the protected access modifier allows access within the same package and by subclasses (even if they are in different packages). Option E correctly states this combination, which is the precise definition of protected access as specified in the Java Language Specification (JLS §6.6.2).

Answer

Only in subclasses

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Only within the same package

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Everywhere

Answer

Only within the same class

Question 2

Given: abstract class Shape { abstract void draw(); } class Circle extends Shape { void draw() {} } Which is true?

Accepted Answer

Circle must override draw(). Circle is a concrete class that extends the abstract class Shape, which declares the abstract method draw(). A concrete subclass of an abstract class must provide an implementation for all inherited abstract methods, unless the subclass is also declared abstract. Circle provides an implementation of draw() with an empty body, which satisfies the override requirement.

Answer

Shape cannot have a constructor

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Shape s = new Shape(); is valid

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draw() must be public in Circle

Question 3

What is the value of the expression (10 > 5) && (3 < 2)?

Accepted Answer

false. The expression (10 > 5) evaluates to true, and (3 < 2) evaluates to false. The logical AND operator (&&) returns true only if both operands are true. Since one operand is false, the entire expression evaluates to false. In Java, the result of a boolean expression is a boolean literal, not an integer.

Answer

1

Answer

true

Answer

0

Question 4

Which three of the following are valid ways to declare and initialize a variable of type int? (Choose three.)

Accepted Answer

int b = 0xA;. `0xA` is a hexadecimal integer literal in Java, representing the decimal value 10. Java allows hexadecimal literals using the prefix `0x` or `0X`, and they are valid for initializing an `int` variable.

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int e = 10.0;

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int c = 0b2;

Question 5

Which two statements about the Arrays class are true? (Choose two.)

Accepted Answer

The Arrays class provides a method to fill an array with a specific value.. The `Arrays.fill()` method allows you to assign a specific value to every element of an array, or to a specified range within the array. This is a static utility method provided by the `java.util.Arrays` class, and it works for both primitive and object arrays.

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The Arrays class provides a method to sort only arrays of primitive types.

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The Arrays class provides a method to perform binary search on any array.

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The Arrays class provides a method to deep copy an array.

Question 6

A method is expected to receive an integer and return its square. Which method signature is correct?

Accepted Answer

int square(int x) { return x*x; }. The method signature specifies a return type of 'int' and includes the 'return' keyword to return the squared value. In Java, a method that returns a value must declare the return type before the method name and must use the 'return' statement to send the result back to the caller.

Answer

void square(int x) { return x*x; }

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public square(int x) { return x*x; }

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int square(int x) { x*x; }

Question 7

Refer to the exhibit.

What is the likely cause?

Accepted Answer

The variable 'value' is not declared. The error message indicates that the variable 'value' has not been declared before use. In Java, every variable must be declared with a type and name before it can be referenced. The compiler cannot find a declaration for 'value' in the current scope, so it reports a 'cannot find symbol' error, which is the typical symptom of an undeclared variable.

Answer

The package is missing

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The class name is misspelled

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The variable 'value' is out of scope

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The variable 'value' is declared but not initialized

Question 8

A developer writes: int x; System.out.println(x); What is the result?

Accepted Answer

Compilation fails. B is correct because in Java, a local variable (such as `int x;` declared inside a method) must be initialized before it is used. The code attempts to print `x` without assigning a value, which violates the definite assignment rule and causes a compilation error.

Answer

null

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Runtime error

Answer

0

Question 9

Given: int day = 3; switch(day) { case 1: System.out.print("A"); case 2: System.out.print("B"); case 3: System.out.print("C"); case 4: System.out.print("D"); } What prints?

Accepted Answer

"CD". The switch statement does not have break statements, so after matching case 3, execution falls through to case 4, printing 'C' then 'D'. The output is 'CD'.

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"BCD"

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"C"

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"ABCD"

Question 10

Which two expressions evaluate to true? (Choose two)

Accepted Answer

10 > 5. The expression `10 > 5` uses the greater-than operator, which evaluates to `true` since 10 is indeed greater than 5. Option D is correct because `!false` evaluates to `true`, and the logical OR operator (`||`) returns `true` if at least one operand is `true`, so `false || true` yields `true`.

Answer

true && false

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'a' == 'b'

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3 < 3

Question 11

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.

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It is an unchecked exception.

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It can only be caught in a finally block.

Question 12

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.

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

Question 13

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 14

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 15

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

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The class is abstract

Question 16

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 17

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)

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public static int product(int nums...)

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

Question 18

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.

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Prototype pattern with cloning

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Builder pattern with a static inner class

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Factory pattern with a public constructor

Question 19

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

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false

Answer

It depends on the JVM

Question 20

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

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break is used to skip to next iteration

Answer

break exits the current loop iteration