1Z0-811 Practice Test 2 — 30 Questions

Question 1

int count = 0;
for (int i = 0; i < 5; i++) {
    if (i == 2) {
        continue;
    }
    count++;
}
System.out.println(count);

What is the output of the program?

Accepted Answer

4. The loop runs i from 0 to 4. When i equals 2, the continue statement skips the rest of the loop body, so count++ is not executed for that iteration. For the other four iterations (i = 0, 1, 3, 4), count is incremented, giving a final value of 4.

Answer

The loop does not compile.

Answer

5

Answer

2

Question 2

Given: boolean a = false; boolean b = true; boolean c = true; System.out.println(a || b && c); What is the output?

Accepted Answer

true. In Java, the logical AND operator (&&) has higher precedence than the logical OR operator (||). Therefore, the expression `a || b && c` is evaluated as `a || (b && c)`. Given `a = false`, `b = true`, and `c = true`, `b && c` evaluates to `true`, and then `false || true` evaluates to `true`. Thus, the output is `true`, making option D correct.

Answer

false

Answer

Compilation fails

Answer

None of the above

Question 3

A developer compiles a Java application using the command `javac -d bin src/com/example/App.java`. Which of the following is true?

Accepted Answer

The compiled .class files are placed in the `bin` directory maintaining the package structure.. The `-d` option in the `javac` command specifies the destination directory for compiled `.class` files. When `-d bin` is used, the compiler places the `.class` files into the `bin` directory, preserving the package directory structure (e.g., `bin/com/example/App.class`). This is the standard behavior for organizing compiled output separately from source code.

Answer

The compiler searches for source files in the `bin` directory.

Answer

The compiler creates a JAR file named `App.jar` in the `bin` directory.

Answer

The compiler compiles the code into a named module.

Question 4

Which of the following correctly uses the shorthand array initializer to declare and initialize an array of strings with the elements "A", "B", and "C"?

Accepted Answer

String[] arr = {"A", "B", "C"};. Option D correctly uses the shorthand array initializer with curly braces directly in the declaration. Option A uses the full syntax with the 'new' keyword, which is also valid but not the shorthand. Option B is wrong because it uses parentheses. Option C is wrong because it uses square brackets.

Answer

String[] arr = new String[] {"A", "B", "C"};

Answer

String[] arr = ("A", "B", "C");

Answer

String[] arr = ["A", "B", "C"];

Question 5

Given the code: String s1 = "Java"; String s2 = new String("Java"); if (s1 == s2) { System.out.print("Equal"); } else { System.out.print("Not Equal"); } What is the output?

Accepted Answer

Not Equal. The == operator compares object references, not the actual string content. s1 is a string literal stored in the string pool, while s2 is a new String object created on the heap, so they refer to different memory locations, making the comparison false and printing 'Not Equal'.

Answer

Runtime error

Answer

Compilation error

Answer

Equal

Question 6

A developer is working on a Java application that processes sensor data. The code uses a class 'SensorDataProcessor' which directly instantiates specific sensor classes like 'TemperatureSensor' and 'PressureSensor' inside its methods. The team wants to make the system extensible to support new sensor types without modifying the processor class. Which design change best achieves this?

Accepted Answer

Define a Sensor interface and use dependency injection to pass sensor objects to the processor. The Open/Closed Principle says classes should be open for extension but closed for modification. By defining a Sensor interface and injecting Sensor implementations into SensorDataProcessor, the processor depends on an abstraction rather than concrete classes, so new sensor types can be added without touching the processor code. Dependency injection also improves testability because mock sensors can be substituted in unit tests. This is the canonical Strategy/DI pattern for decoupling.

Answer

Make SensorDataProcessor abstract and subclass it for each sensor

Answer

Use a static factory method in SensorDataProcessor to create sensors

Answer

Create a separate configuration file listing sensors and use reflection to instantiate them

Question 7

A developer writes a utility that must return two values, a minimum and a maximum, from an array of measurements. The method below is proposed:

public static int[] minMax(int[] values) {
    // implementation omitted
    return new int[]{min, max};
}

Which statement about this method signature and return statement is correct?

Accepted Answer

The method compiles, and the returned array is a distinct object whose length is 2.. Array types are legitimate return types because arrays are objects, and an array initializer on a return statement allocates a brand-new two-element array on each invocation. The caller therefore receives an independent object whose length is fixed at two by the initializer.

Answer

The method compiles only if the array initializer is replaced with a call to Arrays.copyOf on the input parameter.

Answer

The method cannot compile because Java methods may return only primitive values or single objects, never arrays.

Answer

The method compiles, but the returned array automatically shares storage with the input parameter values.

Question 8

Which THREE of the following expressions compile without error? (Choose 3)

Accepted Answer

byte b = 1 + 2;. Option A is correct because the expression 1 + 2 is a compile-time constant int whose value (3) fits within the byte range, so the implicit narrowing assignment to byte is permitted. Option C is correct because an int literal 10 is widened automatically to double in the assignment double d = 10;. Option D is correct because (false || true) is a valid boolean expression using the logical OR operator, and its result is assignable to a boolean variable. Option B is not correct because 5L is a long and 10 is an int; the sum is long, which cannot be assigned to an int without an explicit cast. Option E is not correct because 5.5 is a double literal, and assigning a double to a float requires an explicit cast (or an f suffix such as 5.5f).

Answer

int i = 5L + 10;

Answer

float f = 5.5;

Question 9

Which operator is used to compare two strings for value equality in Java?

Accepted Answer

equals(). The equals() method in Java's String class compares the actual character sequences of two strings for value equality. Unlike the == operator, which checks reference equality (whether two references point to the same object in memory), equals() performs a lexicographic comparison of the string contents, returning true if and only if both strings have the same length and the same characters in the same order.

Answer

compareTo()

Answer

=

Answer

==

Question 10

A team is implementing a search algorithm that iterates over an array of integers. The loop should stop as soon as the target value is found. Which loop construct is most appropriate?

Accepted Answer

For loop with break. A for loop with a break statement is the most appropriate construct because it allows iteration over the array with an explicit exit condition the moment the target value is found. The break statement immediately terminates the loop, avoiding unnecessary iterations and clearly expressing the early-exit intent. This is idiomatic Java and matches the requirement to stop as soon as the target is located.

Answer

While loop with a flag variable

Answer

Enhanced for loop with continue

Answer

Do-while loop

Question 11

What is the scope of a variable declared inside a for loop?

Accepted Answer

Only inside the loop block. In Java, a variable declared inside a for loop (including the initialization block or the loop body) has block scope, meaning it is only accessible within the loop block itself. This is defined by the Java Language Specification (JLS §6.10), which states that the scope of a local variable declaration is the rest of the block in which the declaration appears. Once the loop completes, the variable goes out of scope and cannot be referenced.

Answer

Inside the package

Answer

Inside the class

Answer

Inside the entire method

Question 12

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

Question 13

Which TWO are valid ways to pass an array to a method in Java?

Accepted Answer

myMethod(new int[]{1,2,3});. Option A is correct because it uses the valid anonymous array syntax new int[]{1,2,3}, which creates an int array and passes it directly as the method argument. Option B is correct because it first declares and initializes an int array with int[] arr = {1,2,3}, then passes the array reference arr to myMethod, which is the standard way to pass an array variable. Option C is incorrect because myMethod(1, 2, 3) passes three separate int arguments, not an array, unless the method specifically uses varargs, which is not stated. Option D is incorrect because the syntax int[] {1,2,3} is invalid; an anonymous array must use new int[]{1,2,3}. Option E is incorrect because Java does not allow specifying both an array size and an initializer list, so new int[5] {1,2,3,4,5} is illegal.

Answer

myMethod(1, 2, 3);

Answer

myMethod(int[] {1,2,3});

Answer

myMethod(new int[5] {1,2,3,4,5});

Question 14

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

Accepted Answer

private. The private access modifier restricts a member's visibility to only the class in which it is declared. This is the most restrictive access level in Java, ensuring that no other class—not even subclasses or classes in the same package—can access the member directly. Therefore, private is the correct answer for allowing access only within the same class.

Answer

static

Answer

public

Answer

default (no modifier)

Answer

protected

Question 15

A method declares throws FileNotFoundException and SQLException. Which statement about the caller is true?

Accepted Answer

The caller must handle or declare both exceptions.. In Java, when a method declares checked exceptions (like FileNotFoundException and SQLException) in its throws clause, any caller must either handle each checked exception with a try-catch block or declare them in its own throws clause. The compiler enforces this rule to ensure that checked exceptions are properly accounted for, preventing unhandled checked exceptions from propagating unchecked.

Answer

The caller must catch only FileNotFoundException.

Answer

The caller can declare throws Exception to cover both.

Answer

The caller can ignore both exceptions.

Question 16

A developer needs to handle a specific checked exception, FileNotFoundException, but also wants to catch any other IOException that might occur. Which catch block ordering is correct?

Accepted Answer

catch (FileNotFoundException e) first, then catch (IOException e).. Checked exceptions must be caught in order from most specific to most general. FileNotFoundException is a subclass of IOException, so it must be caught first; otherwise, the more specific catch block would be unreachable and cause a compilation error. This ordering ensures that the developer can handle the specific FileNotFoundException separately while still catching any other IOException in the second block.

Answer

Use a multi-catch: catch (FileNotFoundException | IOException e).

Answer

catch (IOException e) first, then catch (FileNotFoundException e).

Answer

Use a single catch (Exception e).

Question 17

Which TWO statements are true about method overloading in Java?

Accepted Answer

Overloaded methods can have different parameter lists.. Option B is correct because method overloading is defined by methods sharing the same name but differing in their parameter lists, which may vary in the number, types, or order of parameters. Option C is correct because overloaded methods must share the same method name; that shared name is what makes them overloaded rather than simply distinct methods. Option A is incorrect because overloaded methods may have different numbers of parameters, which is one of the valid ways to distinguish them. Option D is incorrect because return type alone cannot distinguish overloaded methods, and overloads are not required to have different return types. Option E is incorrect because methods with different names are not overloaded; they are simply different methods.

Answer

Overloaded methods must have the same number of parameters.

Answer

Overloaded methods must have different return types.

Answer

Overloaded methods can have different names.

Question 18

A developer writes a utility method that accepts a variable number of int arguments and prints their sum. The method is declared as public static int sum(int... values). Which statement correctly describes how this method can be invoked?

Accepted Answer

It can be invoked with zero arguments, one int argument, or multiple int arguments.. A varargs parameter declared as int... values is compiled into an int[] parameter, and the compiler accepts zero or more int arguments at the call site, wrapping them into an array. This makes the method convenient for callers while keeping the implementation type-safe. The other invocation forms described are either overly restrictive or violate Java's type conversion rules.

Answer

It can be invoked with arguments of any numeric type, including double and long, because Java automatically widens them to int.

Answer

It must be invoked with at least one int argument; zero arguments causes a compile-time error.

Answer

It can be invoked only with an explicit int array, such as sum(new int[]{1,2,3}).

Question 19

A developer writes a for loop to process an array of temperatures. The loop must skip any temperature that is below zero and continue processing the remaining temperatures. Which change to the loop body correctly implements this requirement?

Accepted Answer

Insert an if statement that checks for a negative temperature and uses continue; to skip the rest of the current iteration.. The continue statement is designed to skip the remainder of the current loop iteration and move to the next one, which is exactly what is needed to ignore negative temperatures while processing the rest. Using break, return, or System.exit would stop the loop or program prematurely and leave valid temperatures unprocessed.

Answer

Insert an if statement that checks for a negative temperature and uses break; to exit the loop.

Answer

Insert an if statement that checks for a negative temperature and uses return; to leave the method.

Answer

Insert an if statement that checks for a negative temperature and uses System.exit(0); to stop the program.

Question 20

A developer writes the following code:

int x = 5;
switch (x) {
    case 1:
        System.out.print("One ");
    case 5:
        System.out.print("Five ");
    case 10:
        System.out.print("Ten ");
        break;
    default:
        System.out.print("Other ");
}

What is printed?

Accepted Answer

Five Ten. The switch expression x has the value 5, so execution jumps to the matching case 5 and prints "Five ". No break statement follows, so execution falls through into case 10, printing "Ten ". The break after case 10 ends the switch, so default is never reached. The result is the concatenation of both prints: Five Ten.

Answer

Five Ten Other

Answer

Five

Answer

Ten