1Z0-811 Timed Practice Test 5 — 10 Questions

Question 1

What is the value of sum printed?

Accepted Answer

3. The correct answer is C because the loop iterates from i=0 to i<3, incrementing i by 1 each time. Inside the loop, sum is updated as sum = sum + i, so sum becomes 0+0=0, then 0+1=1, then 1+2=3. After the loop ends, sum is 3.

Answer

6

Answer

0

Answer

1

Question 2

A method 'public static int findMax(int[] numbers)' returns the maximum value in the array. Which implementation correctly handles an empty array by returning 0?

Accepted Answer

if(numbers.length == 0) return 0; int max = numbers[0]; for(int i=1; i<numbers.length; i++) if(numbers[i] > max) max = numbers[i]; return max;. Option D correctly handles an empty array by checking `numbers.length == 0` and returning 0 before attempting to access `numbers[0]`, which would throw an `ArrayIndexOutOfBoundsException` on an empty array. It then initializes `max` to the first element and iterates from index 1, ensuring all elements are compared correctly even if all numbers are negative.

Answer

int max = 0; for(int n: numbers) if(n > max) max = n; return max;

Answer

int max = numbers[0]; for(int i=1; i<numbers.length; i++) if(numbers[i] > max) max = numbers[i]; return max;

Answer

if(numbers.length == 0) return 0; int max = 0; for(int n: numbers) if(n > max) max = n; return max;

Question 3

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

Accepted Answer

The method can modify the elements of the array.. Option B is correct because Java passes object references by value. When an array is passed to a method, the method receives a copy of the reference to the array object. This copy still points to the same array object in heap memory, so the method can modify the elements of the array through that reference. These modifications are visible to the caller because they affect the same underlying array object.

Answer

The method can reassign the original array variable to a new array.

Answer

The method must return the array to reflect any changes.

Answer

The method cannot determine the size of the array.

Question 4

Which of the following correctly describes the effect of the method call 'Arrays.sort(myArray)' on an array of objects that do not implement Comparable?

Accepted Answer

A ClassCastException is thrown at runtime.. When `Arrays.sort(myArray)` is called on an array of objects that do not implement the `Comparable` interface, the method attempts to cast elements to `Comparable` to compare them. Since the objects do not implement `Comparable`, a `ClassCastException` is thrown at runtime. The `Arrays.sort(Object[])` method requires that all elements implement `Comparable`; otherwise, it cannot determine a natural ordering.

Answer

The code does not compile because Arrays.sort requires a Comparator.

Answer

The array is sorted using the natural order of the elements.

Answer

The array is sorted using the order defined by the elements' equals method.

Question 5

A developer writes a class 'Vehicle' with a method 'move()' that prints 'Vehicle moves'. A subclass 'Car' overrides 'move()' to print 'Car moves'. Given: Vehicle v = new Car(); v.move(); What is the output?

Accepted Answer

Car moves. Option D is correct because Java uses dynamic method dispatch (runtime polymorphism). Even though the reference variable is of type 'Vehicle', the actual object is a 'Car' instance. At runtime, the JVM calls the overridden 'move()' method of the 'Car' class, printing 'Car moves'.

Answer

Vehicle moves

Answer

Runtime exception

Answer

Compilation fails

Question 6

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 in Java allows multiple methods to share the same name but have different parameter lists (different number, type, or order of parameters). This enables compile-time polymorphism, where the compiler selects the appropriate method based on the arguments provided at the call site.

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 7

A class 'Base' has a method 'public void display() throws IOException'. Subclass 'Derived' overrides display(). Which exception specifications are allowed in the overriding method?

Accepted Answer

public void display() throws FileNotFoundException. In Java, an overriding method can throw the same exception, a subclass of the exception thrown by the parent method, or no exception at all. The parent method throws IOException, so the overriding method may throw FileNotFoundException (a subclass of IOException). This follows the rule that the overriding method cannot throw a broader checked exception than the overridden method.

Answer

public void display() throws SQLException

Answer

public void display() throws Exception

Answer

public void display() throws Throwable

Question 8

Given the compilation error above, which fix would resolve the error?

Accepted Answer

Wrap the code in a try-catch block for FileNotFoundException.. Option C is correct because the compilation error indicates that the code uses a constructor or method that throws a checked `FileNotFoundException` (a subclass of `IOException`). In Java, checked exceptions must be either caught with a try-catch block or declared in the method signature. Wrapping the code in a try-catch block for `FileNotFoundException` handles the exception locally, resolving the compilation error without altering the method signature.

Answer

Add a throws FileNotFoundException clause to the main method.

Answer

Change FileReader to BufferedReader.

Answer

Use FileInputStream instead.

Question 9

Which statement about the Java compiler is true?

Accepted Answer

It translates Java source code into bytecode.. The Java compiler (javac) translates human-readable Java source code (.java files) into platform-independent bytecode (.class files). This bytecode is then executed by the Java Virtual Machine (JVM), not directly by the operating system. Option D correctly identifies this translation step.

Answer

It translates Java source code into native machine code.

Answer

It produces executable files that run directly on the OS.

Answer

It executes Java programs.

Question 10

What is the output of: System.out.println(new Manager("Alice", 5).getName());

Accepted Answer

Alice. Option C is correct because the code creates a new Manager object with the name "Alice" and a level of 5, then calls getName() on it. Assuming Manager extends a class (likely Employee) that has a constructor setting the name field via super(name), getName() returns the stored name "Alice". The code compiles and runs without exception, printing "Alice".

Answer

Runtime exception

Answer

Compilation fails

Answer

null

1Z0-811 Timed Practice Test 5 — 10 Questions

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1Z0-811 Timed Practice Test 5 — 10 Questions

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