1Z0-811 Practice Test 31 — 15 Questions

Question 1

Which TWO statements are true about the finally block in exception handling? (Select exactly 2)

Accepted Answer

The finally block is executed even if the try block contains a return statement.. The finally block is always executed regardless of whether an exception is thrown or caught, and even if the try block contains a return statement. The Java Language Specification (JLS §14.20.2) guarantees that the finally block executes after the try block and any associated catch blocks, but before control is transferred to the caller, ensuring cleanup code runs.

Answer

The finally block is executed only if an exception is thrown.

Answer

The finally block can be omitted only if the try block does not throw any checked exception.

Answer

The finally block is executed only if no exception is thrown.

Question 2

Arrange the steps to use the Scanner class to read user input in Java in the correct order.

Accepted Answer

1. Import java.util.Scanner; 2. Create Scanner object: Scanner sc = new Scanner(System.in); 3. Prompt user: System.out.print("Enter value: "); 4. Read input: String input = sc.nextLine(); 5. Close scanner: sc.close();. First import Scanner, then create an instance, prompt user, read input, and finally close the scanner.

Answer

1. Create Scanner object: Scanner sc = new Scanner(System.in); 2. Import java.util.Scanner; 3. Prompt user: System.out.print("Enter value: "); 4. Read input: String input = sc.nextLine(); 5. Close scanner: sc.close();

Answer

1. Import java.util.Scanner; 2. Prompt user: System.out.print("Enter value: "); 3. Create Scanner object: Scanner sc = new Scanner(System.in); 4. Read input: String input = sc.nextLine(); 5. Close scanner: sc.close();

Answer

1. Import java.util.Scanner; 2. Create Scanner object: Scanner sc = new Scanner(System.in); 3. Read input: String input = sc.nextLine(); 4. Close scanner: sc.close(); 5. Prompt user: System.out.print("Enter value: ");

Question 3

What is the output of the following code? int i = 0; i = i++ + ++i; System.out.println(i);

Accepted Answer

2. The expression `i = i++ + ++i` evaluates as follows: initially `i = 0`. In `i++`, the post-increment operator returns the current value (0) and then increments `i` to 1. Then `++i` pre-increments `i` from 1 to 2 and returns 2. The sum is 0 + 2 = 2, which is assigned to `i`, overwriting the intermediate increments. Thus, the final output is 2.

Answer

3

Answer

0

Answer

1

Question 4

Which THREE of the following are valid loop constructs in Java?

Accepted Answer

while loop. The correct answers are A (while loop), B (for loop), and E (do-while loop) because all three are valid loop constructs in Java. The while loop repeats as long as a condition is true, the for loop provides a compact iteration mechanism, and the do-while loop guarantees at least one execution.

Answer

switch statement

Answer

if statement

Question 5

Refer to the exhibit. What happens when you compile this code?

Accepted Answer

Compilation fails because num is final. The code fails to compile because the variable `num` is declared as `final`, meaning its value cannot be changed after initialization. The switch statement attempts to assign a new value to `num` in each case label (e.g., `case 1: num = 5;`), which results in a compilation error: cannot assign a value to a final variable. This is not a type mismatch; it is a violation of the final constraint.

Answer

Compilation fails because of type mismatch

Answer

Prints "Five"

Answer

Prints nothing

Question 6

Which THREE of the following are valid types that can be used as a switch expression in Java (as of Java 8)?

Accepted Answer

String. In Java 8, a switch expression can use `String`, `char`, and `int` as valid types. `String` was added in Java 7, and `char` and `int` are among the original primitive types supported. `long` and `boolean` are not allowed because `long` is a 64-bit type not supported by the switch statement's underlying `tableswitch` or `lookupswitch` bytecode instructions, and `boolean` has only two values, making it unsuitable for switch's multi-branch logic.

Answer

long

Answer

boolean

Question 7

What is the value printed?

Accepted Answer

2. The while loop condition is `x < 2`, so the loop executes while x is less than 2. Initially x=0. In the first iteration, x becomes 1; in the second, x becomes 2. After the second iteration, x=2, the condition `2 < 2` is false, so the loop stops. The code prints the value of x, which is 2 after the loop exits.

Answer

3

Answer

5

Answer

0

Question 8

Refer to the exhibit. What is the most likely cause?

Accepted Answer

The code tries to access index 5 of a 5-element array.. Java arrays are zero-indexed, meaning a 5-element array has valid indices 0 through 4. Accessing index 5 attempts to read beyond the array bounds, causing an ArrayIndexOutOfBoundsException at runtime. This is a classic off-by-one error where the code mistakenly uses the array length as the index.

Answer

The array has 6 elements.

Answer

The code tries to access index 4 of a 5-element array.

Answer

The code has a syntax error.

Question 9

A company's application uses a switch statement to handle different user roles. The code currently has a bug where after processing one role, it unintentionally executes the next role's logic. Which concept is being misused?

Accepted Answer

Missing break statements causing fall-through. In Java, a switch statement without break statements causes fall-through, where execution continues into subsequent case blocks even after a match is found. This is exactly the bug described: after processing one role, the code unintentionally executes the next role's logic because no break terminates the case.

Answer

Incorrect default case

Answer

Using enum in switch

Answer

Using string in switch (Java 7+)

Question 10

A developer writes two methods: public void process(int a) { ... } and public void process(double a) { ... }. Which method is called by process(10)?

Accepted Answer

The method with int parameter. Java selects the most specific overloaded method at compile time. When calling process(10), the integer literal 10 is an int, so the compiler prefers the method with the int parameter over the double parameter, as no implicit widening conversion is required.

Answer

The method with double parameter

Answer

Compilation error: ambiguous call

Answer

Runtime error: NoSuchMethod

Question 11

An application throws 'java.lang.OutOfMemoryError: Java heap space'. Which JVM option can help generate diagnostic information to identify the cause?

Accepted Answer

-XX:+HeapDumpOnOutOfMemoryError. XX:+HeapDumpOnOutOfMemoryError instructs the JVM to generate a heap dump file when an OutOfMemoryError occurs, which can be analyzed to identify memory leaks or other causes. Option A (-version) prints the Java version and does not help with diagnostics. Option B (-verbose:gc) prints garbage collection details but does not produce a heap dump at the time of failure. Option D (-Xmx) sets the maximum heap size, which may delay or prevent the error but does not provide diagnostic information about the cause.

Answer

-version

Answer

-verbose:gc

Answer

-Xmx

Question 12

Given a method that catches Exception and then throws a RuntimeException, what is the effect?

Accepted Answer

The method can throw RuntimeException without declaring it.. In Java, RuntimeException is an unchecked exception, meaning it does not need to be declared in a method's throws clause. The catch block catches Exception (which includes RuntimeException), and then throws a new RuntimeException. Since RuntimeException is unchecked, the method can throw it without declaring it, making option B correct.

Answer

The RuntimeException will not propagate if caught.

Answer

The method must declare throws RuntimeException.

Answer

The catch block cannot throw a RuntimeException because it is caught as Exception.

Question 13

A method returns a String. The team debates using == vs equals(). Which correctly describes String comparison in Java?

Accepted Answer

== may return true for two different references if they point to the same interned string.. The == operator in Java compares object references, not content. However, due to string interning, two different String variables that reference the same interned string literal will have the same memory reference, causing == to return true. This is a special case that can mislead developers into thinking == compares content.

Answer

== compares the content of two Strings.

Answer

== always returns false for different String objects, even if content is same.

Answer

equals() compares the memory addresses.

Question 14

What is the value of y after executing the following code?
```java
int y = 10 + 12;
```

Accepted Answer

22. The code snippet `int y = 10 + 12;` performs integer addition, resulting in y = 22. Java's primitive arithmetic follows standard rules, so adding 10 and 12 yields 22 without any overflow or conversion issues.

Answer

20

Answer

21

Answer

23