1Z0-829 Practice Test 25 — 15 Questions

Question 1

A developer is implementing a method that reads a file and parses its contents. The method should ensure that any resources opened during the process are properly closed, even if an exception occurs. Which approach guarantees resource closure with minimal code?

Accepted Answer

Use try-with-resources with the resource declared in the try clause.. Option A is correct because try-with-resources automatically closes any resource that implements `AutoCloseable` (or `Closeable`) at the end of the try block, regardless of whether an exception occurs. This guarantees resource closure with minimal code, as the developer does not need to write explicit `close()` calls or manage finally blocks.

Answer

Use a try-catch block and close the resource inside the catch block.

Answer

Use a try block followed by a finally block without catch.

Answer

Use a try-catch-finally block and call close() in the finally block.

Question 2

Which of the following is a checked exception in Java?

Accepted Answer

SQLException. SQLException is a checked exception because it extends Exception directly (not RuntimeException). Checked exceptions must be either caught with a try-catch block or declared in the method signature using 'throws'. SQLException is thrown by JDBC API methods when database access errors occur, forcing the developer to handle potential SQL failures at compile time.

Answer

NullPointerException

Answer

ArrayIndexOutOfBoundsException

Answer

IllegalArgumentException

Question 3

A method catches multiple exceptions using a multi-catch clause. Which statement about the exceptions in a multi-catch clause is correct?

Accepted Answer

The exceptions must be disjoint; if one is a subclass of another, the code will not compile.. Option A is correct because Java requires that exception types in a multi-catch clause be disjoint (i.e., not in a subclass/superclass relationship). If one exception is a subclass of another, the code will not compile because the catch block would be unreachable for the subclass exception, violating the rule that catch blocks must be ordered from most specific to most general. This ensures that the multi-catch clause is unambiguous and that each exception type is distinct.

Answer

All exceptions in a multi-catch must be unchecked exceptions.

Answer

The multi-catch clause can have up to three exception types.

Answer

The exceptions can be in any order, and the first matching catch handles the exception.

Question 4

Consider the following code:

public void process() throws Exception {
    try {
        riskyMethod();
    } catch (IOException | SQLException e) {
        throw e;
    }
}

Assuming riskyMethod() declares both IOException and SQLException, what is the result?

Accepted Answer

The code compiles and runs correctly.. In Java 7+, multi-catch variables are implicitly final, so they can be rethrown without a cast. The compiler knows that the thrown exception is exactly one of the caught types (IOException or SQLException), and since both are checked exceptions declared in the method signature, the code compiles and runs correctly. Option D is correct.

Answer

Compilation fails because you cannot rethrow a multi-catch variable.

Answer

Compilation fails because the catch variable must be cast to Exception.

Answer

The code compiles, but throws a ClassCastException at runtime.

Question 5

Given an exception chain where a custom exception is created with a cause, which method is used to set the cause after construction?

Accepted Answer

initCause(Throwable). Option D is correct because `initCause(Throwable)` is the method provided by the `Throwable` class to set the cause of an exception after the exception has been constructed. This is useful when the exception must be created without a cause (e.g., via a no-arg constructor) and the cause is determined later. The cause can only be set once; a second call will throw an `IllegalStateException`.

Answer

The cause can only be set via constructor.

Answer

setCause(Throwable)

Answer

addSuppressed(Throwable)

Question 6

Given the following code snippet inside a method:

try {
    // risky code
} catch (IOException | SQLException e) {
    // handle
}

What is the implicit type of the exception variable 'e' in the catch block?

Accepted Answer

It is of type Exception.. In Java, when a multi-catch clause catches multiple exception types (e.g., IOException | SQLException), the compiler infers the catch parameter's type as the closest common superclass that is not Object or Throwable. Since IOException and SQLException both extend Exception directly, the implicit type of 'e' is Exception. This allows the catch block to handle both exception types polymorphically.

Answer

It is of type Object.

Answer

It is of type Throwable.

Answer

It is either IOException or SQLException.

Question 7

What is the result of executing the code in the exhibit?

Accepted Answer

The code does not compile because methodA does not declare that it throws Exception.. The code does not compile because methodA explicitly throws an IOException, but the catch block in main catches Exception (a broader type). However, the compiler performs improved rethrow analysis only when the exception parameter is effectively final and the catch block is multi-catch or rethrows a checked exception that is declared in the method signature. Here, methodA does not declare that it throws Exception, and the catch block catches Exception, which is not a declared exception in methodA's throws clause, causing a compilation error.

Answer

The code compiles and prints 'Caught in main: IOException' because the compiler uses improved rethrow analysis.

Answer

Prints: Caught in main: Exception

Answer

Prints: Caught in main: IOException

Question 8

Which TWO statements about try-with-resources are true? (Choose two.)

Accepted Answer

If both the try block and the close method throw exceptions, the close exception is suppressed.. Option B is correct because when both the try block and the close method throw exceptions, the exception from the close method is suppressed and added to the suppressed exceptions list of the exception thrown by the try block. This behavior is defined by the try-with-resources specification in Java, ensuring that the primary exception is not masked by resource-closing exceptions.

Answer

Resources are closed in the order they are declared.

Answer

Only a single resource can be managed in a try-with-resources statement.

Answer

Resources are closed after the catch block if an exception occurs.

Question 9

What happens when a finally block throws an exception?

Accepted Answer

The exception from the try block is suppressed and the finally exception is reported.. Option D is correct because when a finally block throws an exception, the JVM suppresses the exception that was thrown from the try block (if any) and propagates the exception thrown from the finally block. This behavior is defined in the Java Language Specification (JLS §14.20.2) and ensures that the finally block's exception takes precedence, as the finally block is executed after the try block completes abruptly.

Answer

The JVM logs both exceptions and then terminates the thread.

Answer

The exception from the try block is propagated and the finally exception is ignored.

Answer

Both exceptions are reported as suppressed exceptions of a new exception.

Question 10

Which THREE statements about exception handling are true? (Choose three.)

Accepted Answer

Multi-catch syntax uses the pipe symbol (|) between exception types.. Option C is correct because Java's multi-catch syntax allows a single catch block to handle multiple exception types by separating them with the pipe symbol (|). This reduces code duplication when different exceptions require the same handling logic.

Answer

The variable in a catch clause is effectively final only when using multi-catch syntax.

Answer

A finally block is mandatory in a try-with-resources statement.

Question 11

A developer wants to ensure that a block of code always executes regardless of whether an exception occurs or not, and that any exception thrown in the block is not swallowed. Which construct should be used?

Accepted Answer

try-finally. The try-finally construct ensures that the finally block always executes after the try block, regardless of whether an exception occurs, and it does not catch or swallow any exception. This meets the requirement of guaranteed execution without suppressing the exception, as the exception propagates up the call stack.

Answer

try-catch with empty catch block

Answer

try-catch-finally with catch that rethrows the exception

Answer

try-with-resources without catch

Question 12

Consider try-with-resources where resource1 is opened first, then resource2. During closing, both throw exceptions. Which exception is propagated to the caller?

Accepted Answer

The exception from resource2 (closed first) with resource1's exception as suppressed.. In try-with-resources, resources are closed in the reverse order of their declaration. Resource2 (declared second) is closed first, and resource1 (declared first) is closed last. If both throw exceptions during closing, the exception from the first resource closed (resource2) is propagated to the caller, and the exception from the second resource closed (resource1) is added as a suppressed exception. This matches option B.

Answer

The exception from resource1 (closed last) with resource2's exception as suppressed.

Answer

Only the exception from the resource declared first is propagated.

Answer

Both exceptions are wrapped in a new exception.

Question 13

Which of the following is a checked exception in Java?

Accepted Answer

IOException. Option C is correct because IOException is a checked exception in Java. Checked exceptions are subclasses of Exception (excluding RuntimeException and its subclasses), and the compiler enforces that they are either caught or declared in the method's throws clause. IOException directly extends Exception, making it a checked exception that must be handled at compile time.

Answer

NullPointerException

Answer

ArithmeticException

Answer

IllegalArgumentException

Question 14

Which TWO of the following are unchecked exceptions? (Choose two.)

Accepted Answer

NullPointerException. NullPointerException (option C) is an unchecked exception because it extends RuntimeException, which means it is not checked at compile time. The Java compiler does not require you to handle or declare NullPointerException, making it an unchecked exception.

Answer

SQLException

Answer

Exception

Answer

IOException

Question 15

Which two statements are true about FileInputStream? (Select two.)

Accepted Answer

It extends java.io.InputStream.. Option B is correct because FileInputStream directly extends java.io.InputStream, inheriting its abstract methods for reading bytes from a file. Option C is correct because FileInputStream implements java.io.Closeable, which extends AutoCloseable, allowing it to be used in try-with-resources statements for automatic resource management.

Answer

It supports mark() and reset().

Answer

It reads data in big-endian order.

Answer

It can be used to read characters.