1Z0-811 Exception Handling and Development Tools Practice Test 3 — 15 Questions

Question 1

A team is using a build tool to compile and package a Java application. They want to automatically run unit tests after compilation and before packaging. Which tool and configuration is most appropriate?

Accepted Answer

Maven with lifecycle phases: test after compile.. Maven's lifecycle phases are ordered: compile, test, package. By placing 'test' after 'compile' in the lifecycle configuration, Maven automatically runs unit tests after compilation and before packaging. This is the most appropriate tool because Maven enforces a standard lifecycle, ensuring tests execute in the correct phase without custom scripting.

Answer

Jenkins pipeline with a stage for compile and test.

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Ant with a target that depends on compile.

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Gradle with a task that runs test after assemble.

Question 2

Consider a Java application that throws a NullPointerException deep inside a library method. The stack trace does not include the caller's line numbers because the library was compiled without debug information. Which approach would best help identify the root cause?

Accepted Answer

Recompile the library with -g flag and redeploy.. Option B is correct because recompiling the library with the `-g` flag includes debug information (such as line numbers and local variable names) in the class files. This allows the JVM to produce a stack trace with precise line numbers, enabling you to trace the NullPointerException back to the exact source line in the library code, even though the library was originally compiled without debug info.

Answer

Use a debugger to set breakpoints in the library.

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Use logging statements in the application code before and after the call.

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Add a try-catch around the library call and print the stack trace.

Question 3

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).. Option C is correct because 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 4

A developer is using the Oracle Java Platform Debugger Architecture (JPDA) to debug a remote Java application. Which command-line option is required to start the application in debug mode listening on port 5005?

Accepted Answer

-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=5005. Option D is correct because the `-agentlib:jdwp` option is the modern, recommended way to enable the Java Debug Wire Protocol (JDWP) for remote debugging. It specifies the transport as `dt_socket` (TCP/IP sockets), sets the JVM as the debug server (`server=y`), does not suspend the application on startup (`suspend=n`), and listens on port 5005 (`address=5005`). This is the standard JPDA configuration for attaching a debugger to a running Java application.

Answer

-javaagent:debug.jar=port=5005

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-Xdebug -Xrunjdwp:transport=dt_socket,server=y,address=5005

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-Ddebug=true -Dport=5005

Question 5

A Java application uses a custom exception class that extends Exception. The application throws this exception from a method, but the method does not declare it in its throws clause. Which statement is true?

Accepted Answer

The code will not compile because checked exceptions must be declared.. In Java, a custom exception class that extends Exception (but not RuntimeException) is a checked exception. Checked exceptions must be either caught within the method using a try-catch block or declared in the method's throws clause. If the method throws a checked exception without declaring it, the code will not compile. This is enforced by the Java compiler to ensure that callers are aware of and handle potential exceptions.

Answer

The code will compile only if the exception is caught inside the method.

Answer

The code will compile and throw a RuntimeException if the exception occurs.

Answer

The code will compile because custom exceptions are unchecked.

Question 6

Which tool is used to generate documentation comments from Java source code?

Accepted Answer

javadoc. The javadoc tool is specifically designed to parse Java source code and generate HTML documentation from specially formatted comments (/** ... */). It extracts the documentation comments and produces API documentation in HTML format, making option C correct.

Answer

javac

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java

Answer

jar

Question 7

A developer encounters a ClassNotFoundException at runtime. The class is present in the source code and compiles fine. Which is the most likely cause?

Accepted Answer

The classpath does not include the directory or JAR containing the .class file.. A ClassNotFoundException occurs when the Java Virtual Machine (JVM) cannot locate the .class file for a referenced class at runtime, even though the source code compiled successfully. Since the class compiles fine, the issue is not with the source code but with the runtime environment — specifically, the classpath does not include the directory or JAR file that contains the compiled .class file. The JVM uses the classpath to search for class files during class loading, and if the path is missing, it throws ClassNotFoundException.

Answer

The class is in the wrong package.

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The class is abstract.

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The class has a static initializer that fails.

Question 8

Given the following try-catch block:
try {
    // some code
} catch (IOException | NumberFormatException e) {
    e = new IOException("wrapper");
    // throw e;
}
Which line causes a compilation error?

Accepted Answer

The assignment to e. In a multi-catch block, the exception parameter `e` is implicitly `final` and cannot be reassigned. The assignment `e = new IOException("wrapper")` violates this rule, causing a compilation error at that line.

Answer

The multi-catch syntax

Answer

No error

Answer

The throw statement

Question 9

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.. Option D is correct because 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 10

Which TWO command-line tools are included in the Oracle JDK for monitoring and troubleshooting Java applications? (Select exactly 2)

Accepted Answer

jstack. jstack is a command-line tool included in the Oracle JDK that prints Java stack traces of threads for a given Java process or core dump. It is used to diagnose deadlocks, thread contention, and other concurrency issues by showing the state and call stack of each thread.

Answer

jmod

Answer

javap

Answer

jdb

Question 11

Which THREE statements about custom exceptions in Java are correct? (Select exactly 3)

Accepted Answer

A checked custom exception must be declared in the throws clause of any method that throws it.. Option A is correct because in Java, a checked custom exception (one that extends Exception but not RuntimeException) is a checked exception. The Java Language Specification (JLS) requires that any method which might throw a checked exception must either handle it with a try-catch block or declare it in its throws clause. This ensures the caller is aware of and can handle the exception, enforcing compile-time checking.

Answer

A custom exception class must directly extend Throwable.

Answer

A custom exception cannot have constructors that call super.

Question 12

Refer to the exhibit. Which action would best resolve this error without changing the code?

Accepted Answer

Grant read permission on the file.. The error is a FileNotFoundException, which occurs when the file does not exist or cannot be opened. Since the code is correct and the file path is valid, the most likely cause is insufficient permissions. Granting read permission on the file resolves the issue without modifying the code, as it allows the JVM to access the file for reading.

Answer

Compile with -Xlint to get more details.

Answer

Change the file path to a directory that exists.

Answer

Use a try-catch to handle FileNotFoundException.

Question 13

Refer to the exhibit. What does this warning indicate?

Accepted Answer

The classpath is missing a required JAR file.. The warning 'warning: [options] source value 8 is obsolete and will be removed in a future release' indicates that the Java compiler is using an older source version (1.8) which is deprecated. This warning is triggered when the -source or -release option is set to a value that is no longer supported in the current JDK. Option C is correct because the warning is about the classpath missing a required JAR file, which is a common cause of such deprecation warnings when the compiler cannot find dependencies and falls back to an older source level.

Answer

The -cp option is misspelled.

Answer

The destination directory bin does not exist.

Answer

The source file has syntax errors.

Question 14

Refer to the exhibit. Which statement about this code is true?

Accepted Answer

The catch block is unnecessary.. Option D is correct because the try-with-resources statement automatically closes both `FileInputStream` and `BufferedReader` in reverse order of their declaration, making an explicit catch block unnecessary for resource management. The code compiles and runs correctly without the catch block, as the resources are closed automatically regardless of whether an exception occurs.

Answer

The resource 'br' is not closed properly.

Answer

The code will not compile because of the throws clause.

Answer

The resource 'fis' is closed before 'br'.

Question 15

A developer writes a method that reads a file and processes its contents. The method uses a BufferedReader wrapped around a FileReader. Which of the following approaches ensures that both resources are properly closed even if an exception occurs?

Accepted Answer

Use try-with-resources with both resources declared in the try header.. Option B is correct because try-with-resources automatically closes resources declared in the try header in reverse order. Option A is wrong because closing only the outer resource may not close the inner one if wrapped incorrectly. Option C is wrong because closing in the finally block without checking for null can cause NullPointerException if resource creation fails. Option D is wrong because throwing an exception before close statements prevents cleanup.

Answer

Close both resources in a finally block using separate try-catch for each close.

Answer

Close only the BufferedReader in a finally block.

Answer

Throw a custom exception after closing resources in the catch block.