1Z0-811 Multiple Select — 20 Questions

Question 1

Which THREE are primitive data types in Java? (Choose three.)

Accepted Answer

int. Option A (int) is correct because int is one of Java's eight built-in primitive types, representing a 32-bit signed two's-complement integer. Option B (boolean) is correct because boolean is a primitive type that holds only the values true or false, with a size defined by the JVM. Option D (double) is correct because double is a primitive type storing a 64-bit IEEE 754 double-precision floating-point value. Option C (String) is not a primitive; it is a reference type, specifically a final class in java.lang, and its literals are interned objects. Option E (Object) is also a reference type, the root class of the Java class hierarchy, not a primitive.

Answer

String

Answer

Object

Question 2

Which three of the following are valid ways to declare and initialize a variable of type int? (Choose three.)

Accepted Answer

int b = 0xA;. Option A (int b = 0xA;) is valid because Java supports hexadecimal integer literals prefixed with 0x, and 0xA equals decimal 10, which fits in an int. Option C (int d = 010;) is valid because a leading zero denotes an octal literal, and 010 is octal for decimal 8, a legal int value. Option E (int a = 10;) is valid because 10 is a standard decimal int literal assigned directly to an int variable. Option B (int e = 10.0;) is invalid because 10.0 is a double literal and cannot be assigned to an int without an explicit cast. Option D (int c = 0b2;) is invalid because the 0b prefix denotes a binary literal, and the digit 2 is not permitted in binary.

Answer

int e = 10.0;

Answer

int c = 0b2;

Question 3

Which TWO methods correctly modify the passed array in place?

Accepted Answer

public void zeroOut(int[] a) { for (int i = 0; i < a.length; i++) a[i] = 0; }. It directly modifies each element of the passed array by assigning 0 to a[i] within the loop. In Java, when an array is passed to a method, the method receives a reference to the same array object, so changes to the array's elements are reflected in the caller's array.

Answer

public void reset(int[] a) { a = new int[10]; }

Answer

public void swap(int[] a) { int[] temp = a; a = new int[1]; a[0] = temp[0]; }

Answer

public void setFirst(int[][] a) { a = new int[1][1]; a[0][0] = 5; }

Question 4

A developer is writing a switch statement in Java to route a shipment based on a String region code. Which two statements about this switch statement are true? (Choose two.)

Accepted Answer

Each case label must be a compile-time constant expression, and duplicate labels in the same switch cause a compile-time error.. Java allows String switch expressions and compares them by content, so equal text selects the same case even for distinct objects. Case labels must be compile-time constants and must be unique within the switch. Fall-through, not automatic termination, occurs when break is omitted, and the default label remains optional rather than mandatory.

Answer

If a matching case has no break statement, execution stops automatically at the end of that case.

Answer

The default label is required in every switch statement, and omitting it prevents compilation.

Answer

A switch on a String can only be used inside a method that declares throws Exception.

Question 5

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 6

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 7

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 8

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 9

Which FOUR statements about the main method are correct? (Choose four.)

Accepted Answer

It must be declared void.. Options A, B, and C are correct because the main method must be declared void, static, and public for the JVM to invoke it as the entry point of a program. Option E is also correct: Java allows overloading of the main method; you can define multiple main methods with different parameter lists, but only the one with the standard signature `public static void main(String[] args)` is used as the program entry point. Option D is incorrect because the main method must not return a value; its return type must be void.

Answer

It must return an int.

Question 10

A developer is reviewing code that uses assertions. Which two statements about Java assertions are true? (Choose two.)

Accepted Answer

Assertions are enabled at runtime using the -ea command-line option.. Assertions are disabled by default and must be enabled with -ea at runtime. When enabled and an assertion fails, an AssertionError is thrown. They are intended for internal invariant checks, not for validating public method parameters or handling recoverable errors, which should use exceptions.

Answer

Assertions can be used to validate parameters of public methods.

Answer

Assertions are enabled by default when running a Java application.

Answer

Assertions can be used to handle recoverable runtime errors gracefully.

Question 11

Which THREE are benefits of Java's platform independence? (Choose three.)

Accepted Answer

Ability to run on any device with a JVM. Option A is correct because Java source is compiled to bytecode that executes on the Java Virtual Machine, so any device providing a compatible JVM can run the same class files regardless of underlying OS or CPU architecture. Option B is correct because this portability is precisely the 'write once, run anywhere' (WORA) promise: a single compiled artifact is not recompiled per platform, only interpreted/JIT-compiled by the local JVM. Option E is correct because the JVM's class loader, bytecode verifier, and SecurityManager architecture provide a sandbox that constrains untrusted code, a security benefit tied to running on the managed JVM layer. Option C is not a benefit of platform independence—bytecode is typically interpreted or JIT-compiled and generally slower to warm up than optimized native code, so it is not a portability advantage. Option D is a feature of the Java runtime (garbage collection) but is unrelated to platform independence, so it does not belong.

Answer

Faster execution compared to native code

Answer

Automatic memory management

Question 12

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 a checked exception (any subclass of Exception that is not a subclass of RuntimeException) is subject to the Java checked-exception rule, so any method that throws it must declare it in its throws clause or the code will not compile. Option B is correct because a custom exception can be designed as either checked (extending Exception) or unchecked (extending RuntimeException), giving the developer control over whether callers are forced to handle it. Option C is correct because the defining characteristic of an unchecked exception in Java is that it extends RuntimeException (or one of its subclasses), so an unchecked custom exception must extend RuntimeException. Option D is incorrect because a custom exception need not extend Throwable directly; it typically extends Exception or RuntimeException, which already inherit from Throwable. Option E is incorrect because custom exceptions can and commonly do define constructors that call super(...) to pass messages or causes to the parent class.

Answer

A custom exception class must directly extend Throwable.

Answer

A custom exception cannot have constructors that call super.

Question 13

A developer is debugging a Java application that throws a NullPointerException. Which two actions help identify the source of the exception? (Choose two.)

Accepted Answer

Use a debugger to step through code. Option B is correct because a debugger lets you set breakpoints and step through the code line by line, inspecting variable values and the call stack at the exact moment the NullPointerException is thrown, which pinpoints the null reference. Option C is correct because the stack trace printed when a NullPointerException is thrown shows the exact class, method, file, and line number where the null dereference occurred, immediately identifying the source. Option A is not ideal because println statements only show whatever you explicitly print and do not reveal the exception's origin or call path. Option D is wrong because the -g flag only adds debugging symbols (line numbers, local variable info) to the compiled class files; it does not itself identify where the exception came from. Option E is insufficient because catching the exception and printing only its message typically yields just 'null' without the stack trace, so the source location remains unknown.

Answer

Use System.out.println statements

Answer

Recompile with -g flag

Answer

Catch the exception and print its message

Question 14

Which TWO keywords are used to control access to class members? (Choose two.)

Accepted Answer

private. The question asks for keywords that control access to class members, i.e., access modifiers. Option A, private, is correct because it restricts a member's visibility to the declaring class only, preventing access from subclasses or other classes. Option C, public, is correct because it grants unrestricted access to a member from any other class in any package. The other options do not control access: static (B) controls whether a member belongs to the class rather than instances, abstract (D) declares that a method has no implementation or that a class cannot be instantiated, and final (E) prevents reassignment, overriding, or inheritance.

Answer

static

Answer

abstract

Answer

final

Question 15

Which TWO of the following operations on String objects result in a new String object?

Accepted Answer

"Hello".replace('l', 'p'). Option D, "Hello".replace('l', 'p'), is correct because String is immutable and replace() returns a brand-new String ("Heppo") rather than modifying the original instance. Option E, "Hello".concat(" World"), is also correct because concat() returns a new String ("Hello World") formed by appending the argument to the original, again leaving the original unchanged. Option A, "Hello".toString(), is not correct because toString() on a String simply returns this, the same existing String reference, not a new object. Option B, "Hello".length(), is not correct because it returns an int primitive (5), not a String object. Option C, "Hello".charAt(0), is not correct because it returns a char primitive ('H'), not a String object.

Answer

"Hello".toString()

Answer

"Hello".length()

Answer

"Hello".charAt(0)

Question 16

Which TWO of the following development tools are specifically designed to analyze module dependencies or create custom runtime images?

Accepted Answer

jdeps. jdeps (A) is correct because it is the Java Dependency Analysis Tool that inspects class files and JARs to report package-level and module-level dependencies, including identifying required modules and internal APIs. jlink (B) is correct because it is the Java Linker tool that assembles a custom runtime image from a set of modules, using the module graph to include only the needed JDK modules. The other options do not fit: jar (C) packages class files and resources into an archive but does not analyze module dependencies or build runtime images; javadoc (D) generates API documentation from source comments; and javac (E) compiles Java source code into bytecode.

Answer

jar

Answer

javadoc

Answer

javac

Question 17

Which TWO are valid ways to handle a checked exception in a method?

Accepted Answer

Catch the exception within the method. Option A is correct because wrapping the risky code in a try block and catching the checked exception with a matching catch clause handles it locally, satisfying the compiler's requirement that checked exceptions be dealt with. Option C is correct because adding the checked exception type to the method's throws clause propagates responsibility to the caller, which is the other standard way to satisfy the compiler. Option B is wrong because silently ignoring a checked exception does not compile; the compiler requires either a catch or a throws declaration. Option D is wrong because assert is for verifying internal invariants and cannot suppress or handle a checked exception. Option E is wrong because throwing a new RuntimeException does not by itself handle the original checked exception; the checked exception must still be caught or declared before it can be wrapped and rethrown.

Answer

Ignore the exception by doing nothing

Answer

Use assert to suppress the exception

Answer

Convert it to a runtime exception by throwing a new RuntimeException

Question 18

Which TWO are benefits of using try-with-resources?

Accepted Answer

It ensures resources are closed even if an exception occurs. Option A is correct because try-with-resources guarantees that each declared resource's close() method is invoked when the try block exits, whether normally or via an exception, which is its core purpose. Option D is correct because the Java Language Specification requires resources to be closed in the reverse order of their declaration, mirroring how nested try-finally blocks would unwind. Option B is not a benefit because finally blocks are still needed for non-resource cleanup logic, and try-with-resources only replaces the resource-closing finally pattern. Option C is wrong because resources are closed regardless of whether an exception occurs. Option E is wrong because resources need only implement AutoCloseable (Closeable is a subinterface), so requiring Closeable is not accurate.

Answer

It eliminates the need for finally block entirely

Answer

Resources are closed automatically only if no exception occurs

Answer

It requires that resources implement the Closeable interface

Question 19

Which TWO of the following are best practices for exception handling in Java?

Accepted Answer

Catch specific exceptions rather than generic Exception or Throwable.. Option A is correct because catching specific exception types (e.g., IOException, SQLException) rather than generic Exception or Throwable lets the code handle each failure appropriately and avoids accidentally swallowing unrelated runtime errors, which is a widely recognized Java best practice. Option C is correct because try-with-resources automatically invokes close() on any resource implementing AutoCloseable (or its subinterface Closeable), guaranteeing deterministic cleanup and suppressing secondary exceptions via addSuppressed(), which is the recommended pattern over manual finally blocks. Option B is wrong because blanket-catching Exception in every method hides bugs, breaks checked-exception contracts, and prevents callers from handling failures meaningfully. Option D is wrong because throwing from a finally block discards or masks any exception propagating from the try or catch block, producing confusing stack traces and is explicitly discouraged. Option E is wrong because an empty catch block silently swallows exceptions, losing diagnostic information and leaving the program in an inconsistent state.

Answer

Always catch Exception in every method to prevent crashes.

Answer

Throw an exception from a finally block to ensure cleanup failures are reported.

Answer

Ignore exceptions by leaving the catch block empty.

Question 20

Which THREE statements are true about method overloading in Java?

Accepted Answer

The return type can be different, but it is not sufficient to differentiate overloaded methods.. Option B is correct because Java allows overloaded methods to declare different return types, but the return type alone cannot distinguish two overloads — the compiler uses only the method name and parameter list (signature) for overload resolution, so two methods differing only in return type cause a compile-time error. Option D is correct because overloading is typically achieved by declaring multiple methods with the same name but different parameter lists within the same class (inherited methods can also participate, but same-class definition is valid and common). Option E is correct because the defining requirement for overloaded methods is that their parameter lists differ in number, type, or order; identical parameter lists with the same name are not overloads. Option A is incorrect because methods with the same name and same parameter types but different return types are not valid overloads and will not compile. Option C is incorrect because method overloading is resolved at compile time (static binding) based on the compile-time types of the arguments, unlike overriding which is resolved at runtime.

Answer

Two methods with the same name, same parameter types, but different return types are overloaded.

Answer

Method overloading is resolved at runtime.