1Z0-811 Practice Test 10 — 10 Questions

Question 1

A developer needs to search an unsorted array of 100,000 customer IDs (int) for a specific ID. Which approach is most efficient for a single search?

Accepted Answer

Iterate through the array and compare each element. A linear search (iterating through the array and comparing each element) is the most efficient approach for a single search on an unsorted array. It has O(n) time complexity and requires no preprocessing, which is optimal when you only need to find one element once.

Answer

Use Arrays.binarySearch() directly on the unsorted array

Answer

First sort the array using Arrays.sort(), then use binary search

Answer

Convert the array to a HashSet and then search

Question 2

Given methods: void print(Integer i) { System.out.println("Integer"); } void print(int i) { System.out.println("int"); } What is output of print(10);?

Accepted Answer

"int". When calling print(10) with an integer literal, Java's method overloading resolution prefers the primitive int version over the Integer wrapper type because the literal 10 is a primitive int. The compiler selects the most specific matching method without requiring autoboxing, so the void print(int i) method is invoked, printing "int".

Answer

Compilation error

Answer

"Integer"

Answer

Runtime error

Question 3

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.

Answer

The class is abstract.

Answer

The class has a static initializer that fails.

Question 4

A programmer wants to iterate over a list of strings and print each that starts with 'A'. Which loop construct is best suited?

Accepted Answer

Enhanced for loop. The enhanced for loop (for-each) is best suited because it provides a clean, concise syntax for iterating over a collection like a List<String> without needing an explicit index or iterator. It directly yields each element, allowing a simple if-statement to check if the string starts with 'A' and print it, making the code more readable and less error-prone.

Answer

Do-while loop

Answer

Traditional for loop with index

Answer

While loop with iterator

Question 5

Given boolean a = true, b = false, c = true; What is the result of (a || b) && (b || c)?

Accepted Answer

true. The expression (a || b) && (b || c) evaluates as follows: a is true, so (a || b) is true; b is false and c is true, so (b || c) is true; true && true yields true. Short-circuit evaluation does not prevent the overall evaluation because the left operand of && is true, so the right side must be evaluated. The result is therefore true.

Answer

Short-circuit evaluation prevents evaluation

Answer

Compilation error

Answer

false

Question 6

What is the output if an ArithmeticException occurs in the try block and there is a finally block?

Accepted Answer

The finally block executes, then the method throws the exception.. In Java, the `finally` block always executes after the `try` block, regardless of whether an exception occurs. If an `ArithmeticException` is thrown in the `try` block, the `finally` block runs first, and then the exception propagates up the call stack to be handled by an appropriate exception handler or the default handler.

Answer

The exception is caught and handled by the finally block.

Answer

The finally block does not execute if an exception occurs.

Answer

The method exits immediately without executing finally.

Question 7

What is the output of the following? int x = Integer.MAX_VALUE; x++; System.out.println(x);

Accepted Answer

-2147483648. When x is Integer.MAX_VALUE (2147483647) and incremented, integer overflow occurs because Java int uses 32-bit two's complement representation. The value wraps around to the minimum int value, which is -2147483648, making D correct.

Answer

2147483647

Answer

0

Answer

Exception

Question 8

A parent class has a static method display() and an instance method show(). A child class attempts to override both. What is the outcome?

Accepted Answer

Only show() can be overridden. In Java, static methods belong to the class, not instances, so they cannot be overridden—they can only be hidden. Instance methods, however, can be overridden to provide polymorphic behavior. Therefore, only the instance method show() can be overridden; display() is hidden, not overridden.

Answer

Both will be overridden

Answer

Only display() can be overridden

Answer

Neither can be overridden

Question 9

Given: int[] arr = {10,20,30}; System.out.println(arr[3]); What is the result?

Accepted Answer

ArrayIndexOutOfBoundsException. Arrays in Java are zero-indexed, so a valid index for an array of length 3 is 0, 1, or 2. Accessing index 3 is out of bounds, causing an ArrayIndexOutOfBoundsException at runtime.

Answer

30

Answer

0

Answer

NullPointerException

Question 10

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.