1Z0-811 Primitives, Strings and Operators Practice Test 4 — 15 Questions

Question 1

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 2

A developer needs to store a currency value with two decimal places. Which primitive type is most appropriate?

Accepted Answer

double. (double) is the most appropriate primitive type for storing a currency value with two decimal places because double is a 64-bit IEEE 754 floating-point type that can represent fractional values with sufficient precision for typical monetary amounts. While float (32-bit) could also store decimals, double provides higher precision (15-16 significant digits) and is the default type for decimal literals in Java, making it the standard choice for currency calculations in the exam context.

Answer

float

Answer

long

Answer

int

Question 3

Given: String s1 = "Java"; String s2 = new String("Java"); What does (s1 == s2) evaluate to?

Accepted Answer

false. S1 is a string literal which is interned, while s2 is created using the 'new' keyword, resulting in a different object in heap memory. The '==' operator compares object references, so it returns false. Option A is incorrect because 'true if interned' is misleading; s1 is interned, but the comparison is false because s2 is a separate object. Option C ('true') is wrong because references differ. Option D ('Compilation error') is incorrect; the code compiles and runs without error.

Answer

true if interned, false otherwise

Answer

true

Answer

Compilation error

Question 4

A method has parameters: int x, double y. It performs x += y; and returns x. What is the range behavior?

Accepted Answer

Result is truncated to int.. When the compound assignment operator += is used with an int and a double, the right-hand operand (double) is implicitly narrowed to int via a primitive narrowing conversion. This truncates the fractional part of the double value, and the result is stored as an int. The operation compiles without error and does not throw a runtime exception.

Answer

Compilation error: cannot apply += between int and double.

Answer

Lossy conversion causes runtime exception.

Answer

x is promoted to double, result is double.

Question 5

A developer writes: boolean b = !true && false; What is the value of b?

Accepted Answer

false. The expression `!true && false` is evaluated as `(!true) && false`, which is `false && false`. The logical AND (`&&`) operator returns `true` only if both operands are `true`; otherwise, it returns `false`. Therefore, `b` is assigned `false`. Option B is correct.

Answer

Compilation error: invalid operator.

Answer

NullPointerException

Answer

true

Question 6

A developer wants to assign the largest possible long value to a variable. Which is correct?

Accepted Answer

long x = Long.MAX_VALUE;. The correct answer is E. Long.MAX_VALUE is the standard and readable way to obtain the maximum long value. While option D (9223372036854775807L) is syntactically valid, it is not recommended because it is error-prone and does not clearly convey intent. Options A and C are incorrect: A has an unnecessary cast, and C omits the L suffix, causing a compile error. Option B exceeds the long range.

Answer

long x = (long) 9223372036854775807L;

Answer

long x = 9223372036854775808L;

Answer

long x = 9223372036854775807;

Answer

long x = 9223372036854775807L;

Answer

long x = 9223372036854775807;

Answer

long x = (long) 1e19;

Question 7

A developer writes: char c = 'A'; int i = c + 1; System.out.println(i); What is the output?

Accepted Answer

66. In Java, when a `char` is involved in arithmetic with an `int`, the `char` is promoted to its Unicode/ASCII numeric value. 'A' has the ASCII value 65, so `c + 1` becomes 66. The result is an `int`, and `System.out.println(i)` prints the integer 66.

Answer

B

Answer

Compilation error: cannot add char and int.

Answer

'A1'

Question 8

Which TWO of the following are valid Java identifiers? (Choose 2)

Accepted Answer

$value. ($value) is correct because Java allows identifiers to begin with a dollar sign ($) or underscore (_), and the rest can include letters, digits, or these special characters. The dollar sign is a valid starting character per the Java Language Specification (JLS §3.8), so $value is a legal identifier.

Answer

my#var

Answer

my-var

Answer

2ndPlace

Question 9

Which TWO statements are true about the String class in Java? (Choose 2)

Accepted Answer

Strings are immutable.. The correct answers are C and E. Option C is true because String objects in Java are immutable; once created, they cannot be changed. Option E is true because the intern() method places the string into the string pool if it is not already present, allowing reuse of string literals. Option A is false: String is immutable regardless of whether it is created with new or a literal. Option B is false: String does not implement Cloneable; it implements Serializable, Comparable, and CharSequence. Option D is false: methods like toUpperCase() return a new String object and do not modify the original.

Answer

String is mutable if created with new.

Answer

String implements the Cloneable interface.

Answer

String objects can be modified using methods like toUpperCase().

Question 10

Which THREE of the following expressions compile without error? (Choose 3)

Accepted Answer

byte b = 1 + 2;. Options A, C, D are correct. A: byte addition promoted to int, then assigned to byte requires explicit cast? Actually byte + byte = int, but assignment to byte will require explicit cast. Wait: byte b = 1+2? 1 and 2 are literals, compile-time constant, so assignment is allowed because constant expression. Actually 1 and 2 are int literals, but the result is compile-time constant 3, which fits in byte, so it's allowed. So A compiles. B: int + long = long, assigning to int requires explicit cast, so compile error. C: double d = 10; 10 is int, widening assignment to double is fine. D: boolean b = (false || true); boolean expression, fine. E: float f = 5.5; 5.5 is double by default, requires explicit cast or f suffix, so compile error. So correct: A, C, D.

Answer

int i = 5L + 10;

Answer

float f = 5.5;

Question 11

Refer to the exhibit. What is the output?

Accepted Answer

17. The expression `a * b + 2` follows Java operator precedence: multiplication has higher precedence than addition, so it evaluates as `(a * b) + 2`. Given `a = 3` and `b = 5`, `3 * 5 = 15`, then `15 + 2 = 17`. Therefore, option C is correct. Option A is wrong because the code compiles successfully (no error). Option B (25) would result from `(a + b) * 2` or similar misinterpretation. Option D (21) would result from `a * (b + 2)`. Only option C matches the correct calculation.

Answer

Compilation error

Answer

25

Answer

21

Question 12

Refer to the exhibit. What is the output?

Accepted Answer

Hello. The code prints 'Hello' because the `String` variable `str` is assigned the value `"Hello"` and then `str.concat("World")` is called. However, `String` objects are immutable in Java, so `concat()` returns a new string without modifying the original `str`. Since the result of `concat()` is not assigned back to `str`, the original `str` remains `"Hello"`, and `System.out.println(str)` outputs `Hello`.

Answer

HelloWorld

Answer

Hello World

Answer

Compilation error

Question 13

Refer to the exhibit. What is the output?

Accepted Answer

true. The expression evaluates to true. Operator precedence: ! highest, then &&, then ||. Given typical values (a=false, b=true), !a=true, then b && !a = true && true = true, then a || (b && !a) = false || true = true. Thus output is true. Option A is incorrect because the expression yields true, not false. Option C and D are incorrect as there is no exception or compilation error.

Answer

false

Answer

NullPointerException

Answer

Compilation error: invalid operator

Question 14

Given: int a = 9; int b = 2; double c = a / b; System.out.println(c); What is the output?

Accepted Answer

4.0. The expression `a / b` performs integer division because both operands are `int`. The result of `9 / 2` is `4` (the fractional part is truncated). This integer result is then implicitly widened to `double` when assigned to `c`, producing `4.0`. Therefore, the output is `4.0`.

Answer

4.5

Answer

0.0

Answer

4

Question 15

Given: String s1 = "Hello"; String s2 = "Hello"; String s3 = new String("Hello"); Which of the following is true?

Accepted Answer

s1 == s2 is true, s1 == s3 is false. String literals in Java are interned, meaning s1 and s2 both reference the same object from the string pool, so s1 == s2 is true. However, s3 is created using the new keyword, which forces the creation of a new String object on the heap, so s1 == s3 is false because == compares object references, not content.

Answer

s1 == s2 is false, s1 == s3 is true

Answer

s1 == s2 is true, s1 == s3 is true

Answer

s1 == s2 is false, s1 == s3 is false