1Z0-811 Java Basics and Syntax Practice Test 3 — 15 Questions

Question 1

A developer is writing a small utility class and needs to declare a variable that will hold the number of items in a shopping cart. The value will never exceed 2 billion and no fractional values are ever needed. The developer wants the most memory-efficient primitive type that can safely store every possible value in this range. Which primitive type should be used?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

int. An int is a 32-bit signed integer with a range of roughly plus or minus 2.1 billion, so it can store any plausible cart count without overflow. It is also the standard, memory-efficient choice for whole-number counters in Java, beating long on size and double on appropriateness. Because the value is always a whole number, floating-point types are unnecessary.

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long

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double

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short

Question 2

A developer writes a class that models a bank account. The class stores the balance in a field named balance of type double. The developer wants a local variable inside a method to hold a temporary copy of the balance, and wants the code to compile without any explicit cast. Which declaration correctly assigns the instance field to a local variable of a compatible primitive type?

Accepted Answer

double temp = this.balance;. When the source and destination types are both double, the assignment is a widening-compatible identity conversion that the compiler accepts without a cast. Widening conversions such as int to double happen implicitly, but narrowing conversions such as double to int, float, or long require an explicit cast. Copying the field into another double local variable is therefore the only listed declaration that compiles cleanly and preserves the value.

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float temp = this.balance;

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int temp = this.balance;

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long temp = this.balance;

Question 3

A developer writes the following code: int x = 5; System.out.println(x++); What is the output?

Accepted Answer

5. The expression `x++` is a post-increment operator, which returns the current value of `x` (5) before incrementing it. Therefore, `System.out.println(x++)` prints 5, and then `x` becomes 6. Option B is correct because the output is the original value of `x`.

Answer

Compilation error

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6

Answer

Runtime exception

Question 4

A team decides to use a single Java source file for a small application. Which statement is true about the file structure?

Accepted Answer

It can contain exactly one public class with the same name as the file.. In Java, when a source file contains a public class, the file name must exactly match the public class name, including case sensitivity. This is a fundamental rule enforced by the Java compiler to ensure proper class loading and package structure. The file can have at most one public top-level class, and that class name determines the file name.

Answer

It must have a main method to compile.

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It can contain multiple public classes.

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The public class name can differ from the file name.

Question 5

Given the code: String s1 = "Java"; String s2 = new String("Java"); if (s1 == s2) { System.out.print("Equal"); } else { System.out.print("Not Equal"); } What is the output?

Accepted Answer

Not Equal. The == operator compares object references, not the actual string content. s1 is a string literal stored in the string pool, while s2 is a new String object created on the heap, so they refer to different memory locations, making the comparison false and printing 'Not Equal'.

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Runtime error

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Compilation error

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Equal

Question 6

Which primitive data type should be used to store a single character?

Accepted Answer

char. The `char` primitive data type in Java is specifically designed to store a single 16-bit Unicode character, ranging from '\u0000' (0) to '\uffff' (65,535). It can represent any character in the Unicode standard, including letters, digits, and symbols, making it the appropriate choice for a single character value.

Answer

int

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byte

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String

Question 7

A method is declared as: public static void main(String[] args) { }. Which statement is true?

Accepted Answer

The method can be called without creating an instance of the class.. The `static` modifier in the method signature means the method belongs to the class itself, not to any instance. Therefore, it can be invoked using the class name (e.g., `ClassName.main(args)`) without creating an object of the class. This is a fundamental characteristic of static methods in Java.

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The method can be overridden in a subclass.

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The method can return an int.

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The method can be private.

Question 8

What is the value of the expression (10 > 5) && (3 < 2)?

Accepted Answer

false. The expression (10 > 5) evaluates to true, and (3 < 2) evaluates to false. The logical AND operator (&&) returns true only if both operands are true. Since one operand is false, the entire expression evaluates to false. In Java, the result of a boolean expression is a boolean literal, not an integer.

Answer

1

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true

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0

Question 9

Which loop construct guarantees that the body executes at least once?

Accepted Answer

do-while loop. The do-while loop is a post-test loop, meaning the condition is evaluated after the loop body executes. This guarantees that the body runs at least once, regardless of whether the condition is initially true or false. In contrast, for, while, and enhanced for loops are pre-test loops that check the condition before entering the body, so they may execute zero times.

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enhanced for loop

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for loop

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while loop

Question 10

Given the code: int[] arr = {1,2,3}; for(int x : arr) { if(x==2) continue; System.out.print(x); } What is the output?

Accepted Answer

13. The enhanced for loop iterates over the array {1,2,3}. When x equals 2, the continue statement skips the remainder of the loop body for that iteration, so System.out.print(x) is not executed for 2. Thus, only 1 and 3 are printed, producing output '13'.

Answer

2

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Compilation error

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123

Question 11

What is the result of the expression 10 % 3?

Accepted Answer

1. The modulo operator (%) in Java returns the remainder of the division of the left operand by the right operand. Since 10 divided by 3 equals 3 with a remainder of 1, the expression 10 % 3 evaluates to 1.

Answer

3.33

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0

Answer

3

Question 12

Which TWO are valid identifiers in Java? (Choose two.)

Accepted Answer

$money. In Java, identifiers can begin with a letter, an underscore (_), or a dollar sign ($). The dollar sign is a valid starting character, so '$money' is a legal identifier. This is specified in the Java Language Specification (JLS §3.8).

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123abc

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2ndPlace

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my-var

Question 13

Which THREE are valid ways to declare and initialize an integer variable in Java? (Choose three.)

Accepted Answer

int x = 1_000;. Java allows underscores in numeric literals (introduced in Java 7) to improve readability, and `1_000` is a valid integer literal representing 1000. The compiler simply ignores the underscores during parsing.

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int x = 2.0;

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int x = 0xG;

Question 14

Which TWO keywords are used for decision-making in Java? (Choose two.)

Accepted Answer

switch. The 'if' and 'switch' statements are both decision-making constructs in Java. 'if' evaluates a boolean expression to determine which block of code to execute, while 'switch' selects a block based on the value of an expression, typically an int, String, or enum. These are the two primary keywords for branching logic.

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for

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try

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while

Question 15

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.