1Z0-811 Java Basics and Syntax Practice Test 8 — 15 Questions

Question 1

A developer is writing a Java program that needs to store the number of items in a shopping cart. The value will never be negative and will never exceed 2 billion. Which primitive type is most appropriate for this variable?

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

Accepted Answer

int. The int primitive is a 32-bit signed integer that can represent values up to about 2.1 billion, which covers the non-negative cart count described. short overflows too early, long is unnecessarily wide for the stated maximum, and double is inappropriate for discrete counts because of floating-point representation.

Answer

double

Answer

short

Answer

long

Question 2

A junior developer is reviewing a Java source file and sees the following declaration at the top of the file:

package com.acme.util;

Which statement correctly describes the requirement for this declaration?

Accepted Answer

It must be the first statement in the file, before any import statements.. The package declaration, when used, must be the first line of a Java source file, preceding all import statements and type declarations. It applies to every class or interface defined in that file. Placing imports before the package line, or repeating the package line, produces compilation errors, making the first-statement requirement the defining rule.

Answer

It is optional and can be placed anywhere in the file as long as it is unique.

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It must be repeated in every class declared inside the same source file.

Answer

It may appear after import statements but before the first class declaration.

Question 3

A developer is writing a method that calculates the average of two integers and wants the result to include fractional values. The method signature is:

public static double average(int a, int b)

Which return statement produces the intended result?

Accepted Answer

return (a + b) / 2.0;. To obtain a fractional average, at least one operand of the division must be a floating-point value so binary numeric promotion converts the other operand. Using the double literal 2.0 forces the int sum to widen before division. Grouping the addition with parentheses is also necessary, since division has higher precedence than addition.

Answer

return a + b / 2;

Answer

return (double) (a + b / 2);

Answer

return (a + b) / 2;

Question 4

A junior developer is writing a Java class to model a bank account. The class needs a field that stores the current balance as a decimal value with high precision, and the field should be accessible only within that same class. Which declaration best meets these requirements?

Accepted Answer

private BigDecimal balance;. Storing monetary values demands a type that preserves decimal precision, and BigDecimal is designed exactly for that purpose, avoiding the rounding artifacts of double and float. Restricting the field with private enforces encapsulation so only the declaring class can touch it directly. The other combinations either lose precision, widen visibility beyond the class, or both, so they do not satisfy the scenario.

Answer

public float balance;

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private double balance;

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protected long balance;

Question 5

A developer is reviewing loop constructs in a Java utility class. Which TWO statements about Java loop behavior are correct? (Choose two.)

Accepted Answer

A while loop's condition is evaluated before each iteration, so the body may execute zero times.. The while loop checks its condition before each iteration, allowing zero executions, while the do-while loop checks after the body, guaranteeing at least one execution. These two behaviors reflect the placement of the condition relative to the loop body. The other statements misdescribe for loop flexibility, confuse break with continue, and overstate what the enhanced for loop variable can change.

Answer

The break statement inside a loop transfers control to the next iteration of that same loop.

Answer

A for loop can only be used when the exact number of iterations is known before entering the loop.

Answer

A for-each loop can modify the contents of the underlying array through its iteration variable.

Question 6

A developer writes a loop that should print the integers 0 through 4 inclusive. The code is: for (int i = 0; i < 5; i++) { System.out.print(i + " "); } Which statement accurately describes the output and the loop's behavior?

Accepted Answer

It prints 0 1 2 3 4 and terminates normally.. The three-part for header initializes i to 0, tests i < 5 before each pass, and increments i after each pass, so the body executes for 0, 1, 2, 3, and 4. Once i becomes 5 the test fails and control moves past the loop. The output is therefore the five integers 0 through 4 followed by normal completion.

Answer

It prints 1 2 3 4 5 because i is pre-incremented before the first iteration.

Answer

It fails to compile because i is declared inside the for statement.

Answer

It prints 0 1 2 3 4 5 because the condition is checked after the increment.

Question 7

A junior developer writes the following code snippet:

int x = 10;
if (x = 5) {
    System.out.println("Equal");
} else {
    System.out.println("Not Equal");
}

What happens when this code is compiled and run?

Accepted Answer

The code causes a compile-time error because the condition must be a boolean expression.. The if statement in Java requires a boolean expression. The expression x = 5 is an assignment that produces an int value, not a boolean, so the compiler rejects the code with a type mismatch error. Using the equality operator == would compare x with 5 and yield a boolean, which is the correct approach for a condition. The assignment operator cannot be used where a boolean is expected.

Answer

The code causes a runtime exception because x is assigned a new value.

Answer

The code compiles and prints "Equal".

Answer

The code compiles and prints "Not Equal".

Question 8

A developer writes a class with a static field and an instance field:

public class Counter {
    static int total = 0;
    int count = 0;
    void increment() {
        total++;
        count++;
        System.out.println(total + " " + count);
    }
}

In main, two Counter objects c1 and c2 are created. c1.increment() is called, then c2.increment(). What is printed?

Accepted Answer

1 1 followed by 2 1. A static field exists once per class and is shared by every instance, so both increment calls update the same total, producing 1 then 2. An instance field exists once per object, so c1 and c2 each modify a separate count, producing 1 on both lines. The printed output is therefore 1 1 followed by 2 1.

Answer

1 1 followed by 1 1

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1 1 followed by 2 2

Answer

2 2 followed by 2 2

Question 9

A developer needs to store whether a customer has opted in to marketing emails. The value will be either true or false, and the field will later be compared inside conditional statements. Which declaration is most appropriate for this field?

Accepted Answer

boolean optedIn;. A yes/no flag maps naturally onto the boolean primitive, which is the only Java type that accepts true and false and can be used directly in conditional expressions. Substituting String, int, or char forces an encoding convention that the compiler cannot enforce and that permits invalid states. The boolean declaration is therefore the clearest and safest choice.

Answer

int optedIn;

Answer

char optedIn;

Answer

String optedIn;

Question 10

A developer needs to store the number of active users in a web application. The value will be a whole number and will never exceed 2 billion. Which primitive data type is most appropriate for this purpose?

Accepted Answer

int. The int primitive type is designed for 32-bit signed whole numbers and covers the range up to about 2.1 billion. Since the user count will never exceed 2 billion, int provides sufficient capacity without wasting memory. Other integral types like short are too small, long is overkill, and float is inappropriate for exact counting because it represents decimal values with limited precision.

Answer

float

Answer

short

Answer

long

Question 11

A developer writes the following code: int x = 7; int y = 2; double result = x / y; System.out.println(result); What is printed, and why?

Accepted Answer

3.0, because x / y performs integer division and the int result is widened to double on assignment.. Operator evaluation happens left to right, and the type of each operand drives which division is performed. Because x and y are both int, the / operator carries out integer division, discarding the remainder and yielding 3. Only afterward is that int widened to 3.0 for storage in the double variable, so the printed value is 3.0.

Answer

3.5, because result is a double and the assignment promotes the division to floating-point.

Answer

3, because result is printed before any widening occurs.

Answer

An ArithmeticException is thrown because 7 is not evenly divisible by 2.

Question 12

A programmer writes the following code:

public class Test {
    public static void main(String[] args) {
        int i = 0;
        for (; i < 3; i++) {
            System.out.print(i + " ");
        }
    }
}

What is the output?

Accepted Answer

0 1 2. The for loop header allows the initialization section to be empty. Since i is declared and set to 0 before the loop, the loop uses that existing variable. The condition i < 3 is evaluated before each iteration, and the update i++ runs after each iteration. The values printed are 0, 1, and 2, each followed by a space. When i reaches 3, the condition fails, and the loop terminates.

Answer

0 1 2 3

Answer

Compilation fails because the initialization part of the for loop is missing.

Answer

1 2 3

Question 13

A developer is writing a Java class and needs to declare local variables that follow valid Java naming and declaration rules. Which two of the following declarations are valid and will compile without error? (Choose two.)

Accepted Answer

int maxValue = 100;. Legal Java identifiers must begin with a letter, an underscore, or a currency symbol and may continue with those characters plus digits, and they may not be keywords or the reserved literal names. The underscore-prefixed name and the camelCase name both satisfy these rules, while the digit-leading name, the hyphenated name, and the keyword name each violate a distinct restriction and fail to compile.

Answer

int 2ndPlace = 2;

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int class = 3;

Answer

int total-count = 5;

Question 14

A developer is reviewing Java code and encounters several statements involving operators. Which TWO statements about Java operators are correct? (Choose two.)

Accepted Answer

The expression 5 % 2 evaluates to 1.. Integer division truncates toward zero, so 5 / 2 yields 2. The modulo operator returns the remainder, so 5 % 2 yields 1. These two statements accurately describe Java's behavior for integer arithmetic. The other options are incorrect: floating-point division by zero yields infinity, integer division by zero throws an exception, and multiplication has higher precedence than addition, so 5 + 2 * 3 equals 11.

Answer

The expression 5 / 0 evaluates to 0.

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The expression 5 + 2 * 3 evaluates to 21.

Answer

The expression 5.0 / 0 evaluates to 0.

Question 15

A developer is reviewing a class that declares several variables at different scopes. The class has an instance field named count, and a method contains a local variable also named count. The developer needs to identify which statements about variable scope and shadowing in Java are correct. (Choose two.)

Accepted Answer

An instance field is accessible from any method of the same class regardless of declaration order.. Local variables live only inside the block where they are declared, so they vanish at the closing brace, while instance fields are members of the object and are reachable from every non-static method of the class regardless of where they appear in the source file. Shadowing a field with a same-named local variable is legal and simply hides the field until the local scope ends.

Answer

A static method can directly access an instance field of its own class without an object reference.

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A local variable with the same name as an instance field causes a compilation error.

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A variable declared inside a for loop header remains accessible after the loop terminates.